EPORT ON THE PREVENTION OF MALARIA IN MAURITIUS BV RONALD ROSS IXTMl,, F.R.C.S., D.Sc, LL.D., F.R.S., C.V> Nobd Laureaie P)t'sident Honoraire de la^Sodet^ Midicale dcflic Mavr,.^.: Corr. Eir., Acadimid da Medecinc Corr. Ester 0, Accademia di Medicina di Torino A^soc. Eel., College of Physicians of Philadelphia Officier de I Ordre de Leopold II Major, Indian Medical Service, Retired Professor of Tropical Medicine, University of Liverpool and Liverpool School ol' Tropical Medicine PRINTED BY WATERLOW AND SONS LIMITED, LONDON WALL, LOiXDON 1903, THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID REPORT ox THE PREVENTION OE MALARIA IN MAURrriES REPORT ON THE PREVENTION OF MALARIA IN MAURITIUS BY RONALD ROSS n.l'.H., F.R.C.S., D.Sc, LL.I)., F.K.S., C.B. N'o/h-l Laitreidle Presidnit Hoiiorairc dc la Socit'/J Medicalc dr I'llc Maiir/,;' Corr. E/r., Acadcmie de Mddcciiic Corr. Eslcro, Accadeiiiia di Medidna di Torino Assoc. FcL, College of Physicians of Philadclpliia Offlcicr de POrdre de Leopold II Major, Indian Medical Service, Rclircd Professor of Tropical Medicine, University of Liverpool and liverpool School of I'ropical Medicine PRINTED BY I'Z '.:. To His Excellexcv Sir cavendish BOYLE, K.C.M.G. GuvERTvOR OF Mauritius Dated, the 15th June, 190S University of Liverpool Your Excellency, In a letter No. 16 148 of the 9th May, 1907, the Ri.^-ht Honourable the Earl of Elgin, His Majesty's Secretary of State for the Colonies, informed me that your Excellency desired me to visit Mauritius in order to report on measures for the prevention of malaria there. With the consent of the University of Liverpool and of the Liverpool School of Tropical Medicine, I was able to accept the duties, and the honour, involved in this mission. In sub- sequent letters the Secretary of State adopted the suggestions that I should visit Mauritius at the commencement of the next malaria season, and that I should remain there at least three months in order to collect the information required for my report. In accordance with this decision, I left England on the 23rd October, 1907. Arriving in Mauritius on the 20th November, I was able to complete my studies by the 25th Eebruary, 190S, on which date I was permitted to return to England, where I arrived on the 28th March. I have now the honour to present for your Excellency's consideration my Report on the Preven- tion of Malaria in Mauritius. VI 2. I trust that I may be pcrmittctl, before proce(;dini^- to in\ subject, to refer to several points connected with niy \isit. On hearing- of my mission. SurL,^eon-General Sir Altretl Keogh, K.C.J)., Director-General of the Army Medical Service, was kind enough to appoint Major C E. P. P'^owler, Royal Army Medical Corps, to assist me in the work, especially as it affected His Majesty's troops in Mauritius. Major Fowler arrived in the Colony before me, but left with nie ; and I should like to add that I have received fr(jm him the greatest possiljle help in connection with my study of malaria, not only among the military, but als(j among the civil population. 3. During the visit it was necessar)' for me to carry out inspections of numerous localities in the Island. I was able to spentl ten days at Port Louis, and to examine, sometimes frequently, the i)riiicipal towns and \illages, and many of the sugar estates. I am \ery greatly indebted to the Mon. Dr. Lorans, Director of the Medical and Health Department, for the excelltMit arrangements which he made for the performance of these duties, and, not less, for the benefits of his advice; and ol the intormation which he collected for me. 1 owe m\- sincere thanks, lor accompanying and assistiuL; me on man\- of these inspections, to Dr. lulwards, C.M.Ci., Chairman ol the 'i'own Poard of Commissioners of Cure[)ipe ; to the Hon. Dr. Laurent, MaN'or of Port Louis ; to the Hon. .Sir William Newton, K.C., Chairman of the linard of (Juatre Ijornes ; to the Hon. Mv. 'i'rotter. Chairman of the Board of Rose llill and iJeau Passin ; to the Hon. Mr. Leclezio, ?**! ember of the Council of (^jo\crnment for ]\L)ka : to the Hon. Mv. Dumat, MembtM- for Saxanne ; to the Hon. Mv. (iebert, Member for (irand Port; to the Hon. Mr. I )uclos, Member for l^dacq ; to the Hon. Mr. Souchon, Member for Rixiere du Rempart ; to the Hon. vu Mr. Sauzier, K.C., Member for Pamplemousses ; to the Hon. Mr. Antelme, Member for Black River ; and to the Sanitary Wardens of the Districts. 4. It was necessary also to obtain for the purpose ot my report much statistical and other informati(Mi ; and I am nuich indebted, for the promptness and regularity with which this was collected, to the Hon. Sir Graham Bower, K.C.M.G., Colonial Secretary; to Dr. Lorans ; to the Hon. Mr. Trotter, Protector of Immignrnts; to the Hon. Mr. Le Juge de Segrais, Director of Public Works and Surveys; to Mr. P. Koenig, Director of Forests and Gardens. I am particularly grateful to Dr. Bolton, Medical Officer and Inspector of Immigrants, for the copious information and the most useful advice which he gave me regarding malaria on the Estates ; to Dr. Castel, Dr. Keisler.'^Dr. Masson. Dr. Milne, of the Health Department, for their laborious computations of the spleen-rates m Schools and Villages; and to Dr. Bour, Dr. Chauvin, Dr. Clarenc, Dr. Guerin, Dr. Harel, Dr. Leclezio, Dr. Lesur, Dr. Menage, Dr. de la Roche, Dr. Senneville, Dr. Tennant, Dr. Ulcoq, Dr. Vinson, for their similar studies on the F. states. I am much obliged also to Dr. Clarenc and Dr. Lesur for valuable literature regarding the original outbreak of malaria in Mauritius, in 1S65 67 ; to Dr. de Chazal for his excellent report on the recent outbreak at Phoenix ; to Dr. Momple for information regard- ing Sanitary Legislation ; to Mr. Naz of the Health Depart- ment ; to Mr. A. Walter <)( the Observatory, for information on certain meteorological points ; and to Drs. Cretni, Gromett, Lafont, Lesur, Menage, Rouget, and all the members of the medical profession whom I met in Mauritius, for help rendered in various ways. 5. Early in the course of my studies, your Excellency was pleased to place at my disposal the services of Vlll Mr. cri'^ninierez cic Charmoy, Curator of the ^luscuin, whose car]\- and achnira])]e work on the Ciiliciche of Mauritius and on malaria there, carried out j)artl\' in conjunction with Mr. I )arut\' de Grandpre, is well known to students of these subjects. The assistance of Mr. d'h.mmerez, and, 1 may add, the \-oluntar\ help rcnderc;d 1)\ Mr. I)arut\ , pro\ cd lo he inxaluable to us; without their aid we should not have had time to complete the essential laborator\" work which it was our dut\ to attend to. Major I'owler and I would like it to be considered that, as regards the examination ot cases ot malaria and ot mosquitoes, th(;s(! gentlemen acted in scientihc collaboration with us. 6. The whole subject of the prexention of malaria in Mauritius was frequently discussed with many members of the medical profession in the Island ; and on the 24th [anuary, owinLi" to the kindness of Drs. Clarenc and Chevreau. I'resident and .Secretary ol the Societe Medicale, 1 had an opportunit\' of considering' the matter with that bod\'. I think it may be accepted that there will be a \ery general consensus among the professi(jn as regards the principal measures to be undertaken. 7. The nature ol these measures became exident tairl\' early in the period of mv mission — though indeed the\ had Ijeen recognised long prcviouslv. It had therefore; appeared to me to l)e highly desirable that, before the submission ol this rej)ort, and during my stay in Mauritius, some attempt should be made to commence the necessary organisation on a preliminary scale by training a sniall staff of men to the work. Your Excellency responded at once to this suggestion b\" placing the sum of Rs.6.000 at the disposal of the Medical and Health Department for ihc purpose. ( )ut of this fund ten " moustiquiers '" and ten working gangs of three men each were enlisted, were instructed in the duties described in the Report, and, even before I left, had done a considerable amouiU of work. Moreover, the Chairman of Ouatre Bornes, Curepipe, and Beau Bassin, and the municipahty and District of Port Louis commenced simihir measures ; the managers of many of the Sugar Estates asked for the services of the moustiquiers ; a small fund, generously subscribed to by the Hon. Mr. Souchon, Messrs. Ireland and Fraser, and the Bank of Mauritius, was started t(j supply working gangs to certain villaoes; and the elected members of Council for the Districts took similar action. On the 29th January I had the honour to deliver a public lecture on the subject before your Excellency at Curepipe. and, on the 8th February, a similar one before the Mayor and Councillors of Port Louis. Before I left, your Plxcellency appointed Mr. d'Emmerez de Charmoy to superintend the malaria work under the Medical and Health Department, as a temporary measure pending the receipt of this report. S. Among larger measures for the suppression of malaria recently undertaken in Mauritius. I should like to mention the drainage of the marshes at Phtt^nix by your Government and the handsome assistance given by the hnperial Govern- ment through the military authorities. 9. We are also much indebted to Major General Creagh, C.B.. Commanding the Troops ; to Colonel Peterkin. Major Wilson, Lieut. Buchanan, and Lieut. Wallace of the Royal Army Medical Corps ; to numerous Officers of the Garrison ; and to a large number of private gentlemen in Mauritius ; all of whom have helped us in many ways. 10. Lastl)-, Sir, our warmest thanks are due to yourself, not only for much personal kindness, but for the great assistance which \ou have always been pleased to give us. I can only hope that the marked and intelligent interest in the subject of malaria shown by everyone in Mauritius will be ultimately rewarded by a large reduction in the disease, and an increase of health and prosperity throughout the Colony. PREFACE. The pre\'ention of nicikirlci must always make demands on the pubhc purse and, in the case of estates and phuitations, on the private purse also. Hence all recommendations for dealing with the disease should be supported by thoroughly reasoned arguments in their favour ; and such reasoning must obviously be based upon our modern knowledge ot the subject. I have therefore thought it advisable to commence this Report with a chapter written in non-technical language on malaria in general — a course which is demanded the more because there is ncj good text-book on the subject. I fear that there is considerable evidence of haste in the work. The necessity for com[)leting it as early as possible, in order to permit of preparations being made tor the commencement of the proposed campaign at the beginning of the next malaria season, has been exigent. The labour of tabulating and anahsing the returns of the spleen-census (probably the largest one ever made), and of considering the historical statistics of malaria in Mauritius, has occupied much of the axailable time ; and I have been obli'>-ed to xn defer to anotlu-r oi^porluiiilN' the cxciinin.-iiion of maiu' ([ucstions of theoretical interest arisinc^" trom these fioures. In makini^' my rcconimendati(jns I ha\"e endea\-()ured to select nn\v those preventi\'e measures which. I think, are certainK' feasihle and which, when combined in the wa\' indicated, are likely to f;ive the best and most dehnite results for the least expenditure ; and I have considered very carcfulK' the special organisation re([uired for the prevention ot malaria in the tro[)ics. Summaries of the substance of the Report are contained in sections 21 and 40. Ro.NALij Ross. UnIVEKSIT\' Ol- Ll\ EKl'OUL 15/// /?n/i\ T908 CONTENTS. PART I.— MALARIA IN GENERAL Section i. History 2. Compendium of Facts regarding Malarial Fever . The parasites and the fever— the mode of infection — facts about mosquitoes — personal jirevention — public prevention 3. The Duration of the Infection . 4. The Parasites between the Relapses . 5. Causes of the Relapses . . . . ■ . 6. The Proper Duration of Treatment 7. The Proofs of the Mosquito Theorem . 8. Do OTHER Insects carry Malaria? 9. Is Malaria due to the Soil?. 10. What do we mean iiy the Amount of Malaria in A Locality? 11. Factors which influence the Infection Rate. 12 Conditions which change the number of Infected People in a Locality ..... 13. The Number, Len(;th of Life, and Diffusion o Anophelines in a Locality .... rAGK I 15 18 19 21 22 23 24 29 30 33 37 PART II.-MALARIA IN MAURITIUS Sfxtion 14. Short Description of Mauritius . 15. The Outp.reak of Malaria in Mauritius 16. Explanation of Outbreaks of Malaria 17. Further History of Malaria in Mauritius . 18. Statistics of Malaria in Mauritius since the Outbreak ....... The general death-rates of certain non- malarious islands — the "eneral death-rates of Mauritius — monthly variation in the Jlt-aths — tile declared fever mortality — cases of malaria admitted into hospitals and asylums — cases of malaria attending the hospitals and dispensaries 41 43 49 52 56 XIV I'ART II. — io)i/iinted. PAGE Skctiox 19. Thk Mkasukkmkm' of Malaria i\ Mauritius . 65 Recent statistics — direct methods for nieasurini; tlie animiiU nf malaria in a locality — the endemic index — does kala-azar exist in Mauritius ? 20. The Spleen-rates of Children in Mauritius, and other details ....... 69 Total spleen-rate — total probable endemic index — some small sources of error — average spleen— local distribution — llie ' •• imported s]ileen-rate — the effect of altitude — relation lielween the spleen-rates and general death-rales^the i^arasites and tlie U\ ers in ?^Iauritius • 21. SUMMARY OF FACTS REGARDING THE AMOUNT OF MALARIA IN MAURITIUS . IX l'.\R'r III.— PREVENTION OF A[.\L.\KL\ IX M.M'RniUS Section 22. Brief History of the Prevention of Malaria . . 76 23. The Prevention of Malaria in Ismailia, the Federated Malay Sta'tes, Hono Koxc, thi'. Panama Canal Zone, etc. ..... So 24. Pki:Li.Mi\ARY considerations recardino Prevention 91 r'onn of government — the first ])reliminary to success — necessity for re]ieated measurements of malaria — limits of expenditure on anti-malaria work — all measures against malaria must be Continued indetinitely — some legislation and tliscipline necessary- -special organisation advisalile — a tirni continuous govermnent policy necessary 25. The various Preventive Measures considered . 95 Isolation — punkas and segregation — case reduction — (juinine- ]irophylaxis — Anopheline reduction — public instruction 26. The various Preventive Measures compared . loi 27. The general Preventive Measures selected for Mauritius . . . . . . .104 28. Tht: 1'eriodical Stli;i:n-Census . . . .104 29. Tkkatment OF Childri'.x IN Schools and ON Estates 106 30. Other Quinjne Distribution . . . . . loS For towns, villages, and isolated liouses — for tlie estates — prejiaration and despatch of quinine iirejiaralions — remarks 31. House Protection . . . . . . .112 32. Mosquito Reduction . . . . . .112 2,T,. ])f:tails of Minor Works . . . . • I'o Nature of works — organisation of workmen in gangs — total number of gangs required for Mauritius — number of workmen recjuired for lowns, villages, and populous areas — minor works on estates — the ni(iustii|uieis — the malaria authoril\- — todls and implements XV '■/ PAGE Sfxtion 34. Details of Major Works . . . .119 35. Legislation ani) Administration . . ., .120 Amendments of laws — existing sanitary staff — plague service — standpipes — drains and gutters — water channels — marshes on private property 36. Notes on Prevention in the Towns . . ' " . 123 Port Louis — Curepipe — trees in towns 37. The Annual Malaria Report. .'; . " _' . -1-7 3S. Miscellaneous Suggestions . . . . .127 Intercepting drains— rubble drains — stoning irrigation pits and water channels — rough canalisation— holes in rocks and trees — mosquito plants — the introduction of J/, rossii 39. The General Plan of Campaign . . . -130 40. SUMMARY OF PRINCIPAL RECOM- MENDATIONS, AND APPROXIMATE COST . . .131 ADDENDA 1. The Mosquitoes of Mauritius . ' .- • •■ . 133 2. The Clairfond outbreak with Report v,\ Dr. de Chazal and map 134 3. The question of the River Reserves . . .140 4. Statistical error ....... 144 REFERENCES .... ... 146 ANNEXURES 1. Letters from Dr. Uolton and Dr. Malcolm Watson i47 2. Correspondence regarding water-channels . -149 3. Draft Legislation 151 4. Rough estimates of workmen and works, prepared — (A) By the Pvledical Department, . . • -153 (B) By the Immigration Department, .... 155 (C) By the Pubhc Works and Surveys Dej artment. . 164 XVI TAT'.I.ES I. I'lii'iM.A riox, ukaths, an'u hkci.arf.d rnvKR deaths . 172 II. I )lt lAKlD llAl.k UKAIHS IN THK SKVF.RAL TMSTKICTS. I 74 III, Cases ok malaria attkndixc hospitals axu DISPENSARIES ........ 174^ 1\'. Si'i !■ i:n-rat1';s of tun iiri;n — A. (Ml suL^ar estates . . . . . -175 15. ill schools . . . . . . . .178 C. ill various localities ...... 181 n. summar}- . . . . . . . 1S3 E. according to altitude . . . . . .184 1'". compared with death-rates in districts . . . 1S5 1M..\X OF (;i.AIKFOXl) M.\KSHES 186 PHOTOGRAPHS 1-4. A'n \\s ......... 189 5-10. Houses . . . . . . . . .191 n -17. Breedinc i>laces of Anophei.ines . . . 194 18 20. HrEFDIXO places of C'lLICINES .... I98 2 1. Child wiih crkatln enlar(;fd spleen. . . 200 22. Xef for measurinc; ouiput of Anophflines . 200 23-25. RoUOH training of SIKEAMS. .... 201 REPORT ON THE PREVENTION OF MALARIA IN MAURITIUS. PART I.— MALARIA IN GENERAL. I. HISTORY. — Malarial P'ever was well known to the A/iiieiits, who certainly reco^niised three main facts connected with it. They observed that the disease occurs in several different forms, the qiiartaii, the tertian^ and the continued form. The}- knew that it tends to be most prevalent in the vicinit\- of marshes ; and that it may be reduced by drainage. The Middle Ai^es added little to our knowledge of the subject. In 1640, however, the specific remedy for the disease, the so-called Cinchona or Peruvian Bark, began to be known in Europe ; and in 1820 Pelletier and Caventou extracted from this substance its essential principle, quinine. The extensi\e use of the drug made by ph}'sicians ultimate!)^ showed that it does not cure all fevers, but only those which possess the so-called intermittent tendency — that is, the tendenc}' to a succession of attacks at regular periods. This fact enabled them to separate these fevers clearl\- from the others, known as the Continued P'evers. It is true that the Intermittent P'evers may become continued at times ; but, as Torti showed in 17 12, this is merel}' due to the overlapping of the successi\e attacks. In 1691, Morton, and in 1716, Lancisi, strongly emphasised the ancient opinion that the Intermittent P'evers are caused in some way b\' noxious cfflu\ia from marshes. Accepted widely throughout the world, this h\-pothesis ultimately gave another name to the Intermittent Fevers, namel}-, that o{ Malarial Fever — which connotes that the disease is due to bad air. It should, however, be clearly recognised at this point that the last conception was entirely an hypothesis — a conjecture. It was absolutely true that Intermittent Fever is caused in some way by sonicthiiig which emanates from marshes ; but it was never proved, either b}- induction or by experiment, that this "something" is the air of the marsh. The conception regarding the " bad air " was therefore nothing but an attempt to explain with plausibility the great fact that the Intermittent Fevers are, for some reason, certainh' connected \\\\\\ marshes. Nevertheless, it shortl)- began to be accepted everywhere as a dogma. Later still, w hen these fevers were found to occur in certain places where there were no marshes, the dogma was expanded into the h\-[)Othesis of the telluric iiiiasiiia. According to this the malarial poison exists, not onh' in marshes, but an}-where in certain soils, especially where there is much decaying vegetation. It was thought that if such soils be disturbed in an\' way the poison will rush out into the air and infect the neighbourhood. Here again there was no experimental evidence, and the whole speculation rested merel\- on some loose inductions. About the middle of last centur\-. howe\er, the science of experi- mental [jatholog}- came into being. We no longer accepted coincidences and conjectures as proofs, but studied disease b\- strict experimental methods. Gerhardt produced malarial fe\er in men by inoculating them with a small quantity of blood taken from patients — thus proving that the disease is caused b\- an organism existing in the blood ; and in i SSo Laxeran discovered this organism itself. It prcjved to be a minute animal parasite of vcr\- low order, and visible onl\' b\- the microscope, which lives in the blood in enormous nunibers. Some \ears later Golgi and others showed that these minute bodies j)roliferate indefinitel}- in human blood b\- the simultaneous production of spores ; that the successive attacks of fever in the patient commence at the moment when the spores are set free from the jjarent organisms ; and that there are at least three varieties of the parasites, all of which can be distinguished by the microscope — namel}', one which produces spores every three da\-s and causes (juartan fever, one which produces spores every other da\' and causes tertian fever, and cMie (at least) which causes less distinct, but often more dangerous, attacks. About the same time Danielewsky showed that closeh' allied parasites occur in birds (the\- have now been found also in monkeys, bats, and squirrels) ; and discovered many 3 more distantly related organisms in numerous animals. Laveran, Marchiafava, Celli, Bignami, Canalis, and man}- others made a close stud}' of infected persons. Romanowsk}- and Ziemann developed a method of staining the parasites which serves to demonstrate them \\'ith certainty ; and Theobald Sn^iith discovered a nearly related [parasite of cattle which is carried from ox to ox by a species of tick — as he proved b\- direct experiment. This brilliant series of researches, which were soon confirmed and amplified b}- numbers of observers in many parts of the world, gave us most exact and detailed information regarding the processes which cause the disease in man. But a great problem still remained — to ascertain the route by which the parasites enter the human body. As soon as these had been discovered, many workers, remembering the connection between Malarial Fever and marshes, sought for them in such localities, thinking that they probably bred there and infected man by inhalation ; and others, especially Celli, Agenore, and Calandruccio, attempted to cause infection b}- the air or water taken from malarious localities — but all without success. In the meantime another, but \er\' old, h\-[)othesis had been revived. Even some centuries ago it was stated in certain religious books of Ceylon that mosquitoes can produce fever ; and the same idea now occurred to several eminent men of science. It must be remarked, however, that the views of these authors were still only speculations, which they themselves did not verif)- by serious experiments ^although such might easil}- ha\c been attempted), and that their h\'pothcses were often as much wrong as right. Obvious!}- the whole problem was a very difficult one, which could be sohed onl}- by long thought and investigation. This was attempted by m}- own work, commencing in India about 1891 and not concluded until 1899. It became early apparent that the old hypothesis of an aerial miasm was not tenable, simpl}- because the disease was frequentl}- too local to be assigned to an}- widel}--diffusiblc poison. Karly in 1895, therefore, I commenced an experimental stud}' of the mosquito hypothesis. After long failures with the commoner kinds of mosquito of the genera Ciilex and Stegomyia, I succeeded at last (August, 1897J in growing the malignant parasite of man in mosquitoes of the sub-family Anophelina. Next year the life-history of the whole group of these parasites was worked out in 4 the case of one of the parasites of birds in a mos(iuito of tlie i^enus Cii/iw, and tlie wonderful and unexpected result was obtained, both on microsco[)ical evidence and b)- the actual production of the disease among the birds, that the malarial infection takes place through the proboscis of the mosquito. After an interruj^tion, I was finalh' able to demonstrate the exacth" similar life-histor\' of all the human parasites in the Anophelines costalis and fiinestus in Sierra Leone in 1899. This completed the solution, but at the end of 1898 m\- work had alread)' been \erificd by Koch, Daniels, l^ignami, Bastianelli and Grassi, the latter of whom, entirel\- b}- following m}- methods, infected healthy men in Ital}- and showed that the tertian parasites are also carried b\' Anophelines in that countr)-. These results were rapidh- confirmed and amplified b}- a host of obser\ers — b\' Daniels, Stephens and Christophers of the Malaria Commission of the Royal Society, b\- various expeditions, and by many private workers. Koch disco\ered the important fact that native children are the principal source of infection in the tropics. Ziemann, Fernside, I^uchanan and Manson produced infections b\- mosquitoes in more human beings, the last in the middle of London, b\' mosquitoes brought from Ital}-. Low and Sambon remained free from malaria in the Campagna b\- lixing in a mostiuito-proof house. Austen, Giles, Stephens and Christophers, Howard, Hlanchard and Theobald studied the mosquitoes themselves, the last producing his exhaustive monograph on the subject. The similar development of several parasites allied to those of malaria has been worked out in \arious insects. Local mosquitcx^s and their habits have been studied in many places — notabh- b}- Darut}- de Grandpre and d'Emmerez de Charmo}' in Mauritius. It should be added here that even before the discovery of the malaria parasite Manson had worked out part of the Iife-histor\- of Filaria bancrofti, the worm which causes elephantiasis and allied diseases, in a species of mosquito ; and that a little later Finla\- conjectured that yellow fe\er, the scourge of tropical America, might be carried b\- the same insects. Now, following the suggestions of mj- work on malaria, James and Low 1900) completed the life- histor}- of Filaria ba>icrofti, and showed that it also probabh" gains an entrance into the human bod}' through the mosquito's proboscis ; and Reed, Carrol, Lazear and Agramonte pro\ed (1901) by the most conclusi\e experiments that )-ellow fever is transmitted in the same 5 way. Hence we are now certain that at least three diseases of man are carried by mosquitoes ; while dengue and some other fevers may perhaps be added to the list. Bruce had long previously shown that Tsetse Fly disease is carried by the insects of that name. My studies had been undertaken solely with the object of im- proving our methods of preventing malaria ; and the history now turns to this, the most important branch of the subject. When my work commenced little was known about mosquitoes. Only about one hundred species had been distinguished ; the classification was elementary; and the little knowledge of their habits we possessed was not generalised, was buried in the works of a few entomologists, and was not familiar to sanitary science. Thus King in 1883, and Bignami in 1896 evidently thought that all mosquitoes breed in marshes; and even Manson in 1896 believed that they live only for four or five da}\s. But the long Indian researches, carried out in many parts of that empire, brought to light several generalisations which I have subsequently found to hold good in countries so far apart as Sierra Leone, Gambia, the Gold Coast, Lagos, Panama, Ismailia, Greece, and Mauritius, and which should now be men- tioned briefly, as the}' form the basis of the prevention of disease by mosquito reduction. Thus mosquitoes do not live only for a few days, but f<3r a month or more, even in captivity — feeding and la}'ing their eggs regularly during their life. The commonest mosquitoes in the tropics nearly always belong to three groups, now known as Cuhw, Sti'goi/iria, and Aiiopheliiia, which carry different parasites, have different habits, and can be generalh- distinguished by certain salient characteristics which are easil}- recognisable b}' any one — even by native villagers. All mosquitoes tend to abound most nearest to their breeding places, and can with certaint}- be reduced in numbers an\'where by appropriate and continuous measures directed against the latter, Culcx and Stegoiiiyia breed principally in artificial collections of water (in the tropics) ; but the Anophelines breed principall}- in natural collections of water. The last point was made out in Lidia and Sierra Leone from 1897 to 1899, and gives a full explanation of the long-known connection between malaria and marshes — the mosquitoes which carry malaria breed in marshes. For the same reason it is unlikely (as indeed my work had already proved) that Culex and Stegoiiiyia carry malaria — because they do not breed so much in marshes as elsewhere, for example, in pots and tubs round houses. Lastly, the fact exj)lained and justified the ancient method of reducing; malaria by drainage — that is, by mosquito reduction. At the same time this ancient method was now rendered much more simple, cheap and \-et exact by the knowledge that we ha\e to drain only tlvjse waters which breed Ano[jhelines. The impro\-ed system, and the [)recise habits of the larv;e of the insects upon which it depends, were first described by me in a series of articles i I i* during my first \ isit to Sierra Leone in 1899. I proposed, in short, to free towns of malaria b\' the simjile and radical [jrocess of clearing them of mosquitoes b\' destro}'ing the breeding places of the insects. Lnfortunateh% howexer, the extraordinar\' objection was urged that this measure would be useless, owing to the immigration of mosquitoes from without (section 13); and fir three }'ears I failed in obtaining a trial for m\- method. At last, in 1901-2, it was put into practice at ni}- visits to Sierra Leone and Ismailia, in the latter place with the most brilliant success ; and was also used with as good results in the h\^deratccl Ahdax- States b}' Dr. Malcolm Watson. hi the meantime the discox'ery that yellow fever is carried b\' S/rj^v/z/j'/d, led the Americans, imder Ciorgas, to adopt similar measiu'cs in Havana and subseciuenll}^ at Panama. In detail, the s}-stem is some- what different for the two diseases, as the habits of the carr\-ing insects are dissimilar ; but the great principle, the idea of making a general clearance of mosquitoes and diseases together is the same. In places where it is intelligent!}' ftllowed it will probabl\- reduce sickness at one sweep b\- from one-([uarter to one-half or more. Like Listerism, however, the idea has spread slowly, and the [)ractice more slowh' still. The historv of the progress made will be found in a recent [)aper 1))- me (2), and in sectitni 22. Meanwhile other methods oi pro[)hylaxis were urged by various workers. Koch and Celli elaborated prevention b\' quinine, and put it into practice in Ital}- and elsewhere ; and Celli, Manson and others advocated the protection of houses by wire-gauze ; while administrators like Sir William MacGregor ado[)ted all methods. Very successful results ha\e l)een obtained ; but the conditions in the tropics are as a rule more fa\ourable fir the radical measure of drainage. * The references will l)e found on page 146. It is impossible in this brief history to mention the names of all the workers — even of some of the most distini^uishcd — who have built up our modern knowledge of malaria ; and the details mentioned have been given only in order to convince the lay reader that that knowledge was not obtained in a day, and is not a mere speculation on the part of the medical profession. 2.^C0MPENDIUM OF FACTS REGARDING MALARIAL FEVER.— (l) The Parasites and the Fever. — Malarial Fever occurs more or less in all warm climates, especially in the summer, after rains, and near marshy ground ; and produces a quarter or more of the total sickness in the tropics. It is caused by enormous numbers of the minute parasites of the blood, called Plasmodia or Hsemamoebidai. These parasites are introduced into the blood through the proboscis of certain species of the mosquitoes called Anophelines. On being introduced, each parasite enters one of the red corpuscles of the blood, in which it lives and grows. On reaching maturity' each parasite produces a number of spores which escape from the containing corpuscle, and enter fresh corpuscles ; and this method of propagation may be continued indefinitely for years. Thus, though only a few hundreds or thousands of the parasites may have been originalh' introduced through the mosquito's proboscis, their number rapidly increases, until as many as some millions of millions of them may exist in the blood. At first, while the number of parasites is still small, the infected person may remain apparently well. When however the number is large enough, he begins to suffer from fever. The parasites tend to produce their spores all at the same time ; and it is at the moment when these spores escape that the patient's fever begins. The fever is probably caused by a little poison which escapes from the parasites with the spores. After from six to forty hours or more this poison is eliminated from the patient's system ; and his fever then leaves him temporarily. In the meantime, however, another generation of parasites may be approaching maturity, and may cause another attack of fever like the 8 first ; and so on, indefinite]}', for weeks or months. In this manner the attacks of fever follow each other at rei,ailar intervals. l^ut it often happens that before one attack has entireh' ceased another one commences ; so that the attacks o\erlap eacli other, and the fever is continued. After a time, even without treatment, the mmiber of parasites ma\' decrease, until not enoui;h of them are left to produce fever ; when the patient impro\es temporaril\-. It L;enerall}' happens, however, sooner or later, that the number of parasites increases again ; when the patient again sufiers from another series of attacks. Such relapses are frequently encouraged by fatigue, heat, chill, wetting, dissipation, and attacks of other illness. They ma}' occur at intervals for many }'ears after the patient was first infected, and after he has nioved to localities where there is no malaria. It is probable that so long as one parasite remains alive in the l)aticnt's blood, he may remain subject to such relapses. Besides fever, the parasites often produce an;emia and enlarge- ment of the spleen, especiall}' in patients who ha\e suffered from man}' relai)-es. Death is sometimes caused b\- sudden and gra\-e s}-mptoms. Chief among these are the s}-mptoms known as Blackwater Fc\cr, or Hjemoglol)inuria, which gencrall}- occurs in old and neglected infections. Death is also otten caused dui-ing the course of a malarial infec- tion by other diseases, such as pneumonia or dx'scnter}-, acting on a constitution enfeebled b\- the parasites. If the patient sur\i\es, the parasites tend to die f)ut of themsehes without treatment after a long period of illness, leaving him more or less " immune." Tin- parasites are of at least three kinds. whi(-h can easil}- be dis- tinguished in blood |jl;n-ed under the microscope. These are j^ the parasite which produces its spores ever\- three da}-s and causes quar- tan fever ; (2) the parasite which ])roduces its spores every other da}- and causes tertian fever : '3) parasites which cause the so-called malignant fever, in which dangerous complications most frequently occur. 9 Closely similar parasites are found also in monkeys, bats, squirrels and birds. As proved by centuries of experience, Cinchona bark, from which quim'ne is made, possesses the power of destroying the parasites and curing the infection. But it will not generally destroy all the parasites in the body unless it is given in sufficient doses and continued for several months. (2) TJie Mode of Infection. — Besides those forms of the malaria parasite which produce spores in the human body, there are other forms, male and female. When certain species of the mosquitoes called Anophelines happen to feed on a patient whose blood contains the parasites of malaria, these are drawn with the blood into the insect's stomach. If the sexual forms of the parasites are present these undergo certain changes in the mosquito's stomach ; the females pass through its wall ; and finally fix themselves to its outer surface — that is, between the stomach and the skin of the insect. In this position the}' grow largely in size, and after a week, in favourable circumstances, produce a number of spores. The spores find their way into the insect's salivary glands. This gland secretes the irritating fluid which the insect injects through its proboscis under the human skin when it commences to feed, and the spores can easily be found in the fluid by the microscope. Thus when a proper species of Anopheline, which has more than a week previously fed upon a patient containing the sexual forms of the parasites of malaria, next bites another person, it injects the spores together with its saliva under his skin — that is generally into his blood. These spores now cause, or may cause, infection or re-infection in this second person, as described at the beginning of this compendium. Numerous birds and men have been infected experimentally in this manner. Thus the parasites of malaria pass alternately from men to certain mosquitoes, and back from these mosquitoes to men. A very large number of parasites are known which pass in this manner from one animal to a second animal which preys on the first ; and back a^ain from the second animal to the first. to It is not known with certaint\- when and how this jirocess first commenced ; but probably all such parasites were oriL^inally free living animals, which, by the gradual evolution of ages, acquired the power of living in other animals. Thus also, it is evident that malarial fe\er is an infectious disease which is communicated from the sick to the health}- by the agency of certain mosquitoes. From the time of the ancients it has been known that malarial fever is most prevalent in the vicinity of marshes. The parasites of malaria have ne\er been found in the water or air of marshes ; nor in deca\'ing \-egetation ; nor in the soil. But the Anophelines which carr\' the parasites breed in marshes and marsh}- pools and .streams. Rising from these marshes, they enter the adjacent houses and feed on the inmates, mostl}' at night ; biting first one person and then others ; and living for weeks or months. If an infected person happens to be present in an}- of these houses, the infection is likely to be carried b}' the Anophelines from him to the other inmates, and to neighbouring houses. Thus the whole neighbourhood tends to become infected, and the localit}' is called '' malarious." In such localities, it is easy to find the parasites of malaria in the Anophelines of the proper species ; even in as many as 25 % of them. .Such Anophelines when taken from a malarious localit}- to a health}' one {e.^^. from the Campagna near Rome to London) will still infect health}' persons whom the}' ha\c been caused to bite. So also, in malarious localities, the Anophelines bite the healthy new-born children and infect many of them. Such children, if not thoroughly treated, ma}' remain infected for years ; ma}' become an;emic and [possess enlarged spleens ; and ma}' spread the infection to others. Later however, at the age of twcKe years or more, the survivors tend to become " immune.'.' In many malarious localities, almost ever}' child has been fi)und to contain the parasites of malaria, or to jkjsscss an enlarged spleen. In such a localit}' therefore, the infection is conslantl}' jxassed on from the older children, or from adults, to the new-born infants ; so that the localitx" ma\' remain malarious for \'ears or for centuries. II Similarly, a new-comer arriving in such a locality is very likely to become infected, especially if he sleeps in an infected house, even for one night. A locality is said to be malarious only when healthy persons become infected in it ; not when persons who have become infected elsewhere happen to reside in it. A locality is malarious only when it contains persons already infected with the parasite, and also sufficient numbers of the proper species or varieties of Anophelines to carry the infection to healthy persons. The chances of infection tend to be great in localities where there are already numerous infected persons, not treated with quinine ; or where there are numerous Anophelines of the proper species, not prevented from biting. Conversel)% the chances of infection tend to be less where infected persons are excluded, or properly treated with quinine ; or where the Anophelines are few in number, or are prevented from biting. (3) Facts about Mosquitoes.— Gw^Xs, which in the tropics are commonly called mosquitoes, belong to the zoological family of insects known as the Culicidffi (from the Latin ailcx, a gnat). They are distinguished from other insects by a number of characters ; and always possess only one wing on each side, and a long proboscis. Like that of other insects, their life is divided into four stages, the cgg\ the larva (or caterpillar) ; W\q pupa (or chrysalis) ; and the ////<'?i;v (or adult, winged insect). The egg is laid on water or near it, and in warm moist weather hatches out in a day or two. The larva is entirely aquatic, and always lives in water. It swims and dives by means of paddles and hairs, and feeds on various aquatic organisms. It cannot however breathe under water, but must always rise to the surface in order to obtain air. After a week or more it becomes a pupa. The pupa still remains in the water, generally floating on the surface. After two da>'s or more its skin cracks and the imago emerges. The imago remains standing for a little while on the empty floating skin of the pui)a and then flies away. Both males and females are able to suck fluids through the proboscis. As a rule the 12 male feeds only on the juices of plants ; but the female sucks the blood of men, beasts, birds and reptiles. The female returns to water ever>- few da}-s in order to la\' her eggs, of which she ma}- deposit several hundreds at a time ; and then seeks another meal. Female gnats have been ke])t alive in captivity for months. In unsuitable weather, both males and females may take refuge in damp places such as cellars, wells, outhouses and woods, where the\- may remain dormant for months until better conditions prevail. As a rule, gnats like other animals tend to remain in the localit}- where ihey were born ; but a (c\v ma}' occasionall}- stray to some distance. When a strong wind i)revails they usually take shelter ; but on warm, still nights or da}-s man\- of them may wander to a distance of half a mile or more from their breeding places. If however plenty of places exist near at hand where they can obtain food, there is no reason wh}- the}' should travel further for it. They must also remain near water to drink and to lay their eggs in. Gnats are favoured b}' warm weather ; b}- plent}- of water suitable for their larvae ; b}- abundance of food ; and by the absence of various kinds of bats, birds, fish, insects and spiders which devour them or their larv;e. During its life, a single gnat may succeed in biting man}- persons or animals, and in propagating diseases amongst them. The family of Culicid;t or Gnats is divided into many sub- families and genera, and contains some five or six hundred known species. Although all these species haxe man}- habits and structural characters in common, }et the}- all differ in small details. These have been described at length in a n-amber of special books written on the subject. In the tropics, as a broad general rule, the gnats which most concern human beings belong to the groups called Cu/cx, Sh'goii/rid and .'\nophelina. Liilex pipicns is a \er}- comnion gnat in Europe, and allied species are found almost ever}'where in the tropics. The larv;u occur principill}- ill tubs, barrels, cisterns and other vessels containing water, in stagnant ditches, garden pits, holes in rocks and trees, and so on. The}' jjossess a long breathing tube close to the tail fins, and float at the surface of the water with the end of this tube attached to the "surface film," and the heat! hanoino- downwards. 13 When disturbed, they wriggle at once to the bottom. The adult insects generally present a uniform grey appearance, with pale yellowish bars across the back of the abdomen, and plain unspotted wings. They bite almost entirely in the evening and night, and principally indoors (in the tropics). The parasite which causes elephantiasis, namel}' the Filaria baiicrofti, is carried by them in a manner very similar to that in which the Anophelines carr}- the parasites of malaria. Stegoiiiyia fasciata and S. sciitellaris are very common in the tropics, but much less so in temperate climates. The larvae breed in much the same places as those of Ciilex, but more frequently in vessels. Any old biscuit or oil tins, flower pots, broken bottles, and crockery, tubs and barrels, choked drains, roof gutters, &c., in which rain or other water has collected, is almost sure to contain them, and they frequently occur in holes in trees and in certain plants. They possess a short stumpy breathing tube, and float head downwards, like the larva,^ of Culex. The adult insects are more or less striped or speckled black and white, and have plain unspotted wings. They bite chiefly in the da>' time, and often abound in woods and in the shade of trees. In America Stegomyia fasciata carries yellow fever. The Anophelines consist of about 120 known species, some of which carry malaria, and are always found in malarious places. The larva.' occur chiefl)' in water on the ground, particularly in water which stands or flows amongst grass or water weeds. Thus the}' abound in the weedy margins of rivers, streams, lakes, and ponds ; in small sluggish streams and streamlets ; in water-courses, drains and gutters choked with weeds ; in pools of rainwater l}-ing on grass ; in [:)its from which earth has been removed, such as the " borrow pits " by the side of railway embankments ; in cisterns and pits used for watering gardens ; in ornamental waters ; in hollows in rocks ; and in water at the bottom of boats, &c. Thus while the lar\';e of Cidcv and Stegomyia occur in an\' small collections of water, such as those which abound in and around houses, on the other hand the Anophelines are essentiall}- marsh Dtosqnitoes — owing to which malaria is always more or less connected with marshy conditions, and is called Marsh Fever, or Paludism. The larva; feed chiefl}- on the surface of the water — on which they float like sticks, and not with the head hanging downwards. When 14 (listurbcfl the}- swim away backwards on the surface, and sink to the bottom only when much alarmed. The\- have no breathing tube like those of Citlex and Stcgoniviin. The adults are speckled brown and white, or black and white ; and the wings are not plain but generall}' possess three or four black marks along or near the front border. When the insect is seated at rest on a wall the tail projects outward at an angle from the wall ; whereas the Cnlcx and Stegoiiiyia sit with the tail hanging downwards, or even nearly touching the wall. All these facts enable anyone to distinguish at sight both the larwe and the adults of Anophelines from those of Culcx and Stcgoiiivia. Anojjhelines bite chiefl\' at night or in the dusk — owing to which the malarial infection is generall}- accjuired at night. The}- enter houses, but also bite in the open in spots sheltered from wind. (4) Personal Preve?ttion.—l{ t\-\Qy can a\-oid it, people should not goto li\-e in known malarious places, or in the vicinit}" of marshes, or close to an infected native population. E\en in such however, the chances of infection can be much reduced by the careful use of mosquito nets. The net should not ha\-e the smallest hole. It should be hung ii/snh' the poles, when these are provided, and not outside them. It should be tucked under the mattress all round, and should nc\-er be allowed to hang down an}-where to the floor ; and it should be stretched tight, in order to allow ever}' breeze to enter, and not be hung in loose folds, which check ventilation. Those who can afford it shoukl protect the windows of the house with wire gauze, and proxide the doors with automatic closing arrangements. It is especiall}- adxisable to protect a room or a part of the \-cranda, for sitting in during the da}- or evening. I'un] a broad general rule, malaria causes from a quarter to lialf the total sickness in the tropics. Malaria can always be greatly reduced, or may even be extirpated, in any locality. Large marshes in populous places must be drained, deepened, or filled up. A proper permanent organisation must be established for dealing with the smaller breeding places of Anophelines, and for distributing quinine, especially to infected children. Other measures can be adopted where called for. The cost is likely to be more than recouped by saving in life, labour, invaliding, medical attendance, and hospital accommodation. The campaign will remove other mosquito-borne diseases as well as malaria ; and will tend to improve general sanitation in the locality where it is undertaken. 3. THE DURATION OF INFECTION. The foregoing sections show that we have acquired much knowledge about malaria ; but several points remain to be discussed. The discussion is the more necessar}- because these points, although of cardinal importance in connection w ith the art of [)revention, receive no adequate attention in text books. The first question is this : How long after a non-immune person becomes infected do the parasites remain in his blood, provided he receives no medical treatment and no fresh infection ? We must first ask : How long may they possibly remain ? In every case they certainly remain while the fever lasts ; that is, in untreated cases, for some weeks or months, at least. Sailors infected during a few da}-s' sta}- in a West African river come to Li\erpool after a month's journey at sea, and are frequentl}' found to be infected for weeks and even for months after their return to Liverpool. In such cases re-infection on board vessels is not likely, owing to the rapidit)- i6 with wliich moscjuitocs arc blown out of a steamship : and malarial infection in England at the present da}' is almost unknown. I ha\e found the parasites in several [)ersons after residence in England for six months : and in one case they were ctn'tainly found in Liverpool after four \-ears' absence from an\- malarious localit}-. Another case well known to me was that of m}- father. He had suffered much from malaria in India. In 1880 he left India permanentl}' and resifled in the South of England. In 1889 he informed me that he still con- tinued to have one or two attacks ever}"- year ; and a little later I witnessed one of these — a t\'pical attack with severe rigor followed by high fever, and without s\-mpt()ms of influenza or other disease. His blood was not examined. I ha\e also been told by three different persons that they continued to suffer from occasional attacks twenty years and uKjre after leaxingthe tro[)ics. In such cases microscopical verification is difficult to obtain owing to the fact that a large dose of quinine is generally taken at the onset of the parox}-sm. We have therefore the right to say that the infection occasionally remains for some years. The next question is : How long does it remain 01/ the avcraiirl That is to say, out of a thousand untreated persons remo\ed from possibilit}- of re-infection, how man}- will continue to have attacks after one, two, three }-cars, and so on ? I can suggest only one wa}- to obtain a repl}-. Taking Xorthern India, for example, we observe that the Anophelines do not begin to abound until Jul}' and disappear in Xo\'embcr or December. The admissions for malaria continue all the year, but show a great increase in September or October, that is, as we may expect, two months or so after the reappearance of the Anophelines. Hence we ma}' infer that the admission rate for malaria before the annual appearance of Anophelines is due chiefl}' to relapses occurring among persons infected in prexious }-ears ; while the admission rate after the ap|)ear- ance of the .\nophelines is due to relapses plus fresh infections ov re-infections. In other words, the minimum admission rate for the }'ear represents roughl}- the relapses onl}- ; while the difference between the maximimiand the minimum rates is caused b}- the new- infections. The Annual Reports of the .Sanitar}- (."ommissioner with the Go\-ernment of India gi\e al^uiidant material for this enquir}-. It will be seen that in station after station and ^•ear after \-ear, the 17 admission rate for Intermittent Fever tends to be lowest in February and March and to be highest in September, October and November, That is, the admissions begin to increase about two months after the commencement of the rains, and continue to increase with the accumulation of cases until November, after which a decline, due to recoveries, occurs. The October maximum may be from two to five or more times greater than the February- minimum. For illustration, I select at random the Native Troops on the North-West Frontier, Indus Valley and North-West Rajputana ; Returns (tables) for 1900-3, Table XXXV., Group VII. ' . ■ ■ ■ ADMISSIONS. . ■ ' :. . ; Average Year. Average , j, j^j ^ j^j^ j_ j_ ^ g. O. N. D. Total to i.ooo strength. -' -^ ■' strength 1900 ... 15,861 328 168 109 121 246 357 301 246 499 1,611 1,189 920 6,095 384-3 1901 ... 16,951 400 198 265 437 483 583 509 461 628 1,712 1,101 522 7,299 430-6 1902 ... 16,472 309 248 199 297 475 338 449 482 568 867 1,166 764 6,162 374 1 Average... 16,428 379 205 191 285 401 326 420 396 565 1,397 1,152 735 6,519 396-8 Here the average maximum in October is more than six times greater than the average minimum in March, and the increase must be due to the new infections caused by the summer hatch of Anophelines. Of course the difference is not always .so marked. In the south of India, owing to the warmer winter, the insects breed and infect more continuously ; and in other places, where there are streams, lakes or irrigation waters, they are not so dependent on rainfall. As a very rough estimate then, I am inclined to infer that after the six winter months, during which we may suppose tew fresh infections to occur, the ca.ses would tend to fall to about one- quarter the original maximum number. Suppose now that we could suppress entirel}' the next summer ri.se, and that the admissions for relapses continue falling at the same rate, namely to one-quarter every six months ; at the end of twelve months, the cases would be one-sixteenth the original maximum ; and at the end of eighteen months would be one-sixt>'-fourth of it, and so on. In other words half the cases tend to recover every three months, if no re-infection occurs. Thus out of i,ooo original cases, 500 would remain infected at the end of the first quarter ; 250 at the end of the second ; 125 at the end of the third ; and three or four after two j-ears. 1 8 The truth lies somewhere near these figures, but so man}' factors are concerned in the result that it is difficult to make a more exact estimate. For example, the Indian statistics refer to soldiers A\'ho were certainly given medical treatment ; and this treatment must have resulted in reducing the number of relapses, although it was evidently insufficient to cure the cases altogether. Again, if many of the patients ha\-e suffered from malaria in childhood (as most Indians have) many would be partialh- immunised, and the number remaining infected after a given lapse of time would be less than with people exposed to the disease for the first time. But the estimate of a 50 per cent, reduction ever}- three months ma}- be adopted for the present as a working h}'pothesis, which will at least serve to give precision to our ideas. 4. THE PARASITES BETWEEN THE RELAPSES.— If the infec- tion is not cured at once, the patient suffers from a succession of relapses with intervals of several weeks between each, the parasites being found readily in the blcjod during the relapse, but not so easil}' during the interval. Marchiafava and Bignami \\cre, I believe, the first to suggest that they enter upon a latent [e.^., an encysted) phase in the interval, but admitted that they could find no microscopical verification of this conjecture. Several writers thought that certain known forms of the parasites (the sexual forms) serve to continue their existence at these times ; and quite recently F. Schaudinn repeated the same speculation. There is, however, no need for it. M}- own position has alwa\s been that the parasites simply vary in numbers within the body, as the tubercle bacillus does. When they are numerous the patient suffers ; \\hen the}' are few he does not feel them. It is easy to estimate the number of malaria parasites in a patient b}' comparing them under the microscope with the number of red blood corpuscles. In severe cases the number of parasites may exceed 10 % of the number of red corpuscles. P"or example, we made a careful estimate in the blood of a soldier from Wacoas early this \-ear, and found that his parasites numbered 12 ^^ of his red corpuscles. Now a medium person of 150 lbs. (68 kilograms) bod}-- weight, contains about 25,000,000,000,000 red corpuscles ; so that this man must have contained about 3,000,000,000,000 parasites w 19 when his blood was taKcn. \\1ien there is less fever the parasites (exckiding the sexual forms, which do not produce fever) are much fewer. If there is only one parasite to 100,000 corpuscles, that is, on]}- 250,000,000 in the whole body, there will be little fever, and it ,ill be difficult to find the parasites at all in the small droplet of blood examined. Hence, when the parasites fall below this standard (which ma}- be fixed at this figure for a rough estimate), the patient will scarce!}' feel them, and the physician may scarcely be able to find them. If they number only a few thousands, they will not be discoverable ; and yet they will be amply numerous enough to keep the infection alive— just as a few rats in a ship will suffice to keep the ship infested. Later on the parasites may increase again, and reach sufficient numbers to produce another attack of fever and to be again discoverable by the microscope. As I have said, no one has yet succeeded in proving the existence of a resting stage of the parasites, though many attempts have been made. The task should be eas}- with the parasites of birds ; but in 1899 I searched many infected birds in vain— only the ordinary forms could be found. Moreover, with a resting stage we should expect to find relapses occurring after definite intervals— that is, in regular biological cycles ; but in my experience they occur quite irregularl}'. The explanation given above is sufficient and probable ; and no other one is required until it has been proved to be wrong. 5. CAUSES OF THE RELAPSES.— But it will now be asked, what causes the parasites to increase and decrease in the manner suggested above ? Probabl}' the same thing that causes the increase or decrease of other invading organisms — the varying resistance of the host. When the resistance is great, the parasites diminish ; when it weakens, they multipl}'. Probabl}- an}thing which weakens the resistance— fatigue, heat, chill, dissipation, other illness— tends to encourage the parasites and to precipitate a relapse. This is shown by a large number of observations. Probably every military surgeon who has dealt with malaria infected troops has noted that a heavy march or parade has been followed by numerous admissions into hospital for relapses. A costly item m military expeditions is the invaliding of infected soldiers who, though 2A 20 able to do the light work of peace time, break down with relapse after relapse of malaria when subjected to the fatigues of war. In 1889 I was in charge of a regiment of picked Madras troops sent by sea to Rangoon for active service in Burma. The voyage was oppressive and rainy, and most of the men were frequenth' wet through ; and dozens of them began to be attacked with t\-pical malaria while still at sea. African travellers frequently remark that their native carriers are attacked even during the first days of a journey. Ever}' planter knows that when his coolies are first put upon the heavy work of the season, scores of them suffer from fever. Engineers often observe the same thing. The frequenc}- with which relapses of malaria follow upon other diseases, such as pneumonia, influenza, t\-phoid, and venereal diseases, or upon child-birth, accidents, and surgical operations, is well known to the ph)-sician, and has resulted in the ancient aphorism that the intermittent tendenc)- is apt to be impressed on all diseases occurring in old cases of malaria. Most educated febricitants will aver that exposure to great fatigue, heat, or wetting will encourage relapses ; and probably a large number of cases of so-called sunstroke or heat- stroke are due mereK' to this cause, often perhaps aggravated b}' intemperance. For definite statistical evidence, however, I wish to call attention to a phenomenon which I have named the " hot weather rise" in the malaria admission rate. This is well seen in the Indian statistics referred to in section 3, even in the small table there given. Almost throughout India the admissions tend to increase slightly in the months of March or April, and this increase is so constant that it cannot be due to accident. To what then is it due ? The season is too earl)- for the rise to be attributed to fresh infections b}- Anophelines; and I can therefore place it onh* to the score of relapses caused b\- the rafjidl}- increasing heat of the tropical spring. Quite on other grounds I ha\-e long been forced to infer that great external heat is favourable to the parasites of malaria, both human and avian. Thus the obstinac)' of cases in the hot weather and the great improvement caused by removal to a hill-station or to Europe are well recognised by [)ractitioners. In 1898 I frequenth- took infected birds from Calcutta to the Himalayas and back again, and was always struck b}- the fact \\hich was ver)' inconxenient for my researches) that the parasites diminished greatly when the birds were 21 in the mountains and increased again when they were brought back to the phiins. Moreover, while i [ per cent, of the Calcutta sparrows were found infected in August, Dr. Daniels and myself had great difficulty in obtaining infected birds in December and January. I assume then that the "hot weather" rise is merely due to relapses encouraged by the temperature. It is easy to conjecture why the temperature should have this effect, on the ground that the parasites breed more rapidly in the hot weather in the expectation, so to speak, of finding the mosquito-host which bites only at that season. In tact, warm weather is their natural climate, and doubtless they can feel its influence even in the artificially heated medium in which they live. The malarial infection, then, is one which may last for a long time and cause many relapses, and I have dwelt at some length on this point because, as will be seen later, confusion in regard to it is apt to generate confusion in regard to the mode of propagation of the disease. 6. THE PROPER DURATION OF TREATMENT. — By treatment is here meant treatment with the specific, quinine, given in any of the methods usually adopted by practitioners. The question is, how long must it be continued in order to extirpate the infection entirely. It is a very important question as regards both cure and prevention, but is not sufficiently regarded either in text-books or in practice. In man\' of the former the drug is recommended to be given while the fever lasts and for a few weeks later. In military practice the soldier is often, or indeed generally, discharged to duty a few days after the temperature has returned to normal. The result is that the patient frequenth' falls sick again with a relapse, is treated again in a similar manner, and so has relapse after relapse, until he becomes a chronic febricitant, or a cachectic, or dies of black water fever. It is impossible to deny the frequency of such inadequate treatment in malaria because one is called upon over and over again to see patients who give this history. Obviously the iinal aim of treatment is not mereh- to reduce the present attack of fever, but to remove the parasites altogether ; and for this the patient must be kept under observation and treated for a considerable length of time. The period which I have alwa}'s suggested is three months in temperate climates and four in the tropics (in view of the observation that the parasites flourish more 22 readil}- in the latter). If a relapse occurs witliin these periods, the treatment must be recommenced from the beg^iniu'nL,^ I have known numerous cases cured by such a course, but still am not williiiL,^ to declare that it is sufficient for all patients. Needless to say, warnings against reinfection should always be given. Many practitioners think that intramuscular injection is so much more potent than medication by the mouth that with it a shorter course will suffice. The tjuestion arises here chiefl\- in connection with prevention (section 24) ; but also in connection with the treatment of coolies. U'lth them, as with soldiers, it is bad economy as well as bad medical practice to return men to dut\% or at least to release them from observation and outdoor treatment, before a complete extirpation of the infection has prcjbably been effected. Not only do they tend to be useless as workers, but they spread infection among the health}- ; and strict rules should be made on the subject in ever\' plantation and factory. 7. THE PROOFS OF THE MOSQUITO THEOREM.— The word thcorciii is used here in its correct sense as expressing not a mere speculation, but a bod}- of established fact. I wish now merely to summarise the proof's by which the mosquito theorem has been established. They are briefl}- as follows : — 1. Every stage of the life historx' of the parasites, not only in infected men, but in Anophelines of the proper kind who have been fed upon them, has been closely followed, described, and figured by many com))etent obser\-ers. 2. No such parasites have ever been found in Ano[)helines of the .same kind which have been fed onl}- on health}- [jcrsons. 3. Healthy persons bitten b}- infected Anophelines at the proper time liavc subseciuentl}- devcloi)ed the s}-m|)toms of malarial fever, and have been found to contain the parasites. 4. The same |)henomcna have been observed in the closcl}- allied malaria of birds ; and similar phenomena in the ca>e of man}- other parasites. 5. Where the Anopheline.s have been banished, as at Ismailia, the disease and the parasites have also disappeared. I might add that the great weight of all this evidence can perhaps scarcely be full}' appreciated except b}- those who have made a study 23 of pathology and parasitology, and have read the voluminous litera- ture of the subject. But the theorem has now been before men of science for nearly ten years, and has been so completely accepted by them that the public may safely follow them without misgiving. 8 DO OTHER INSECTS CARRY MALARIA. — But though the general theorem has been so definitely determined, we are not quite so certain regarding several details. If Anophelines can carry malaria, why not other insects ? First, we should note that not all, but only certain species of Anophelines carry it, and that according to some, only certain varieties of some of these species are effective. As a fairly general rule, animal parasites are very particular in their choice of hosts. Thus, no one has succeeded in infecting animals w ith human malaria, and the probability is that it will not exist m many kinds of mosquitoes. Between 1895 and 1899 I failed entirely in infecting several species of Ciilex and Stegomyia, though I made experiments on hundreds of the insects ; and these results were confirmed b>^ the Italian observers, by Stephens and Christophers, and by many others. But nevertheless such negative results are never absolutely conclusive unless enormous numbers of experiments are made, because it is always possible that some condition such as of temperature or humidity, may have been overlooked, or that the proper species or variety may not have been used. But there is a strong argument against mosquitoes in general being concerned, namely that from the oldest times malaria has been known to be connected with marshes, while many mosquitoes, such as most Cnlcx and Stegoinyia, do not breed in marshes as a rule, but in petty collections of water round houses. If these carry malaria, then malaria should abound everywhere, especially in towns, and not so exclusively near marshes. A good contrast is found in the case of yellow fever, which does abound in towns and not particularly near marshes— for the simple reason that it is carried by Stcgo))iyia. On the whole then, though we cannot say definitely that malaria is not carried b>' other hosts than Anophelines, yet there are strong reasons for this opinion. At all events we are fairly certain that all insects which carry it must be marsh-born, like the Anophelines ; so that the principal preventive measure of drainage is not seriously affected by the question. 24 9. IS MALARIA DUE TO THE SOIL ?— Even after the mosquito theorem was established, many capable medical men remained of the opinion that there might be another method of infection as well. The\- still thought (and indeed some still think) that the soil gives oft an infectixe effluvium, or miasma, which jiroduces malaria in those who inhale it. Let us examine this hypothesis with care. As stated in section i, the ancients knew that malaria abounds mostl}- near marshes. It was only reasonable to suppose, then, that the disease is produced b\' something which comes from the marsh. When Laveran discovered the parasites in 1880, everyone thought that the}- originate in marshes, but (as already noted) efforts to prove this by experiment were failures. \Mien the Anophelines were incriminated, and were at the .same time .shown to breed in marshes, the connection between the marsh and malaria was so well explained that there seemed to be no longer any need for the old miasmic hypothesis. Nevertheless it still received the confidence of many, for reasons which I will now classify and criticise. (i) Mosquitoes may abound ivherc there is no malaria. — This is quite true, but has no bearing on the case. When people talk of there being many mosquitoes in a locality they general 1}' refer to Ciilex and Stcgomyia, which so frequentl\- swarm in houses in the tropics. But these do not carry malaria, and their prevalence does not, therefore, affect the question. (2) Malarial infections may occur inhere there are no A )/oplielincs. So far as we kncjw, this is not true. In not a single case as yet has it been proved b\- competent observers that Anophelines are absent when fresh malarial infections arc occurring. I say competent observers, because untrained persons are not at all to be relied upon to find them. For exam[)lc, the Hon. Dr. Strachan and I once spent two nights at Ibadan, near Lagos, in a new house in which I did not see a single mo.squito the whole time. In the mosquito tra]) however (a net with a small hole or two and a man inside for bait), five or six, mostl\- .\nophclines, were captured each night ; so that the insects were reall\- very numerous. Again, in Mauritius, we failed for some weeks, even with the aid of a number of trained " moustiquiers, " to find the real culprits at Clairfond mar.sh (addendum 2). It is obvious that an "ordinary visitor " might easily be misled in circumstances like these. 25 We must not expect that in every malarious locality, the malaria- bearing gnats are the commonest. Their presence is often lost among swarms of other mosquitoes ; but nevertheless it is the few and not the many which work the mischief. In other places, as at Ibadan, the unwary observer, failing to see any mosquitoes at all, might go away declaring that there were none ; whereas, as a matter of fact, there may be many. The Anophelines are often very surreptitious in their visits to houses— they may pour in late at night and leave before day- break (as Stephens and Christophers first showed) ; and they are not such domestic insects as the Cnliciucs. Our moustiquiers stated that the Anophelines at Clairfond scarcely commenced feeding before 9 p.m. or later, either in verandas or in the open (addendum 2). Again, it is quite possible that at the moment when we visit even an intensely malarious place, few Anophelines at all may be there It does not follow that they abound equally all the year round. Even in the rainy season, they often appear, not continuously, but in swarms ; and between the swarms few may be visible. Thus, in one such place many years ago I obtained only a single individual, though the rains had commenced. Want of recognition of this fact has led even capable students of the subject to declare, without sufficient reason, that there is no constant ratio between the amount of malaria in a locality and the number of Anophelines. (3) Attacks of malarial fever may occur ivhere there are no Anophelines. This also is quite true ; and the fact has been cited over and over again in opposition to the mosquito theorem. For instance, persons may suffer from attacks of malaria anywhere — in Britain, on high mountains, and in the arctic regions. As we have seen, there is a rise in the malaria rate in India in April, before the Anopheline season has commenced. Attacks are very common in the winter, in the desert, and far out at sea. In Mauritius and elsewhere it has often been noticed that the disease is very prevalent in planta- tions and factories at times when the workmen undergo their most strenuous labour, as when furrows are being dug, crops transplanted, etc. Soldiers and coolies frequently fall sick when commencing active service and works of construction ; and all this without any particular or excessive prevalence of the Anophelines. Most of such cases are of course merely instances of relapse of malarial fever. The mosquito is responsible only for the initial 26 inoculation, not for the subsequent relapses, which, as stated in section 3, ma}' continue for years anywhere, from the north pole to the south pole. The occurrence of an attack quite apart from the Anophelines has therefore no bearing on the question unless it can be proved to be the first attack. But even this will not alwa}-s suffice to prove that the infection can be caused in other wa)'s than b}' mosquitoes. One often meets patients who give the following history : that they had lived long in a malarious place without ha\ing suffered from fever, but on returning to the coast and embarking for Eur(^pe, the}' were attacked while out at sea. On examining such patients, I have always found, either that the fever was not certainl}- malaria, or that the patient had been in the habit of taking quinine regularl}- when he lived in the malarious place. On embarkation he thinks himself safe and leaves off the quinine ; but without his knowledge he was probabl}- infected all the time ; and the quinine taken by him had sufficed to keep down the numbers of parasites without extirpating them entirel}'. Hence, when he discontinued the drug on board ship, the parasites began to multi[)ly rapidly and shortly gave him fever. As it was his first attack, he comes away with the belief that he was infected on board the ship, and is cited as a case in which the malarial infection was ])roduced where there were no Anophelines. It is i^roper however to admit that while most such cases can be explained in a similarly easy manner, we meet one occasional!}- which is niore diflicult. Hut I ha\'e never }-et met one in which explanation on the mosquito theorem was cjuite impossible. Every recorded case, even one recently recorded in the south of England, may have been bitten by an infected Anopheline. (4) Ma/arid is produced by digging. — In section 1 we saw that the theory of the marsh miasma graduall}- grew into the telluric hypothesis, according to which malaria is caused b}- a poison which exists in suitable soil and which escapes from it when it is disturbed ; and instances which apparent!}- support this idea are still cited. From what has just been said, the reader will gather that many of them are probably onh' rela[xses occurring among previous!}' infected workmen ; while others ma}' tiuite possibh' be caused in the usual way by Anophelines bred in marshes close to the spot where the soil has been disturbed. Both of these explanations are extremely probable in 27 the case of large operations such as railway and canal works, where hundreds of native workmen are crowded together, housed in rough tents or huts, and perhaps exposed to much fatigue and to the attacks of many mosquitoes. But nevertheless malaria may be caused actually by the digging, though not in the way suggested by the telluric hypo- thesis. I believe that this point was first cleared up by my own obser- vations made in connection with the Sierra Leone railway in 1899. Severe malaria had occurred along the course of the railway while it was being made. On visiting the scene we found innumerable puddles full of the larvae of the Anophelines by the side of the railway embankments, in the "borrow pits " from which earth had been taken for building the embankments, and even under the railway "sleepers." I saw the same thing in connection with the Lagos railway in 1901, and near the Greek village of Moulki in 1896. In fact the matter has now become a common-place with the students of malaria. Hence we must end by admitting that disturbance of the soil is really apt to cause malaria ; but that it may do so, not by liberating any telluric miasm, but by encouraging the breeding of Anophelines, and the occurrence of relapses among the workmen. We see, therefore, that there is little or no evidence in favour of the idea that malaria may be caused by other agencies than by the Anophelines. Let us now examine the strong arguments which may be cited against the hypothesis. I have already argued the case against other insect carriers (section 8). The case against the telluric miasm is very much stronger. In the first place, all experiments to infect men with air or water brought from malarious localities have failed (section i). Secondl}', if malaria were due to any particular kind of soil under certain conditions (as has been supposed) it should always be present where that soil and those conditions exist. But we know that actually it comes and goes. For example, it came to Mauritius in 1866, and to Reunion in 1867 ; it is still absent from Seychelles and Rodrigues, though favourable conditions for it exist in those islands (annexure i) ; and it has disappeared from Great Britain. But the soil and the climate of these areas have not changed. Thirdly, if the poison is diffused in the air it ought to affect everyone within a considerable area round the generating centre; 28 but as a rule the disease is limited to the immediate \icinit\- of the marsh (addendum 2). Fourthh-, the telluric miasm oui^ht to attack especially those who are engai^^ed in digging, but I have never observed that cultivators and gardeners suffer much more than their neighbours ; while, as a matter of fact, it is generally the children and even the infants who suffer the most. Lasth', tiie idea that the parasites can live in soil, water and air, as well as in men and mosquitoes is extremely improbable in the light of our general knowledge of parasites. The last is probably the clinching argument. Li\ing organisms do not possess independent properties ; but accord more or less in their structure, capacities, habits and life-history with other organisms. We arc cognisant of thousands of parasites of men, animals and plants ; and what we know of the parasites of malaria shows that they are not markedly exceptional. In fact they belong to a class of parasites which infect two hosts, one of wliich feeds on the other — as, for instance, [:)arasites of the deer and the tiger, the mouse and the cat, the ox and man, the ox and the cattle tick, and now man and mosquitoes. The general law is, therefore satisfied by the known life-history of malaria. We ha\'e no reason to expect another life-histor}^ for the malaria parasites in soil, water or air, any more than for the other parasites. Then again, every animal possesses only the limited powers which have been given to it b}- the evolution of ages, and for which it has acc|uired definite organs and habits of life. The mole burrows, the fish swims, the bird flies, the parasite occupies the higher animal or plant. Hut if this telluric hypothesis is sound, what remarkable animals must these parasites of malaria be ! They already possess a structure wonderfull}- adapted for their life in men and also in moscjuitoes ; but we must now expect that they are also able to burrow like the mole, swim like the fish, and fly like the bird ! To do all these things the\' must have the suitable organs ; and not onl\- this, but thc\- or their s[)ores must be protected against heat and cold and hosts of enemies in soil, water and air. If all this were true we should have to put the parasites of malaria in a special class by themselves, apart from the rest of creation. These reasons have now led pathologists and parasitologists (who can perhaps appreciate their weight better than others) to abandon 29 the telluric hypothesis as a likely one. There is no evidence in favour of it, and there are very strong arguments against it. The true theorem is obvious. The connection between malaria and the marsh, so long known to suffering humanity, is now fully explained by the fact that the Anophelines breed in the marsh. There is no necessity to believe that the germs also breed in the marsh. Malaria comes from the marsh, not because the germs of the disease come from it, but because the carriers of the germs do so. It is the same thing in the end. The ancient theory was quite right. Malaria h caused b\' a marsh miasm. The Anophelines themselves, the mosquitoes, are the march miasm. 10. WHAT DO WE MEAN BY THE AMOUNT OF MALARIA IN A LOCALITY?— It is very necessary to obtain perfectl}' clear ideas on this point. If we could examine all the people in a locality and could ascertain exactly where and when each patient was infected, we could then divide all the cases into two classes, namely, those who were infected outside the localit}- and those who were infected within it. We might call these classes respectively the imported cases and the indigenous cases \ and the ratio of the numbers of each class to the total population of the locality might be called respectively the imported malaria rate and the indigenous nuilaria rate. The imported cases may be ver>' numerous in some places, such as military stations, into which badly infected regiments are introduced ; or sanatoria or hill stations, such as Curepipe in Mauritius, where patients congregate for change of air or securit)-. Or the}- may be very few, as in rural villages, the inhabitants of which do not migrate much. If, then, we talk of the amount of malarial /-rtv in a localit}-, we include both classes, since the imported as well as the indigenous cases may suffer from relapses in it. But if we talk of the amount of malaria in it, we generally mean the amount of malaria which is or has been contracted within it — that is we refer to the indigenous cases onl}-. It is often difficult or impossible to distinguish whether a case was or was not infected within the locality. Careful enquir}' ma>' fail to determine the point ; and there are many cases which were originall}' infected without, but which have been cured and then 30 rc-infected within — so that if wc omit these from our list of indii,fenous cases we shall obtain wrony;' results. Ai^ain, man}' of our indii^encnis cases may have emiij^rated elsewhere since becoming infected. In many localities, however, unless people are especialh' attracted or repelled to or from them, the number of emigrants and immigrants w ill tend to be equal, "fhat is to sa}', on a rough a\'erage, as many patients will be leaving the localit}- as entering it ; so that the total malaria rate of the locality will represent fairh" accurateh' the indigoious malaria rate. The indigenous cases ma}' be further classified according to the dates when they were infected ; some may have been infected a month ago, others two months ago and so on. If we ascertain the number of persons infected in a }'ear or in a month, we can obtain what ma}' be called the afuuial or nuvitJily iiifectio}i rates of the localit}'. When we sa}' that a place is very malarious, we mean that its infection rate is ver}' high. When we say that it is ver}' malarious at a given season, we mean that its infection rate is \er}- high at that season — not necessaril}- at other seasons. These rates are difficult to obtain, and, in fact, can be obtained only after mathematical investigation. Similar rates ma}' be ascer- tained for all diseases ; and I have suggested the name pathoDictjy for this l)ranch of stud}'. As a rule in medical statistics, most of the considerations given above are ignored ; with the result that the statistics are often quite useless. We shall consider later (section 19) the best methods for measuring the amount of malaria in a localit}'. II. FACTORS WHICH INFLUENCE THE INFECTION RATE.— The infection rate \aries, not onh' in neighbouring places, but even in the same place from year to }'ear. It rose suddenly from zero to a high figure in Mauritius in 1866: and has long fallen to zero in Britain. What is the cause of these variations ? This (]uestion is so important as regards both the general theor}' of malaria and the subject of prevention that we must endeaxoiu' to obtain clear ideas about it by careful reasoning. The number of infections occurring in a localit}' during an}' interval of time (say one month) depends on the number of infected Anophelines ; which in its turn depeiids on the number of Anophelines which have bitten prc\iously infected persons. We can therefore calculate the former if we can calculate the latter. Let/ denote the average population of the locality ; ;///, the average number of infected persons in the locality during the first month of the enquiry ; and imp, the average number of these whose blood contains enough of the sexual forms of the parasites to infect Anophelines. Mere /// and / are fractions, since ;;// must be less than />, and imp less than vip. Next, let a denote the average number of Anophelines in the locality capable of carrying malaria, and ba the average number of these which succeed in feeding on a single person during the month. Here b must be a very small fraction, since probably many mosquitoes never succeed in biting men at all, and of those that do succeed only a few will have bitten a particular individual. Hence the average number of Anophelines which have bitten the suitably infected persons during the months will be baimp. Now if any of these insects are, in their turn, to infect human beings, they must survive for at least a week or more, in order to give time for the parasites to mature within them ; and by no means all of them will survive so long. Let s be the average proportion of Anophelines which can survive for that period ; then sbaimp will be the number of the infected mosquitoes which have survived long enough to infect men in their turn, where s is also a fraction. But not all of these will find opportunities to bite human beings again, though they have survived long enough to do so. Let / be the proportion which succeed in biting. Then fsbaimp will be the average number of infected Anophelines which succeed in infecting men ; and if each of these infects a separate person and only one person, the same expression will denote the average number of persons infected during the month. T\m?> fsbaimp not only gives the monthly number of infections occurring among the population /, but also shows that this number depends upon the factors /, s, b, a, i, m. The greater these factors are, the greater will be the infection rate. If w, the proportion of infected persons at the beginning of the enquiry, is high, the infection rate also will be high, but if /// = o to begin with, that is, if there are no infected persons in the locality to begin with, then there will be no new infections, because the Anophelines cannot 32 become infected — as at present in Britain. Ai^ain, if a, the total number of Anophelines in the locaht}-, is high, the infection rate will also be high (if the other factors remain the same) ; but if a = o, new infections will cease. The factors /, s,/, b, are likel\' to be fairh- constant and may be roughly calculated. Thus i denotes the proportion of infected persons capable of infecting Anophelines of the proper kind ; and we shall not be far wrong if we take it that, on the average, onh- one cjuarter of the malaria patients contain enough parasites ripe for this function; so that we ma\' put /=}. Again, s denotes the proportion of Anophelines which can sur\ive for a week or more, and will \ar\- with the number of enemies of mosquitoes present, the warmth of the weather, the abundance of the food, and so on ; but at a rough estimate it might be put at \ ; so that we ma}' write s=^\. The factor /" denotes the proportion of Anophelines which succeed in biting human beings during one month — that is, I supi^ose, during their a\erage life. It must be less than \ because only about half the Anophelines, the females, attempt to bite human beings, and certainly all of these do not succeed in their quest. Let us therefore puty^j. Lasth' h denotes the proportion of Anophelines which succeed in biting one individual. Now if y> is the human [population of the locality, and /' is the proportion of x^noijhelines which can bite an\- of these, then obvioush'-'- is the proportion which can bite only one person ; that is, 1?=^'— ; and as we have taken /=], then b— -^ .• Let us now consider an example. Let the population, / = LOt>(» ; let VI — h, so that ;;//, the number of infected persons = r)00. Then of these only one quarter will be able to infect Anophelines ; or /;;//>= LJo. Next suppose that there are 12,000 Anophelines {a) in the locality, or 12 to each person. Then since only { of these, or 3, are likely to succeed in biting, /'(?/////, the number of them which have bitten the Vl'j suitablx- infected persons, = o X L^o^oT-"). l^ut of these onl}' about ?, are likely to survi\e long enough to infect people in their turn ; that is, sba/m/? = 12'>. Lastly only about } of the survivors are likely to succeed in biting again ; so that the final residue of infecting Anophelines, given hy/sbatwp, amounts onl\- to 31-25. I f each of these bites a single and a different person, 31 people will now become infected. Thus the infection rate of the locah't\' tlurini;- the month will be '3T25 % of the population. If we adopt the values suggested above for the constants /, s,/, l>, namely, \, ^, \, ~J^- respective!}', we have, No. of infections ^ fsbaiinp = ^j-^ To obtain the infection rate per 100 of the population, we have to multipK' the number of infections h\ - — , so that : — ' P Infechon rate % = ^92 • ^ "2 * T ' ''^^S'lly ; that is to say, the monthly infection rate per 100 of the population equals roughly half the malaria rate multiplied by the number of Anophelines in the locality to each person. Thus in a village in which there are l,2o() people, 750 infected persons, and 3,000 Anophelines, the malaria rate is 0'6, the number of Anophelines to each person is 2'4, and the monthly infection rate % is 0*72. That is, if a person lives in the village for a month, his chances of becoming infected will be as 72 to 10,000. Such calculations as these, which ma}' appear far-fetched to many, are useful, not so much for the numerical estimates }'ielded by them, but because they gi\e more precision to our ideas and a guide for future investigations. Thus, \\hate\er numerical \alue the symbols f\ s^ a, i, in, p may ha\e, we see that the infection rate is dependent not only on two of them, a and ;//, as is often stated, but on all, and is therefore not so easy to calculate as may be thought. 12. CONDITIONS WHICH CHANGE THE NUMBER OF INFECTED PEOPLE IN A LOCALITY.— The number of infecting mosquitoes which succeed in biting again is fsbainip. If we adopt the values for /, s, b, i, suggested in the last section, this becomes -^rr^^r ■ ^'^P- Now, if all these bite different people, some Lv'Zp will bite health}' people and give them fresh infections ; and others will bite persons already infected. If, as before, nip is the number of persons already infected, then / — nip, that is, (1 — ;//)/>, will be the number of healthy people. Hence, by proportion, the number of the infecting mosquitoes which bite the healthy people will be (1 — m) '^ . nip ; and if each bites a different person, 3 34 and each person becomes infected, the same expression will denote the addition made to the number of infected persons in the locality at the end o( the month. Hut flurinij the same time some of the persons originall}' infected may ha\e recovered. Let us denote the number of these by j'mp, where /- must be a fraction. Hence, if the number of newly infected I)ersons, (1 — w) ' . ////. is greater than n/ip, the number of recoveries, the total number of infected persons will be increased ; but it will be decreased if the former is less than the latter. Thus the change depends upon whether (1 — w),Y)!; '■'^ greater or less than ;-. In section 3, I estimated roughly that half the infected people remain ill after three months. Thus \/^ remain ill after only one month, and 1 — '^'h, or 0-206;3, reco\er ; so that we ma>- write for a rough estimate, r = 0-2063. Thus the malaria remains unchanged if rt 0-2 , . ., iQo:;r = i ; ^'"'^^t is, it . ■ j^ _ 39;60 - : ...... p ~ \ — ni ' that is, if the number of Anoiihelines to each ijerson is about 40 YZTjii • ^* '''^' the original malaria rate, is very small, the rate will remain constant if there are not more than 40 Anophelines to each person. If it is high, say \, it will remain constant even when the number of Anophelines is doubled. If the number of Anophelines is higher or lower than , , the malaria will I — ;// increase or diminish, as the case may be. Of course the actual number 40 is onl\- a rough approximation, because we haveadoi)ted more or less arbitrar\- values for the constants y, s, /, r, and because we have made certain assumptions which ma\- not be quite e.xact. But, as I have said, the calculation is useful, not for its numerical results, but because it heljis to give precision to our ideas. It is often thought and said that, if the mosquitn theorem is true, malaria should exist where\er there are an>- Anophelines of the proper kind, and when this is found not to be the case, the theorem is doubted. Similarl>-, it has often been stated that anti-mosquito measures will be uselass because, as long as any Anophelines remain, the ;disease will remain also. j-Jut 3S these fears will now be seen to be groundless. The Anophehnes must not only exist but must be numerous, if the disease is to remain constant or to increase. The above calculation suggests that they must average at least 40 to each person during a month if this is to happen ; and if they fall below this standard, the malaria will begin to diminish. Whether the figure 40 is ciuite exact or not does not matter— the important thing is that there is and must be some standard, whatever it is. And a little thought will convince us further of this valuable law. Obviously, unless the number of Anophelines is large, the dangers and difficulties which confront them, will end by making them too few to infect numerous enough health)- persons to compensate for the recoveries among patients which are happily always occurring, and the disease will diminish and die out— as has frequently happened. It is possible to obtain the general malaria function or expression which gives the number of infected persons after the lapse of. r months, but the full calculation is scarcel}' necessary for this report.* It, how- ever, VI is small, and if ///.v/ denotes the number of infected persons r.t the end of .r months, then approximateh' ,11 ^p -(\ — /- + sif-'-\uip. This increases or diminishes wnen .r increases, if 1 — r + ^'f'^ is greater or less than unit\', that is, \{ sif- ^ is greater or less than r. If .s% /,/, r have the values already suggested, '">/> = (■^«^^^ + il^>"'^=(w-'>"'^ so that the malaria rate increases or decreases indefinitely if a is greater or less than about 40/. The function is what is called an exponential function, and changes slowl}' at first, and rai)ifll)- later. Thus, suppose that nip — 2 (so that the epidemic starts with onl}' two cases) ; that/' = 1,000 and a = l;i(>,000. Then ;;/ ,. = V o From this we find that the number of infected persons will be about 2, 3, 4, 7, 10, 15 in successive months, rising to 115 alter ten months, and 665 after twenty months. This explains the outbreak of epidemics * I hope to put.lish Ihe full analysis later. Obviously, deaths and other factors have been omitted from consideration in the above roUi^h esliniates. consequent on the introduction of cases from without, in places where there are enough Anopheh'nes. The same equation holds ap[)roximatel\-, even when ;// is high if a is comparative!}- small — that is, if the mosquitoes are reduced ; but in this case the malarial rate will fall. Suppose that in = h and /) = 1,000, so that there are 500 infected j)ersons to start with ; and let (t = S,000. Then ',7;, — - = -,. Hence the number of infected 192/ C persons in successi\-e months will be 500. 417, 347, 289, 241 ; falling to 64 in ten months, and 8 in twentw [n this case the malaria decreased even when there were as man}' as eight Anophelines to each person. If all the Anophelines are destro\-ed, ;//xp = H — y)xinp = ('7937)^^m/> that is, the cases dhninish according to the adopted rate of recovery (section 3) without an\- new infections occurring. If/ = 1,000 and //// = •")00 as before, the number of infected persons in successi\-e months will be 400, 396, 314, 250, 198, 157, 125 ; falling to 50 in ten months ; 5 in twenty : and 4 in two years. This fall is not much greater than that shown in the preceding paragraph ; so that the reduction of Anophelines from 6.000 to zero does not make ver\- much difference. In other words, in order to produce a marked diminution in the malaria rate, it is ni. * Compare page 148. -hi j^gj-g ^. _ Y^ . ^"^ ^ x_ . I92^yi- = about 168 ; and therefore - = 16. Hence we must reduce the Anophelines to one-fifth if we wish to reduce the malaria rate in the same proportion, that is, from a half to one tenth, in a year. If we are given two years for the reduction, the Anopheline ratio need not be less than 27, or one-third of the 80, which might be cheaper to effect. The following table gives the fall in the number uf infected persons, which, according to the formula, should occur if a is reduced to 2/, to/, to hp, and to 7.ero : — - . , ^. .1 A 1 9 "^ 4 10 20 a Months 1 -^ '^ ^ -^"^ = 2/ Cases 500 407-2 351-7 270-1 220-0 64-2 8-2 J, .. 500 402-0 323-2 259-9 209-0 56-5 6-3 = 1^ .. 500 399-4 319-1 254-9 203-9 52-9 5-6 396-8 314-9 250-0 1984 49-6 4-9 „ 500 Of course, the greatest fall in the cases occurs when there are no Anophelines; but even when there are two Anophelines to each person, the fall is not very much less. - 13. THE NUMBER, LENGTH OF LIFE, AND DIFFUSION OF ANOPHELINES IN A LOCALITY. The important ratio ^ denotes the average number of Anophelines to each person in a locality ; and we have seen that, if it falls below the critical figure of about -"^* the malaria rate will diminish. The number may 1 — ;//' , , , seem somewhat high; but we must remember the values \\e gave to the constants / and .-. We judged that only one-quarter of the Anophelines are likely to succeed in biting human beings; that onl>- one-third of these are likel)' to survive for a week or more;' and that only one-quarter of the remainder are likely to succeed in biting a second person. Hence onl)' one in forty-eight is ever likely to give infection. What reall}' is the average number of adult Anophelines in a locality ^ It is impossible to sa>-. Sometimes in a single room twentN" or more of certain species ma>- be captured ; at otl^er times they are difficult to find. At Clairfond, in Mauritius, our moustiquiers were searching for some weeks before the>' caught a single F. rosfa//s\ \\hich is the carrier there. As a rule, hi the houses of Indians about one Anopheline for each occupant may be a rough avera<;e for the insects actuall}- caui^ht. But the insects caught are probabl}- inostl}' the gorged and gravid ones, wliich ha\e recentl}' had a good meal, the majorit}' escaping out of doors in the morning. On the whole, it is quite possible that close to marshes there ma\- be a hundred or more Anophelines to each person. M\' experiment to estimate the output o{ MyzorJiviicJins nunHritiaiuis from the Clairfond marsh (addendum 2) showed that 1,000 sc|uare \-ards of marsh might x'ield 423 every night, or 12,690 a month during the season. As to the Av/i,'/// of life of mosquitoes. It used to be thought that they live onl\- for a few days, until I kept them alive b\- repeated feed- ings for a month or more in i S99. Since then StegomyicE have been keiJt in capti\-ity forsexeral months. .Anophelines are more difficult to manage, but \^'ill li\e for some weeks. Such experiments, however, gi\e little e\idence as to the question. What is the average length of life of the insects in nature? In captivit\- the\- are preserved from enemies, wind and weather; but, on the other hand, probably suffer from their imprisonment. The onh' criterion which I can suggest is a somewhat curious one, based on the length of life of their parasites Thus the parasites of malaria and }'ellow fever and the worms called Filaria bancrof/i iAkc from one to three weeks to develo{) in the insects. Ilence I infer that the average life of the hosts probabK' exceeds that period, as otherwise the parasites A\ould have little chance of completing their life c\-clc. Of course, large numbers of gnats hibernate and .estixate for months, but this suggests onl\' their maximum life. What we want to know is their average life. I fanc\' that a month niav be a good rough estimate during the most favourable season. /'/ir diffusion of uiosqiiitoes is a (luestion of the first im[)ortance in the prexention of mosciuito-borne diseases. When I first proposed in 1899 to rid toxvns of malaria b\' clearing them of the breeding places of mos(juitoes, many [)eo])le objected at once that the clearance would be futile, as the insects xxould certainU- rush in on all sides from the siu'rounding uncleared countrx' ; and for three xears no one could be ]:)ersuaded to tr\- the measure. In fact, an experiment was attempted later in India xxhich showed that, if anxthing, the clearance increased their numbers I In 1 903, however, the brilliant examjoles of Ismailia and the h'ederated Malax- States served to discredit such 39 ftncics. In ,904 . .-eaci a' paper (3) in which the :^f^^>^ was examined from a mathematical or rather logical ba..., and the following points were made clear. _ The diffusion of mosquitoes depends on lau-s wh.ch rcKul.ac the diffusion of all animals. f„.,tivpsind The animals within a given area cons.st partly of na es a d partlv of inrmigrants ; and the larger the area the smaller « be h proportion of imn.igrants to natives. If the population that . th^ ,un,ber of animals) is in a static condition n, a country he numb ofimmigrants and emigrants which cross a S-e" '-g 1 o boH^^e will tend to be equal and opposite-that is. the nt.mber "f " g- into an area will be compensated f..r b>- the number of cm.g.ants ""If we suppress the birth-rate withu, the area, the ,>optdatio„ ,„ust henceforth, after the death of all the natives, co-^.s^ -- > • • f . Tf the area is lame, and if such suppresMon does not iinniKTants. It inc aicci 1:5 10.1^^^-, i.:^„ :;:ci:ily attract the immigrants, the restdt uu,st be that the population x\ill be greatlj- reduced. . Ob^iousU-, if «e were to suppress the •--" '^"";-'" Mauritius without increasing the rate of immigration into '^o.^e^^ the emigration out of it, the human population -"W b astl^ reduced in time. A preciseK- similar thing ™-t happen uU^h must fall (see also 4). -1 difficult The rate of the fall accor'- centre w, aH „ r- If we clear a square of one mile wide, the deusi.> at the ' '"■ „ hr , " ■ at a quarter of a mile from the boundary it centre will be 2 /o - ^l "^ 41-^11 l 4p will be 1 1 yo ; and at the bounclar}- it will be 50'^',',. or one-half. Of course these mosquitoes found in the area after propagation has been checked within it consist entire!}- of immigrants. l^akc, for example, the case of a village of l,000 people collected within a circle of a j-mile radius in which the number of infected persons has been standing at 500. In this case, b\' last section, there must have been about 80 Anophelines to each person. Now, let us drain within a circle of half-a-mile radius round the centre of the village. Then the mosquito densit\- at the centre will be 3 %, and at the outskirts of the village 18 ;'o, or I4'4 to each person at most. Hence, b\- last section, the number of infected persons will fall as follows : — Months o I 2 3 4 10 20 500 472 445 420 396 279 156 But, of course, the ai'cragr number of mosquitoes in the village would be less than 18 to each person, and the fall in the malaria would be greater. Professor Pearson's estimates, like mine, are based on values of constants conjectured b}' m)-self on a basis of general probability, not determined b\' investigation. I have had no opportunity to make such imestigation : and no one else has attempted it — the entiuir}' would be difificult, and would demand mathematical as well as ex]jerimental skill. In the meantime, however, there is this excuse for adopting tentative \-alues — that the process enables us to form a clear mental picture of the factors concerned in malaria rate, and, perha[)s, to itnestigatc them in the future. Lastly, we should note that what are called constants above may be constant only for definite or even short periods. Thus the number of Anophelines \aries from season to season, and ma_\' increase or diminish in the same localit\- owing to the formation or disappearance of breeding pools. If it were not so, the malaria rate would tend either to \-anish or to reach the maximum ; but generalh' it increases and decreases at different times, according to Huctuations in the \alue of this constant. 41^ PART II.-MALARIA IN MAURITIUS. 14. SHORT DESCRIPTION OF MAURITIUS.- The island of Mauritius is situated in the Indian Ocean, about 550 miles east of Madagascar, and lies between the parallels 19 50' and 20' 31' south latitude and 57" 17' and S?" 4^' east longitude, thus being just within the Tropics. It is 36 miles long and 2^ miles broad, has an area of 705 square miles, and a coast line of about 154 miles. It consists of a table-land, of which the highest ridge, 2,300 feet above the sea, runs across the island in a N.K. direction. On either side of this ridge there are extensive plains, sloping down gently, or more abruptly in places, to the sea. Several small mountain ranges, of which the highest peak is 2,711 feet high, border the table-land. Near the sea, especially to the north and west, the plains have little elevation. Numerous small rivers cross the plateau from the medial watershed to the sea, cutting out deeper and deeper channels as they go. The mountains and parts of the plains are well wooded, but most of the surface of the island is under sugar cane cultivation. The geological formation is volcanic. The climate is that of tropical islands, warm, equable, and humid. The cooler season lasts from Ma)' to October, the warmer from November to April. The mean annual temperature at the Observa- tory (near sea-level) is put at 74-75 F-- ^1"'^ ^^an lowest being about 58-59' F., and the mean highest about 87-88 F. The prevailing wind is the S.E. trade wind ; and severe cyclones occur in the warm season. Rain falls at all seasons, but there are two rainfall maxima, one in February and one in August, and two minima, one in June and one in September. The mean annual amount and number of days of rain var}- with elevation and other factors from about 33 inches and 86 days to about 150 inches and near!}- 300 days— the rannest spots being at elevated points exposed to the S.E. wind. Heav\- falls occur with the cjxlones. Mauritius was discovered by the Portuguese in 1507, and occupied in 1589 by the Dutch, who, however, abandoned it in 171 2. Three years later the JM-ench took possession of it, and in 18 10 it was occupied by the British. In 1834 the slaves were set free ; in 1835 the importation of Indian immigrant labour commenced, and in 1865-66 malaria first appeared in the island. 42 At the census of 1901 the population was found to be 3/j,jj(), and was di\-ided official!}- into General Population (i 1 1,440), Indian Population (259,086), and Militan- and Shipping (2,810). The " general ])opulation " included whites, Africans, and half-castes. At present the population is estimated at 375,400 (1906). The capital, Port Louis, is also the principal seaport, and w ith the small surrounding district had a population of 50.342 in 1906. Recently the population has been drifting more and more to the cooler and healthier district of Plaines Wilhems, on the table-land, which, in 1906, showed a population of 66,157, gathered mostly in a chain of towns and villages along the raihva\-. Chief of these towns are Beau Bassin (750 feet), Ouatre Bornes (1,050 feet). Phoenix and Vacoas (1,400 feet), and Curepipe (1,800 feet). Other villages are Pam[)lemousses, Poudre d'Or, Flacq, Mahebourg, Souillac. Rose Belle, and Moka. most of which also are tending to lose man\- of their inhabitants for the same cause. The island has a network of railwa\-s, by which it can be traversed in abnut two hours. Scattered over the country there aie about a hundred sugar plantations and factories, each with a considerable population of Indian coolies ; and villages and huts of Indians abound almost everywhere, mostly hidden among trees. As might be expected in so old and civilised a colony, it possesses man}' good buildings, not only in the towns, but on the sugar estates and in the \illages. Man}- of the private houses, especially in Port Louis, are two-store}-ed ; but the majority are built on the model of the Indian bungalow, with a single floor and \erandas, and ser\ants' c|uartcrs behind, Ix'ing within a garden or " compound." The lower class of house is not so good, and is largely made of wood (though not raised on piles) ; and the lowest class is the mud hut of the Indian, or even a structure composed of old pieces of kerosene oil tins, the danger from c}cl(>ues being the reason gi\en for such j)oor buildings. Churches, schools, and other public institutions are numerous.* Plaines Wilhems district has an extrcmel}- good water supply from the Mare-aux-Vacoas, and other pipe supplies are given to Port Louis and several villages ; but wells and streams are largelv' resorted to. Lood is good and cheap. IIor.se and mule transit * Views of the plateau, of the houses, >.\;c., will be found in the I'iiologiaphs at the eml of this Report. 43- is expensive owing to loss of animals on account of trypanoscMiiiasis (surra). Night soil and rubbish conservancy is placed by the Health Deimrtment in the hands of contractors, and, in my opinion, is fairly well carried out. Labour is fairly cheap, though not so cheap as in India, as unskilled labour costs about Rs.15 a month. In 1906 the birth rate was 33-5 l^er mille, and the death rate 40 per mille. The Revenue and Receipts for 1905-6 amounted to Rs.i 1,169783, and the expenditure to Rs.9,91 5,863, of which Rs.749,827 was spent on the Medical and Health Department and on quarantine. At the census of 1901 there were 93,031 "houses" in the Colony, each containing 4-25 persons on the average. In the same >-ear the average densit)- of population was 534 persons to a square mile, almost equal to that of England. 15. THE OUTBREAK OF MALARIA IN MAURITIUS.-When Hernardin Saint-Pierre wn.tc his classical tale, Paul ami Virginia ( published in 1789), the scene of which is laid in Mauritius, there could have been no endemic malaria in the island. The author, who had lived there, pictured it as a country of pastoral romance, benign and healthy as it was beautiful. The hero and heroine, born in the island of white parents, and supposed to live in the Vallee des Pretres, very little above sea-level, were represented as vigorous ideal types of the European race. Vet the author evidentl)^ knew (,f the existence of malaria elsewhere, for he describes the death of the heroine's father from fever contracted in Madagascar, and says "he landed (in Madagascar) at that unhealth>- season which commences about the middle of October which prevails in that country for six months in the >-ear, and which will for ever bafHe the attempts of the European nations to cc^lonise that ,-^tal soil"— quite evidently malaria. No mention is made of a similar disease, or of similar results, in Mauritius., although an excellent description is given of the hot weather in December, including a reference to the " noise of insects which seek to allay their thirst in the blood of men and of animals." Yet we read that, when the Dutch first attempted to settle in Mauritius, they brought over numerous slaves from Madagascar. \\ho afterwards peopled the island. Unless Madagascar ^\■as newly - . 44 infected between tliat time and the date of Saint-Pierre's novel, many of these sla\es must [irobabl}- ha\e had fe\er ; and this fever should have s[)read in Mauritius if the conditions had been favourable. The introduction of sla\-es from Africa continued durin;^ the French occupation, and early last centui-y man\- Indians began to find their \\a\' to the island. In 1835 ^'i*-' ^\■holesale importation of indentured Indian coolies (with women and children) commenced. Infected reL;"iments from India and elsewhere ha\e frequently been introduced. Hence cases of malarial infection must have been brought in, not only by scores, but probabl\- b\- hundreds and thousands, from the beginning of the histor}- of Mauritius. Vet there is abundant e\ idence, apart from that in Paul ajid ]'irgi}iia, to jjrove that no endemic malaria existed there before 1865 — that is to sa}' that, though cases were introduced from without, the disease did not sjjread in the island before that date. Then, however, the great traged}- occurred, and in two \-ears the island of pastoral romance fell to the condition of West Africa or the Himala}-an Terai. It is not necessary for the purposes of this report to com[^ile a laboured account of the outbreak, and I will therefore give only the outlines. The literature of the subject is large. ShortK- after the commencement of the epidemic the government ver\' wisel}" appointed a commission of enquir\-, which published a bulk}- report in 1868 (6). Since then numerous publications on the subject ha\e appeared. An admirable sunnnar}- has been puljlished In- so great an authorit}' as Dr. Andrew Da\idson, who was in Mauritius at the time (7) ; and I ha\e read a \aluable criticjue in manuscript on the subject b\- I)r. A. Lesur. .After studying prol)al)l_\' most of this material, I conclude that endenn'c malaria on a large scale certainly appeared in Mauritius for the first time in 1866. The exidence in faxour of this opiin'on ma\' be summarised as follows. (T) Almost all medical writers on Mauritius [)rior to 1866 state definitel}' that there was no endemic malaria there. Some note ex- pressh that, when cases occurred, tliey were imported cases. Others remark with suri)rise on the absence of the disease, in \iew of the fact that all the conditions whicli faxour its pre\alcnce in other countries were present. Such testimon_\- is reali\- conclusi\-e in itself. We ma\' object that, after all, the writers may ha\e made mistakes of diagncxsis, 45 and that malarial fever mi<^ht reall)" have existed, but was returned under other names. Hut the total amount of fever of any kmd was small, and medical men of wide experience in the tropics must be credited with sufficient acumen to detect malarial fever, even before the discovery of the parasites. If the disease had existed even to a fraction of its present prevalence, the fact would certainly have been noted, not only b>- physicians, but bs" the general public as well. As a matter of fact, it was " conspicuous b>- its absence "-so much so that Mauritius was considered a sanatorium for sick officers from India and elsewhere. io) The medical statistics of the troops in Mauritius demonstrate the same fact quite clearly. I give the figures for malarial fevers (collected by Major Fowler;. ... .S,8-.4 .855 .B56 .S57 .858 1859 ^86. .86x n-fi 0-56 502 4-08 22-39 31-89 21-13 3-04 Admissions per I, ooo ... 6 U Sb o v^ ^ 1 n-n 00 0-0 o-o oo o-o i-7 o-o Deaths pel- I, ooo ... UU uu V„r. ... 1862 1863 .804 >865 1S66 .367 iSoS 91 -fi 2-52 1-65 2-06 21-32 1487-06 1243-26 Admissi.ms per 1,000 216 A ^^ i 00 1-45 0-50 0-55 0-0 0-56 16-61 10-0 Deaths per 1,000 ^ ^^ ^ ^^ ^ ^ ^ n , Q.~.o T C-nf-j IQOO TOOT Years 1S77-86 1BS7-96 i^':'7 '89'- '^"^^^ '? ° . • nVl-O 608-2 406-1 380-0 245-0 207 389 Admissions per 1,000 iiau duo ^ S-4 3-12 1-32 0-0 0-0 2-0 4-6 Deaths per 1,000 ^ "^ ^ ^"^ Strength 463 429 1902 1903 1904 1905 19°'^ '9°7 369 150 201 524 137-4 231-6 0-0 0-0 0-7 3-7 0-84 1-96 425 746 1,358 1,357 1,193 1,019 Years Admissions per 1,000 Deatlis per 1,000 ■ •■• Strenglli The small rises in 1858 and 1862 were due to relapses among troops newl>- arrived from India and China. The enormous rise in 1867 was due to the appearance of endemic malaria. The compam- tively high figure for 1905 was probably due to mobilisation of the troops during the malaria season. The death rate tends to fall more and more owing to improved treatment and to early invaliding. Dr. Davidson remarks:-" From 1823 to 1858, out of a strength varying, as a rule, from .145 to 2321, there were 51 admissions into the military 46 hospital for intermittent fe\er, which gives an average of li-ss than two cases per annum. During these thirty-five }-ears onl>- one death occurred from intermittent fever. During the same period there were only ten cases of remittent fever, with no deaths. It is doubtful whether during this period a single soldier was admitted for par()x\'smal fever contracted on the island." The admissions into the Civil Hospital at Port Louis told the same stor\-, there ha\"ing been only twelve for malaria during fortx'-five years. (3) Perhaps the most conclusive statistical evidence was that adduced by Dr. C. Mcldrum, F.R.S., C.M.G., in 1880-90 in quarterly reports (mi the relations of climate to disease in Mauritius (8). His argument is this. Previous to 1867 the deaths in the colon}- were fairh- evenly distributed from month to month, without an}- special rise at an}' particular season, except, of course, when various epidemics occurred. Sirice then, however, the whole character of the mortalit}' returns has changed owing to a marked rise in the number of deaths during the summer — that is, the malaria season. This rise is precisel}- what occurs in all \'er}' malarious regions ; so that the absence of it before 1867 shows that there could have been little malaria then ill the island (see also section 18, 4). .\lthough that disease did not exist, there were other fevers which prevailed, and which have somewhat confused the issue. Chief of these was a fever locally known as Bouibay fex'er. It was much studied b}- the commission of enquiry, and b}- man}- medical men later, especialh- Drs. Barraut and Lesur. It attacked chiefl}' the Indian population ; was most prexalcnt during the cool months ; was epidemic, " contagious," fatal, and pn.nc to relapses ; did not become chronic, and was not influenced b}- (juinine ; was accompanied b} enlargement of the li\er and jaundice; and was not particularly prevalent in marsh}- areas. Dr. Lesur thinks it was merel}- relapsing or spirochaete fever ; and Davidson suggests this, and also considers that many of the cases \\ere due to t}'phoid. In these views I entirely concur. Curiously enough, directly the epidemic of malaria commenced, the KcMiiba}- fe\er disappeared ; and Dr. Lorans has asked me to suggest an explanation. It may be that the disease really did disappear at that moment owing to accidental coincidence (and relapsing fever always comes and goes) ; but there is another 47 explanation, namely, that, when the great epidemic commenced, the two fevers were confused, and the minor one was lost among the numbers of cases of malaria, under cover of which, so to speak, it gradually died out. In those days, of course, microscopical diagnosis between the two diseases was not known. But it should be remarked that from 1862 to 1865 another fever seems to have appeared, which the Commission called the " spurious Bomba\- fever."' This occurred entirelx- among Indians, but was not contagious. At the same time Dr. Beaugeard, Medical Officer of the Civil Hospital at I'ort Louis, stated that "Cases of ague have been admitted occurring in i)ersons who had long been resident in the Colony, and in others who had never left the island at all— those latter, however few, still existed prior to 1865." Some of the medical witnesses before the commission also stated that they had seen a few indigenous cases as far back as (?) 1857. We must therefore admit the possibility, if not the probability, that scattered indigenous cases had been occurring in Mauritius prior to 1865. Dr. Davidson thus describes the onset of the great epidemic :— " Sporadic cases of malarial fever contracted in the island were observed from the beginning of 1865 and throughout the year. The}' were kw in number, and seem to have been chiefly confined to the marsh)' localities near the mouth of Grand River, or to the unhealth}' spots near the shore in Port Louis. A slight local epidemic occurred towards the end of the year 1865 among the Indian labourers on Wolmar Estate, a specially marshy localit}- on the sea- coast in Black River district. A considerable number of cases were also observed in November on Albion Estate, and near the church at Petite Riviere, at the latter place from the 15th to the 25th November." These cases attracted little attention at the time, but next year the epidemic broke out with severit>-. On Albion Estate there were 207 cases and 31 deaths, and on Gros Cailloux Estate 517 cases and 41 deaths, during 1866. Erom these it spread north and south. It crept up to Port Louis, Arsenal, Pamplemousses, and elsewhere during the first half of 1866. Southward it spread to Bambou and further. At the first invasion it occupied, according to Davidson, 13-1 miles of sea coast, and spread from two to four miles inland. After June it began to abate during the cool season ; but at the 48 commencement of tlie next warm season (1866 to 1867) it broke out with increased violence. Not only were the same districts affected worse than before, but the disease " invaded the whole of the west coast from south to north, passed round the northern extremity of the island, and extended down the east coast as far as Grand River S.E." At these extremities it was arrested b_\- mountain ranches. During 1867 the epidemic raged in the occupied territory, extending along sixty miles of coastline. Accounts of eye-witnesses of the fever at Port Louis recall descriptions of plague and cholera. One quarter of the inhabi- tants died during 1867 from all causes, and more than one-fifth from fever alone. The survivors " \\ere so prostrated by disease that the living were scarcely able to bury the dead." The highest mortality in Port Louis in one day was 234, on the 27th April 1867, and 6,224 fluring the whole month, out of a population of 87,000. Li the whole island, out of a population of 360,378, there were 31,920 deaths in 1867 ascribed to fever alone ; and the total death rate rose from :;2 per mille in 1866 to I20'5 in 1867. The actual malaria death rate was pr()babi\- about 90 jDcr mille. Those \\ho have witnessed malaria in its worst will not doubt these iigures.* The third wave, starting in November 1897, completed the concjuest of the island b\- occupying the south and south-east coast. Of course, it rca[)peared after the winter lull in the areas prc\iousl\- attacked; but in 1868 the death rate was only 10,923 for the whole island, about a third of that of the previous }'ear. Though it spread inland, especiall\- in the Flacc] district, it failed then, as now, to reach some of the highest areas of the table-land. At its worst, the fever was, as usual, of the remittent t\-pe. Man}- of the cases were certainly blackwater fever, a point which 'as I have not seen noted before) strongly supports the theory that that disease is purel}- malarial, since it does not seem to have existed previous!}- in the island. The usual pernicious paroxisms were common. I catmot find an}- statistics regarding the percentage of the deaths which occurred among children. For further details, Da\idson's book is tlu- most accessible (7). It is most necessary to note that a similar first appearance of malaria occurred in the sister island of Reunion, 125 miles distant, shorth- after the outbreak in Mauritius. Davidson gives the date as * Fever Enquiry Commission's Report, page 23. 49 1 869, but others adopt an earlier one. MacAuliffe, in his book "Cilaos" (1902), says that it commenced in 1865, owing to the arrival of the ship Eastern Empire with immigrants from Calcutta m December 1864. He saw the immigrants two months later, and thought they had recurrent typhus (? relapsing fever) ; but later the epidemic took the malarial type, and pre\ailed chiefl}' round marshes. He warned the inhabitants of Cilaos (12 14 metres high) against the marshes near the town ; but nothing was done, and malaria entered the locality in 1901-2, in spite of its altitude. Possibly the sickness of 1865 was nothing but relapsing fever, and true malaria did not enter until later. At all events, malaria appeared in both the.se islands almost simultaneously, while it still remains absent from Rodrigues and the neighbouring islands, and from Seychelles, in none of vvhidi Anophelines have been found. The Anophelines of Reunion hitherto recorded are Pyretophonts costalis (the deadly African and Mauritian one] and Myr.orhynehiis constani ; and malaria is extremely prevalent in the island at the present. 16. EXPLANATION OF OUTBREAKS OF MALARIA.— This astonishing occurrence caused much perplexit)- at the time among the more thoughtful students of malaria. It showed that the disease is at all events not due to any inherent poisonous property of soil, but rather that it might be caused b>^ some living organism capable of invading a country from without. Numerous hypotheses were proposed. Indian immigration was accused of introducing the poison, though a similar introduction by natives of Madagascar, as well as b>- Indians, had been possible for centuries. Certain ships which arrived in 1865 were suspected— but ships had been arriving for centuries. Floods and droughts were blamed— but floods and droughts had occurred for centuries. Disturbance of the soil in connection with the railway and other works in the Black Kiver district afforded a popular refuge from the difficult)— but it was pointed out that the soil had often been disturbed ; that the largest railway work, done in 1864, \\'as not followed by malaria, and that laying the gas supply in Port Louis in 1864-5 remained equally harmless. The mosquito theorem gives a ready solution of the problem. The appearance of malaria in a locality depends upon the introduction {cx) of Anophelines capable of carrying the disease, and (/;) of infected 50 persons (section 12). Hence the Mauritian outbreak can be readih- explained in either or both of two ways. The carrier of malaria in Mauritius is at present PyretopJiorus costalis, the dangerous African Anopheline, and it might have been introduced a little time before the outbreak. Mosquitoes do not easily travel far on board ships. They find difficult}-, I imagine, in obtaining water to drink and lay their eggs in, and are apt to be swept awa\' by the wind when seeking it ; while the movement and vibration prevent them from resting or feeding in comfort (as I haxe actuall}' observed on sexeral occasions). Sometimes, however, the}' endure these difficulties with success. On several ships, especiall}' river steamers, I have found Culicines breeding in water cans in the cabins, and once in flower vases on an ocean steamer. Possibl}- Anophelines may be equally successful, but onl}\ I think, on rare occasions, when there are open tubs on deck, or heaps of rain- collecting fruits or vegetables, and so on. For short vo}-ages Anophelines might certain!}' li\'e in the hold. I^ut for proof that P. costalis is not easih' transported in this way I may note onh' that it is not found in the Se}'chelles, Rodrigues, or the neighbouring- smaller islands, and that (fortunately) it has not }'et reached India. Ill other wcn'ds, if it can be transported at all on board ship, it can be transported onh' in a ver}' small percentage of ships. Hence it is quite reasonable to suppose that the ships which visited Mauritius from the date of its discover}- until about 1865 did not carr}' P. costalis, but that, at last, about that time, a single shi[) was unfortunate enough to bring them. Quite possibly the insects were breeding on that ship, and equally possibly the same vessel conveyed them to Reunion about the same time. \\Y^ must remember also that it is necessar}' for the insects, not onl}' to survive the v()}age, but to obtain a foothold in their new possession — a serious difficult}', which must tend to limit their diffusion still further. But, supposing that, on a single occasion, all these difficulties were overcome, the further course of events would be obvious ; the new country would be overrun by the invaders in the course of a }-ear or two. Next, if there are infected persons present, and the mos(]uitoes become numerous enough (section 11), health}- persons would be attacked, and an epidemic would begin. .All this is ver}- obvious ; but there is another possible explanation 51 of the appearance of endemic malaria in a country — which has not }'et been suggested. Suppose that the Anophehnes have been present from the first, but that the number of infected immigrants has been few. Then, possibh% some of these people have happened to take up their abode in jjlaces where the mosquitoes are rare ; others may have recovered quickly ; others may not ha\c chanced to possess parasites in suitable stages when they have been bitten. Thus the probabilit}- of their spreading the infection would be very small. Or, sui^ijosing even that some few new infections have been caused, }'et, b\- our rough calculations in section 12, unless the mosquitoes are sufficiently numerous in the locality, the little epidemic may die out after a while — for instance, during the cool season. And, if the number of infected persons introduced from out- side remains small, this state of things ma}' continue for years or centuries — the disease will fail to make headway and will die out. Now, suppose that the number of infected immigrants is suddenly greatl}' increased. Then much larger numbers of mosquitoes will become infected, and may in their turn infect more healthy people than the recovery rate will compensate for. Endemic cases will begin, will increase ; at first slowly, then rapidl}-, until suddenh' there will be a wide-spread epidemic. It is like the case of a careless person who throws lighted matches into a dr\- jungle ; the first matches may fall on rock, bare ground, or damp vegetation, but at last one will set the forest on fire. On the whole I incline to the oi^inion that the first explanation is the more plausible one in the particular case of the great outbreak in Mauritius and Reunion — I think that P. costalis was probably introduced a little previously. It is difficult to believe that, if this gnat had been present from the first, and had been as widely diffused as now, the disease would never have spread from the hundreds of infected Africans and Indians who must have entered the Colony during nearly three centuries. No very specially large immigration occurred before the outbreak. True, there were 20,283 immigrants in 1865 ; but as many or more had been introduced in 1843, 1854, 1858, and 1859 — in the last year 48,377 — without causing any epidemic. The occurrence of a fe\\' sporadic endemic cases (the " false Bombay fever " cases) would fit either theor)' ; and so \\ould the fact that the epidemic spread from 4A 52 a centre at Petite Riviere. Either, by the first theory, the P. costalis landed there, and spread rapid!)- round the coast ; or else, by the second theory, the first effective concentration of imported malaria cases occurred there. On the other hand, the facts that the disease occurred almost simultaneoush- in Mauritius and Reunion, and that P. costalis has not \-et reached the smaller neighbouring;' islands, are strongh' in favour of the first theor\'. Other local outbreaks, however, such as the recent one at Phcenix, I am more inclined to attribute to the second cause, or to both together. The whole subject of the invasion of countries b\- malaria is of great historical interest. There are many reasons for thinking that Greece and Rome were attacked in ancient times as ^Mauritius was in modern da\-s. The matter has been ably discussed by Mr. W. H. S. Jones, M.A. (ii). 17. FURTHER HISTORY OF MALARIA IN MAURITIUS. — From the date of its introduction, the disease has become permanently endemic in the lower parts of the island. Before attempting to examine details, it will be ad\'isable to mention the various enquiries on the subject which were made from that time up to the present date. In May, 1867, the Go\ernment apjjointed, as alread}' stated, a Fever Euqiiiiy Coinmissiou to report upon the causes of the outbreak ; and their report was published next year (6). It is a bulky xolume, containing a vast mass oi evidence, most!}- in the form of a qncstioiiaire in which numerous medical men and others record their observations and opinions on the epidemic. A full description is given by Dr. Barraut, the General Sanitar}- Inspector ; and the Commission adds its own conclusions and reconnnendations. Among the latter, I note, c<<\)Qcva\\\, re-afforestatioti, cleansing of rivets, "so that their \\aters niay run clear, and no longer stagnate in pools," and draii/cii^r or filling of marslics. The whole book is a very interesting one. In 1881 Dr. C. Meldrum, Director of the Observator\' at Pamplemousses, issued a large report (8) on The Relations of ]]^ea flier to Mortality and on the Climatic Effects of Forests — which is only the abstract of the full title of the work ! It is an able production, packed with suggestive remarks and figures well analysed. The author shows that before 1867 the mortalit)- in the island did 53 not possess the summer increase which it has exhibited ever since ; conchides that this increase is due to malaria, which in its turn is encouray,"ed by certain conditions of rainfall and temperature, and goes on to suggest a theor\- regarding c\xlical variations of death rates all over the world. He recommends drainage of marshes, re-wooding of mountains and slopes, draining of streams in the interior so as to create reservoirs, and strict sanitary rules. The report was apparently written by request of a sanitary commission which was appointed in 1879 "to enquire whether the General Board of Health had been successful in its attempts to check and abate the prevalent fever," and also whether the sanitar)- works performed by this body had given results commensurate with the outla}'. This commission seems to have concluded that, though the expenditure of the Board of Health had amounted to Rs. 1,596,488 during nine years (about i^ I 5,000 a year at that time), yet that the mortalit}' of Port Louis and the rural districts had been on the increase since 1870. In 1888 Dr. Meldrum wrote another report dealing with the subject (9). In this he states (page 20) that "the total death rate of the Colony has increased from an average of 28"03 for the five }'ears 1871-75 to an average of 32"88 for the five }-ears 1881-85, and the fever death rate from an average of I2'55 to an average of i8"50." He considers that the increase is due to malaria, and is not due to povert}', increase of population, or decrease of sanitar}' works ; that the increased expenditure of the Board of Health (now amounting to nearh' five million rupees during sixteen }'ears) has not been accompanied b}- an}' improvement in public health ; and that a similar increase in the expenditure of the Poor Law Commission from Rs. 279,000 in 1879 to Rs. 367, 546 in 1886 is partly due to malaria. Later he wrote a third report of a similar nature (10), bringing the figures up to date. In 1891-92 Mr, O. Chadwick, C.E., C.M.G., wrote a series of reports on engineering matters, including sanitary works, which have been collected in one volume (12). He emphasises many of Dr. Meldrum's remarks and recommendations ; but he objects to too man}^ trees in towns, such as Port Louis, because, as he remarks, " though afforestation is in every respect desirable, a town is not the place for it." He recommends underground sewers for Port 54 Louis. He docs not casil}- credit the hypothesis that malaria is due to turning" the soil, and insists on surface and subsoil drainage against that disease. Like Dr. Meldrinn, he suggests that reservoirs for irrigation could be easily constructed in the course of the streams. He gives other advice, with most of which I entireh- concur, and urges reorganisation of the public health administration. Dr. Daxidson's book GcograpJiical PatJiology (7), published in 1892, gi\es an excellent account of the malaria in Mauritius up to that date. He admits the connection between the annual increase of malaria and of rainfall, but shows that the former does not really depend on the actual amount of the latter — that hea\}- rain is not alwa}-s followed by heav}- malaria. hi Ordinance No. 32 of 1894-95 the Go\-ernment amended the constitution of the General Board of Health, created a Medical and Health Department, and amended and consolidated the laws relating to the public health. The Director of the Department was made president of the board, which now became purely consultative. Two sanitar}' wardens, possessing public health diplomas, were to be appointed, and numerous other changes were ordered. This organisation was certainly a great improvement, and much in achance of the same department under many other governments. It is remarkable, as exidence of the slowness with which new discoveries affect mankind, that Laveran's discovery of the parasites of malaria, made so long previoush- as 1880, had scarcely yet been put to scientific or practical use in the tropics, including ^Liuritius, and is hardly mentioned in most medical works, including Daxidson's book and Meldrum's reports. When, however, in 1897-99 the mode of infection b}- means of Anophelines was established, ^Lauritius almost led the wa}- in recognising the fact. As earl}- as May 1 900 ]\L Daruty de (irand[)re, Sui)erintendent of the Ahiseum, and AL d'Kmmerez de Charmo}-, Assistant Superintendent, rej^ort (13) that the>- have been following the work since 1899; that the}- have found in Mauritius five species of Culicines and three of .Anophelines ; and that one of these, /'. costalis, ''has the same area of dispersion as the malaria in Mauritius." The second }-ear the}' published a most excellent paper on mosquitoes and their role in the propagation of malaria and filariasis (14). The anatom}- and life histor}- of the insects were in\ cstigated in detail, and recommendations for prevention 55 made. I believe that Drs. Alfred and Aime Lesur had been among the first in Mauritius to study the parasites themselves. With great promptitude, Government appointed a second Malaria Enquiry Committee (1901). x'Vll this time the disease had been ravaging the coast and lower parts of the island, apparently unchecked by the expensive measures which had been taken — now waning, now waxing, now almost disappearing, now flaring up in epidemics. The wealthier residents had been practically driven out of these regions ; the beautiful houses of the planters could be occupied only during two or three months of the cool season ; their families could no longer enjoy rural life at the seaside, as they were able formerly to do. Every- where the villages became more and more deserted. Even the patient Indians sought the upper regions. Erom 5 per cent, to 30 per cent, of the labour in the malarious plantations was often incapacitated by fever, thus hampering further the resources of the planters, already greatly reduced by the fall in the price of sugar. Houses fell into ruins, or were removed part by part to healthier areas. The population of the capital, Port Louis, \\'hich had alwax-s suffered most of all, began to fall. The richer citizens now used it only as a place of business by day, returning to the plateau every evening, as the citizens of London retire to the suburbs. Even the houses were removed ; and everywhere one sees the ruined basements, overgrown gardens, deserted fountains, and mouldy gateways of the more prosperous past, now surrounded only by the poorest huts ot Indians. It is the classical picture of a great endemic epidemic. Plague and cholera visit a country and vanish ; but malaria and dysentery remain. Still, however, there was a secure refuge — the central table-land. But suddenly a part of this was invaded b}' a sharp epidemic — much to the consternation of everyone. The disease broke out in the summer of 1900-01 in a district of Moka, 1,400 feet above sea- level. Dr. Clarenc, the medical officer, reported promptly and ably on the occurrence, and the second Enquiry Committee was appointed. It consisted of Dr. Lorans (chairman). Dr. Edwards, C.M.G., Dr. Rohan, Dr. Clarenc, Dr. Bolton, Dr. A. Lesur, and M. Daruty de Grandpre. The suggestions of the committee were not only quite up to date, but were as good as could be made. Streams near Moka 56 cloi^ged with vegetation were cleaned out, and ([in'nine was distributed ; with the result that the epidemic ceased. Curepipe, Grandport, Savanne,and other localities were \isited, and similar work was started in them. Later on M. d'Emmerez de Charmo}- was appointed Technical Assistant to the Committee for the piu'j^ose of continuing" the stud}' of mosquitoes and their haunts, and for disseminating knowledge on the subject among the public. With the latter object in \iew, the committee concluded its reix)rt with a set vf instructions. The only defect which can be found in the work of this committee was that it was not generalised, nor continued long enough. ICarK- in 1906 the public alarm was intensified b\- another outbreak on high ground, nameh', at I^hcenix (1,400 feet), close to Curepipe. This epidemic, which is fully described b\' Dr. de Chazal ill this report (addendum 2), occurred in connection with the large Clairfond marsh, for the drainage of which Go\'ernment allotted funds, which, with the assistance of the Imperial Government, sufficed for the purpose, the work being nearh' completed when I left. In addition to the literature referred to abo\e, man}- other reports and papers on the subject have been published — notabl}' articles in the lUillctiii dc la Socictc Mcdicale dc l" lie Maurice ; a report on fever at the Beau Bassin Central Prisons, 1901 (15), and a correspondence on the high death rates on sugar estates, 1906 116). There is also, of course, a large official correspondence connected with malaria, showing the concern with which the disease has been viewed ; and, lastlx', we ha\e the excellent Annual Re[)orts of the Medical and Health Department and the Annual Reports on the Estate Hospitals — all giving evidence of work done by the Health and Imnn'gration Departments. 18. STATISTICS OF MALARIA IN MAURITIUS SINCE THE OUTBREAK. — The writings referred to above, together with the Annual Reports of the Registrar-General of Mauritius on Births, Deaths, and Marriages. gi\e us an enormous mass of figures on the subject of malaria in the colon}-. After a careful consideration of them, I conclude that it will not be advisable to attempt an exhaustive anal}-sis of them in this report. The figures ha\-e alread}- been gi\cn in the jDublications mentioned, and have alread}- been abl}- anah'sed 57 1904. 20,418 16-12 1905. 20,767 14-98 I goo. 20,976 16-48 by Dr. Meldrum and others. To repeat them at length would double the size of this report, without yielding information of corresponding value. I shall therefore discuss them now as bricfl\- as possible, and will then proceed to examine by other methods the present state ot malaria in the Colony— which, after all, is the important point. (l). TJic General Deatli Rates of certain Xoii-malarious Is/ane/s. — It is advisable to commence by noting the death rates in the Seychelles and other islands, where neither Anophelines nor malaria exist. For the Seychelles, we have — Years ... Population Death rates per 1,000 The average death rate for the seven x^ears preceding 1904 was i/'O/. Out of 359 deaths in 1906, 21 % occurred in infants under one year of age, 18 % in children under five years, 46 % in people under seventy years, and 15 % in people over seventy. In 1904 no fewer than five centenarians died, one having reached the age of 1 14 years. On two visits to the Seychelles, I was assured by his Excellency Governor Davidson, C.M.G., and by the chief Medical Officers that the deaths are rigorously registered and the vital statistics well kept. The following table gives the deaths in a number of non-malarious islands under the Mauritius Government : — I'c.fmlatioii Deaths Islands. Rodrigues Diego Garcia ... Agalega Peros Banhos ... Coetivy ... Salomon... Six Islands St. Brandon St. Jean de Nove Eagle Island I'dpulatioii at Census 1901. 3,437 526 372 184 143 119 117 87 75 74 5,134 1902. 72 14 18 7 11 3 4 2 1 1 133 1903. 69 18 8 2 3 4 3 7 2 1 117 1904. 64 12 8 2 4 6 2 1 5 104 1905. 29 18 7 6 5 3 2 8 1 3 82 1906. 98 9 17 5 3 3 6 6 2 6 155 Average Death Rate per 1,000. 19-3 27-0 31-2 24-0 36-4 32-0 29-0 55-3 16-0 43-0 31-3 The death rates are slighth' too high, as they are computed on the population for 1902 onl}' ; but still they show much higher figures than Seychelles. To what is this due ? On studying recent reports bv Drs. Rolton and Keisler, I find that there is a considerable degree 5S of sickness on man}- of the islands, including beri-beri, infantile tetanus, dysentery and diarrhoea, ovarian and uterine diseases. Sec, while there seem to be no full}' qualified medical men on most of them. At Se}xhelles and at Rodrigues, however, where the death rates are low, medical advice is accessible. Of course, there is considerable statis- tical error for the lesser islands, owing to the smallness of their population, but I think that we ma}- attribute their mortalit}- largel}- to insufficient medical attendance. (2). 7/ie General DeatJi Rate of Mauritius. — Dr. Meldrum has carefuU}' compared these statistics with those of Mauritius. The annual death rates of Rodrigues and Seychelles from 1872 to 1880 averaged I5'8 and 20'5 respectiveh'. In Mauritius, from 1804 to 1824 inclusive, the average white population was 7,106, with a mean death rate of 1 8*89, and the average " free population " (exclusive of slaves) was 9,419, with a mean death rate of I2'53. Thus the total mean death rate was I5'26. For the five }'ears from 1825 to 1830 the average population, exclusive of slaves, was 24,502, and the mean death rate was 2r44. All this time deaths among the sla\-es were not recorded. In 1829, however, there were 18,019 slaves, and these had an estimated death rate of 34" 5 3 — much higher than that of the whites and free coloured people. After 1831, according to Meldrum, the deaths among the slaves were registered, and the}' were emancipated in 1834. From this point, then, the registered death rates were higher. The following table gives them from 1831 to 1906 per 1,000 of poi^ulation : — ... iS-!i 1832 i8^3 1834 iS:;5 1S36 1837 tS^B iS;g t^^m Me.-in. ... 26-8 31-3 27-4 39-8 360 31-0 37-2 30-7 390 300 32-9 1S41 1S42 1S43 T?44 1S45 1S46 1S47 1S4S 1S49 1S50 Mean. ... 41-5 42-4 34-6 584 39-5 32-7 29-3 26-4 30-8 31-5 36-7 ... 1S31 i8t2 iS:,; i?S4 iSs."; 1S56 1S57 "SsS iS^9 i?6o ^teall. ... 26-5 28-1 29-6 84-6 33-0 50-6 26-1 28-1 309 31-6 36-9 ... i86i iS6j iS6; ;.mi4 1865 1S66 1S67 186S iSi^g 1S70 Mean. ... 31-1 41-5 34-8 341 33-4 32-1 120-5 56-7 35-0 22-6 44-2 1871 1872 1873 1874 1875 1876 1877 1878 1879 18S0 Mean. .. 25-6 26-8 33-7 29-5 24-9 27-5 296 27-2 32-1 28-1 28-5 ... 18S1 iK£j i>,-.3 1SS4 1SS3 18S6 1887 18S8 1889 1S90 Mean. ... 29-9 350 35-5 31-2 335 28-9 34-4 30-4 33-7 343 327 N'ears De ath rates Vears I)c ath rates Years I)c ath rates . N'ears Death rates Years Ik •ath rates Years Dl :alh rates 59 Ye.rs T89, 1S9. 1S93 1894 1S9-. ^896 ,897 1S9S :8o9 1900 Mean. I,,,(h rates 272 38 4 40-9 29-0 37-1 41-9 29-5 31-9 34-8 34-8 34-6 Ye.rs .. >9- ■*- '^cs ..04 1905 1906 - - - - ^ean. Death rates 40-3 34 39-9 32 2 40-6 40 ----- 37-8 Mean of 76 years ... 35-4. The mean annual death rate for the 36 years from 1831 to 1866, before the epidemic of malaiia developed, was 35-3, and for the 40 years from 1867 to 1506, since malaria has been present in the island was 35-7-almost the same. It might therefore be mferred that malaria has had no effect on the death rate ; but this inference can only be accepted if it can be shown that no influence has been at work to counterbalance the influence of malaria-that is, to decrease the death rate, while the malaria has increased it. ; Comparino- the Mauritius death rates before the development of malaria in 1867 with those of the lesser islands, we observe that they are not verv dissimilar. Mauritius was then probably in much the same condition regarding medical assistance as the islands are now m. I suspect that fulh' qualified medical assistance was not always avail- able and know that what was available was not nearly so expert as at the present day. Probably much loss of life occurred at childbirth, or owing to smalli)ox and undeveloped surgery, and the sanitary organisation was certainly immature. Many .serious epidemics swept the colony. In 1 8 ^7-4° there were ei^idemics of measles and smallpox ; in 1841, 1842, 1844, i«4S epidemics of smallpox and relapsing fever ; in 1854, 1856, 1861-63, epidemics of cholera-all of which must have creatly'swelled the death rates in the days before malaria. Since then so far as I can ascertain, there have been only minor epidemics of measles and influenza, while the plague has caused only about =; 000 deaths since 1899- I cannot find (in time for this report) when compulsory vaccination was introduced, but it must have made a lar'j-e reduction in the mortality. " On examining the figures, we find that, after the great rise m mortahtN' during 1867 and 1868, due to the epidemic of malaria, there was a most marked decrease, the death rates for the whole decade 1871-80 averaging only 28-5. This is a phenomenon frequently seen after severe epidemics. As Meldrum remarks, "Many persons died who, if there had been no epidemic m 1867-69, would pn.bablN' have died in 1870-72," or later. But there 6o are other explanations. The great mortal it\' during the e[jidemic was largel}- due to the fact that the suppl}- of quinine ran short. Later the drug was poured in, and taken widely. It was e\identh' not gi\-en in quantities sufficient to exterminate the malaria in all the patients, but it must ha\e saved, from then up to the present, many thousands of lives. Lasth', there was probabh- a great development of natural immunit}' among the survixors of the great epidemic. The assumption that malaria has had no effect on the mortality since 1868 implies, therefore, the assumption that the whole of medical science and practice, \accination, quarantine, quinine, and sanitary organisation ha\e done nothing since that date to reduce the mortalit}'. More correctly, the matter should be put in this wa\' : that, since the death rates now are much the same as they were before malaria entered the island, the effect of the disease has been to counterbalance all the results of medical and sanitary science diu'ing the last fort}' }'ears, put together. After all, the remarkable fact remains that, of the four neigh- bouring islands, Se\'chelles, Rodrigues, Mauritius, and Reunion, the first two, which ha\e no Anophelines and no malaria, possess a death rate of less than 20 per iiiillc, while the other two, which possess both, have a death rate of 35 and more, or about double. (3). Monthly l^ariatioii in the Deaths. — As a general rule, in malarious countries the admissions for malaria and the total number of deaths tend to increase largeh' in the rain}' season ; but in non-malarious countries this \-ariation does not occur with regularit}-. In the following table I give the average monthly deaths from all causes (a) in the Seychelles during three }'ears, 1901, 1902, and 1904; (/;) in Mauritius during 1861-66 (excluding 1862 before the entr}- of malaria; (r) in Mauritius during 1870-89, that is, for 19 \ears after the entr}' of malaria; and (c/) in Mauritius during three recent years. Avorasc Populitioii. Seychelles 1901-04 19,442 31 28 27 30 26 33 Mauritius 1861-66 345,27 Mauritius 1870-89 353,958 790 809 1.005 1.043 1,118 1,059 1,004 Mauritius 1904-06 376,974 1,012 981 1,307 1,314 1,357 1,262 1.597 1,284 1,125 1,089 1,285 909 J. F. M. A. M. 31 28 27 30 26 003 936 987 920 972 J. A. s. 0. X. n. 30 23 26 27 26 25 970 971 947 970 910 967 ,004 893 783 759 718 740 6i If „e divide the highest figure in each ,.f tl,ese hnes by tR o«e^ figure in the same line, we obtain the fractions ViS. '■ .°, > 'S,, and . ,6 t,; first two for Seychelles and «-"''- '-f™l-"f^"";':'^" two for Mauritius after the entry of malar.a. That .s to sa> the ratio between the highest and lowest monthly deaths tend to be ratio between L „ Meldrum -'ave statistics to show greater in malarrous places. Ui. Meldium „a^ , j that the -reatest mortalitx^ tends to occtn- about two m.ntths afte, the K :-^t tainfall. This ,s now easily e.planted by the ,mpe us g,v to the breeding of mosquitoes by the rants. A few - ^ -^;" >„ new infections would be produced by them, causntg o, accele.atn,, deaths a few weeks later still. .u.ili.pd com- (,) T/n- Declared Fever Mortality. - \^^ eve,> cml.sed coni .un^t* at the present day deaths are registered f^^^'^^^ make the total mortality returns fairly rehable ; but ';";;- matter regarding retm-ns which attempt to gne accurately the vauous ause oT death. Even where only qualified med.cal men are pe mitted to furni.sh death reports, the sources of error are n„merot,s M Zpatients die from a comple.. of cau.ses ; and others are not seen Tv a medical man until they are /« «V.««/., or even unt.l after death- such be g particularly the case with children, whose deaths cons ,tue such a large proportion of the total. In n.a,arious countnes deaths IZl min! dseases are apt to be returned under the headntg o e«r l^U-lh- b^■ unqualified registrars, thus swelling the declared ! mo tahty-; while, on the other hand, many deaths from ma ar,a are eZ ed t nder the headings of secondary complaints wh.ch hav 1 y "b- l-"pitated the fatal ending-thus reducng the declared efmonahty.' On the "•"•'e- ^'^en, the fever deat rates are vy apt to be unreliable. In Maur.tms, howeve, , «.th .t en e Xulation and large qualified medical staff, the -t ..... • ikely to be less than in an>- other trop.cal count, I have seen 'c di g l.«>ia : and wc ntust remember that the factors ju.s^ :e,;Uoned, which tend to ntcrease or decrease the error, must also tend to neutralise each other. The foll<.ving figures give the average monthly fe^ei deaths T^Iauritius during two sets of years :— ^^^^^ ^. I I \ ^ O. N. TJ. Totals. pgr'i.ooo. 62 They agree ver}- closel}-, and show a distinct seasf)nal \-ariation. Th.c fever mortalit}- is least in Xoxeniber and i^reatest in ihe autumn months, as usual. This fact itself gives strong evidence in favour of the view that the fever returns in Mauritius are not as unreliable as might be supposed. Had there been very great error, the pnjbability is that that error would have been ecjuall}- distributed over all the months, so that the knf)wn malarial seasonal \ariation would not have been so apparent. J^ut we find that the maximum monthly deaths are twice the minimum, as might be expected. Of course, in a disease which relapses so frequentl\-, deaths ma\' occur long after the infectixe season ; while chill}- weather kills many cachectics — facts which account for the continuance of some deaths during the cool season. The sets of \-ears just gi\en correspond with the two latter sets given in the previous table. By subtracting the fever deaths from the total deaths, we obtain a remainder of deaths declared not to be due to malaria. 1. F. -M. A. yj. h ]. A. S. O. X. D. Tot.-ils. '^^^'^^ per 1,000. 1870 89... 397 372 427 414 445 458 486 463 414 401 383 389 5,049 14-3 1904 06... 640 553 645 641 691 697 1.269 979 756 739 964 571 9,145 24-3 The sudden rise in Jul}- in the last line was apparentl}- due to an outbreak of influenza in 1906, which carried off a number of old and debilitated persons. Excepting when such epidemics occur, the non -malarial deaths show no such marked seasonal variation as the malaria deaths do. As Dr. Meldrum demonstrated, this absence of seasonal variation was the characteristic of the total deaths in the Colony before malaria broke out in it. There is, however, alwa}-s a slight summer increase owing chiefl}- to dysentery and diarrhoea, and a winter increase owing to influenza, chest affections, and so on Tables I and II give the population, deaths, declared fever deaths, and other necessar}' details, for man}- }-ears. During the seven years 1900-06 the declared fever deaths averaged 5.3S4 per anrimn, or jro "„ of the total deaths, anfl i4'o /><';- /////A- of the total population. (5). Cases of Malaria adiiiittcd into Hospitals ami Asvluins. — There is an immense amount of statistical material on this subject. I propose to epitomise it as briefl}- as possible. The following table is taken from the Reports of the Director, Medical 63 and Health Dei«,-tment. It yives the total achnissions into the variots govemlnt hospitals and asyhuns (n.unbeting fontteen m ,906), artd also the nt.mbe,- of admissions due to malar.a and the ninnber of deaths during the seven years 1900-06 1006. Total. Years TQOI. U,02. 1903. 1904- '9°5- ^^^^'^^'^^^f . ' fs \82 3 360 4.788 3,039 5,123 3,674 27,014 Malaria admissKms ...2,848 M« , ^^ ^^ ^^ ^^ ^^ ^^g Malaria deaths ^^'^ ^^^ ^^^ ^^^ ^^^ ggg 672 3,419 nlargement of leaths from nient of spleen. Maiariauc.... ... ^^^ ^^^ 3^5 669 67'^ ^M^ Enlargement of spleen ib^ ^^ ^^ ^^ ^^ ^q 140 Deaths from enlarge- 2 The average total annual admissions were 18,761 the average Ihnissions for malaria (as given above) were 3,859, and the averag deaths for malaria in these institutions were 6+-1 a y-ear. the e ntage of admissions dt,e to malaria was .0-6 "^ and the percentage of deaths from malaria to admissions for malana was 1-66 or onlv i6 in a thousand. r u ' u of This case mortality occurred in hospital in sp,.e of the be t treatment. We must not infer that U would be equally ow outside hos^tal, especially among the poorest classes and the children who, a 'witnessed myself, often take no treatment at all. NevertheN^ss it su<,.^ests that the declared mortality from fever m the colony must be tot high. The Hon. Dr. I.orans makes some pertinent remarl^ on this subject in the report for ,906. The case mortality was I o /„ in that year : and applying it to the number of deaths attributed o malada in the returns, we should have to admit that, according to the same ratio, there were 582,700 cases of the disea,se m the island durinc the ^.ear-about three attacks to every two persons. Certain y he rndian' admissions for malaria do often exceed half the strength, or sometimes the whole strength, even among troop.s ; but this is onlv at isolated station.s. r j ., - It seems that since ,899 the ,„,•,//,,,/ certiHcation of deahs was more generally and systematically enforced in two of the districts Port ^ouis and Plaines XMlhems ; with the rcsuh that the dec a ed malaria death rate fell at once in these areas to a fr-'-'Y 'l^^ former figures. In Table II, I give Dr. Lorans useful table bowing the annual total and malaria deaths m the various d stricts for eleven years. For example, in Port Louis and Plaines 64 Wilhcins in i (S96 the malaria dcaUis were about half the total deaths ; but in 1904 the}- fell to about one-sixth and one-ninth of the latter, respectively. More exactl)-, the malaria deaths durint^ 1896, 1897, and 1898 were 45'3 "j of the total deaths; but during 1899- 1906 the}- were onl}- 25'2 % of them — by which we may infer with some degree of probabilit}- that before 1899 20 % of the total deaths had been wrongly returned under the heading of malaria. This therefore would bring down the average declared fever mortality from 31*0 % of the total mortality to onl\- i ro % for the whole island during the seven }'ears 1900-1906. Hut we must now turn to an item in the last table not }^et considered, namel}- the hosjjital cases and deaths due to enlargement of spleen (with which I have included the small proportion of cases of splenitis). These have not been previoush- added to the malaria cases ; but, for reasons which will be given in the next section, I infer that the}' should be. They make the serious addition during 1900- 1906 of 3,419 hospital cases and 140 hospital deaths. The total malaria cases now stand at 30,433, or 23-2 % of all the cases ; and the total malaria deaths at 589, or r935 % of the malaria cases. This puts the hospital case mortality of malaria in Mauritius at nearl}- 2 %. As will be seen in the ne.xt section, the cases of enlargement of spleen treated in those hospitals are only a minute fraction of the cases existing throughout the island ; and the same thing evidently holds regarding the cases of fe\-er. The total number of deaths in hospital given in the abo\"e table was 8,221, and the deaths from malaria, 589, or yi %. Supposing the same ratio were to hold for the whole island, then the malaria deaths would have been onl}- 9,324 for the seven }-ears, or an a\-erage of ],332 deaths a }'ear, instead of the a\erage of 5,384 malaria deaths in the general mortalit}' reLurns — a great difference. But we must again remember that the deaths in hospital are not likel}- to be so great as those outside. (6). Cases of Malaria attending the Hospitals and Dispensaries. — In addition to the patients treated inside the various hospitals, a great number attended them and the dispensaries (^numbering twent}--eight in 1907) as outpatients. The Director of the Medical and Health Department (Dr. Lorans) was kind enough to collect for me the 65 number of such attendances for malarial disease during past years ; and I give the figures in Table III. Only a few of the institutions have records extending further back than 1H78; and I have consequently taken the statistics only for the thirty years from then to 1907 inclusive. Altogether 403,918 cases of malaria visited the institutions during that period, averaging 13,464 a \'ear — though of course not all these cases were different persons, man}^ attending for medicine over and over again. During the last seven }'ears the attendances averaged 2^,fil'/ a year. The figures do not always indicate the local prevalence of malaria, because many of the patients come from a distance. For example, at Moka, which is generalK' healthy. Dr. Clarenc states that many patients visit the hospital from Pailles, which is unhealth}'. So also the Curepipe dispensary is attended by many from Phcenix and Black River. During 1907 the total attendances at these institutions for all causes numbered, according to information given me by Dr. Lorans, 79,053, while the attendances for malarial diseases alone was 28,294, 01' 35"8 % of the total attendances; a very high ratio. Dr. Lorans' figures separate malarial diseases into fever, cachexia, and enlargement of the spleen. On examination, I infer that the distinctions have been made somewhat arbitrarily, and, indeed, it is often difficult to make any, so that I ha\e thought it best to lump them together in Table III. The total numbers, however, were as follows : — „, I Percentages to ' °'^"'- total Malaria. Malarial Fever 358,079 87-6 Malarial cachexia 26,394 64 Enlargement of spleen ... ... 24,021 5'8 Total malaria* 408,494 — Dysentery 38,713 94 Dysentery was included in the return at Dr. Lorans' suggestion for the purpose of comparison — a \-ery useful one being obtained. 19. THE MEASUREMENT OF MALARIA IN MAURITIUS. — Having considered past statistics, we must now endeavour to obtain some idea of the present prevalence of the disease. (i). Recent Statis lies. —The figures for 1907 have not reached * This total is in excess of that given by Table III., because the latter deals with attendances during only thirty years, while the former goes back some years earlier. 5. Total. Malarial. Percentage, )77,532 — — 15,118 5,827 38-5 40-0 15-4 38-5 20,371 4,346 21-3 1,221 78 6-4 23,759 4,306 18-1 79,053 28,294 35-8 66 me in time for this report, but those for 1906 will suffice for the following" table : — Population (1906) Declared deaths (1906) Death rates per mille ... Adiiiissons (1906) Hospital deaths (1906) Hospital cases (1907) ... Dispensary cases (1907) We thus have many figures but, I fear, few results. The general fever mortality returns probabh' have a large margin of error, and it is difficult to say how far the hospital statistics apply to the entire population. We cannot sa)' how man\' patients attend hospital more than once, or how man}- ne\er attend at all. (2). Direct MctJiods for Meas?iri)ig the Ai/ioiaif of Mcxlaria in a Locality. — The principal point to be ascertained is, b}' section 10, the proportion of infected persons in the localit)', but this is not given, either b}- death rates or b}- attendance at hospital. The ideal wa}' to ascertain this ratio would be to search for the parasites in the blood of ever}- person in the localit}-. But the parasites often cannot be found, e\en when the\- must be present in considerable numbers. Kven when they are fairly- numerous the search for them in a single person ma}- occupy a skilled worker for half an hour or more, and may have to be repeated on several occasions. I doubt whether such a worker could examine properl}- the blood of a thousand people under two months' hard work. If he were to content himself with examining smaller numbers b}" what is called " random sampling," the statistical error might be considerable. Hence to estimate correctl}- the proportion of infected people throughout a large population like that of Mauritius would be a great task. There is, however, a much easier though less rigid method, \\hich consists in examining the [)eople for the enlargement of spleen w Inch occurs so frequently in cases of malaria. This can be done literall}' in a few seconds for each person. The people to be examined are lined up, and then made to pass the examiner one by one, while an assistant writes down the result ; or else the facts ma}- be ascertained b}- a rapid house to house \ isitaticMi. Thus a large 67 population can be dealt with in a much briefer time than would suffice for a thorough blood-examination. The method is a very old one, which was often practised in India. The best method, however, when practicable, is to combine the two, (3). The Eiidciiiic-bidex. — This useful term \\'as proposed by Stephens and Christophers to denote the proportion of persons with parasites in the blood. I suggest, however, that the term parasite- rate would be more suitable for this purpose ; that the term spleen- rate should be given to the proportion of people with enlarged spleen due to malaria ; and that the term endeniic-iudex should be reserved for both of the others together — or rather for the proportion ot infected persons ascertained b}' all methods. The combined methods were used by me in Greece in 1906. Out of 60 infected children whose blood and spleen were examined very carefully, 27, or 45 % had enlarged spleen, but parasites too few to be found; 21, or 35 % had both enlarged spleen and parasites numerous enough to be found ; and 12, or 20 % had parasites but no enlargement of the spleen. Now, if we had taken onU^ the parasite- rate or the spleen-rate we should have obtained too low an estimate. The combined method is especially useful, because early cases of malaria generally show numerous parasites but have little enlargement of the spleen ; while older cases, in m)' experience, show the converse. For practical purposes, the parasite-rate can be determined only (with much trouble) for small populations ; and for large ones, such as that of Mauritius, we must resort to the spleen-rate. But when we confine ourselves to the latter, we ought to add a certain percentage for cases in which, had we examined them, we would probably have found parasites, though they had no enlarged spleen. In the Greek cases, there were 12 such for 48 with enlarged spleens ; and though these cases were too few to give a ver\' reliable estimate, we may for the present accept the proportion for rough calculation. In practice also, we usually confine our examinations to children — say of under 16 }-ears of age. This is done for several reasons. Children are easily accessible in schools, or, for a small reward, in villages. Men are generally out at work, and women often object to the examination. But the most important reason is that adults have in many cases become partially immune (section 2). Thus if we 5 '^ 68 were to take people of each \'ear of age from one to a hundred, say a thousand of each age, we should find that the endemic-index rises from one to about ten years, and then falls ; until at pubert\- the bulk of people in a malarious locality show few signs of the disease, though the}' ma\' occasionall}' suffer from short attacks and are probabl}- realh' infected all the time. If, however, we had examined only the adults, we should ha\e discovered few objective s\'mptoms of malaria in them, and might ha\'e come to the conclusion that there was no malaria in the localit}". It, therefore, becomes apparent that we do not reall}- possess any ver\- practical method for determining the exact ratio of infected persons in a localit}-. We can find children with enlarged spleens or with numerous parasites ; but when partial immunit}- has banished these symptoms we are left in doubt. A person is " infected " as long as an}' parasites are left in him, but, unfortunatel}', we can never find definitel}' whether or no the}- have died out completel}-. All we can do is to take the children up to some arbitrary age, say i6, and then compare results. If none of them show signs of infection, the place is health}'. If some are infected, all we can state is that the endemic-index among so many children examined is such-and-such ; and we must e.xamine enough children to avoid statistical error. (4). Does Kala-Azar exist in Mauritius? — A most im{)ortant point remains to be studied. There are sexeral diseases, besides malaria, which cause enlargement of the spleen ; but onl}- one of these causes wide-spread enlargement, such as malaria does. This is the famous Indian disease kala-azar, which is produced by the minute parasites called Leishmania donovaui. Where it exists the spleen-test for malaria becomes obviously unreliable. Hitherto it has never been found in Mauritius. Unfortunatel}' during m}' sta}- there, no opportunity for searching for the parasites in the liver and spleen presented itself; but we examined several suspicious looking ulcers in vain. Owing to the large Indian immigration one would expect to find the disease in plent}' ; but, on the Nvhole, I infer that it is absent, or rare. I was sent b}' the Goverinnent of India to investigate kala-azar in Assam in 1898 : but neither in Mauritius nor in Greece did I observe cases altogether similar. The kala-azar patient has a depressed, anxious expression which is not often seen in malaria ; the liver is general I \' enlarged, as 69 well as the spleen ; there is generall)' a continued fever not cured by quinine ; and the patient almost invariabl)' dies. Now if all, or even a fraction, of the children in Mauritius with enlarged spleen have kala-azar the death-rate would be appalling. As a matter of fact, the children recover. The malady which causes enlargement of spleen among them, as in Greece, is a benign affection. It is also too frecjuently accompanied by the parasites of malaria, and too easily cured by quinine, to leave much doubt as to its nature. I gather then that the carrying agent of kala-azar is probably absent from Mauritius ; and that the spleen-rate will, therefore, give a reliable estimate of the endemic-index there. :. 20. THE SPLEEN-RATES OF CHILDREN IN MAURITIUS, AND OTHER DETAILS.— With these considerations in view, I advised Government, when I reached the Colony, to carry out a systematic spleen-census of the child population. This was done [a) by the Sanitary \\\ardcns, Drs. Castel, Keisler, Masson, and Milne, for the children in schools ; {U) by the Medical Officers of the Sugar Estates and Factories for the children belonging to them ; and by Dr. Milne, Major Fowler and myself for a certain number of children scattered in villages and hamlets. Owing to the large number of children examined, the work was arduous ; and my warm thanks are due to these gentlemen for their assistance, and also to Dr. Lorans and Dr. Bolton for their supervision of the statistics. So far, as I know, it is the largest spleen-census which has ever been taken. The details are given in Table IV. (i) Total Spleen-Rate. — At the census of 1901, out of 370,831 persons whose ages are recorded, there where 178,139 children of I 5 years and under, or 48-04 % of the total. In 1906 the total population is estimated by the Registrar General at 377,532; so that according to the same proportion there ought to have been 181,366 children in that year, or say 182,000 children of 15 years and under in 1907. The following table gives the results of the spleen-test ('carried out for the most part early in 1908). Children Children vvith Percentages, examined. enlarged spleen. Children on Estates 18,909 6,307 33-3 School Children 6,188 1,455 235 Miscellaneous 5,925 2,833 478 Totals ... 31,022 10,595 34.1 Thus, out of about 182,000 children in Mauritius, 31,022 were examined and 10,595 were found to have enlargement of the spleen ; or 34' I %. The statistical percentage of error according to the Poisson-Pearson formula (addendum 4) is only 0*693, ^^d may be neglected. Hence we may calculate that out of all the 182,000 children under 15 years of age in Mauritius, one-third probabl}- suffer from enlarged spleen. (2). Total Probable Endemic-Index. — But if we had examined the blood of all these children for the parasites of malaria (which was of course cjuite impossible in the time at our disposal) we should certainly have found a proportion of them containing the parasites, but not having enlargement of the spleen. According to the rough Greek estimate (section 19), these would number as many as a quarter of the spleen cases. Adding this proportion, we estimate that 13,244 children, or 427 % of the total, would probably have shown objective symptoms of malaria had we examined them all. Thus the endemic- index for children ofi5}-ears or under in Mauritius early in 1908 may be put at about 427 %, or over two-fifths. The children were examined largely before the great annual rise of malaria begins. Had we examined them later, the endemic index would certainly have been much larger. (3). Some Small Sources of Error. — It is likel\- that some of the children examined in the schools, on the estates, and elsewhere were the same children. I have not been able to ascertain the likely proportion in time for this re[X)rt. But, as we are here dealing with ratios, the matter will not seriously affect the general result. I have just been informed by Dr. ]^olton that few of the children of the indentured coolies on the estates attend the schools, and that in his opinion the overlapping cannot exceed 0-25 %, and will not therefore seriously alter the returns (annexure ]). Another point. I asked for children of 16 years and under to be examined. This was unfortunate, as the census deals only with five- }'earl\' groups. But tor the same reason, just given, the error caused may be practically neglected. Moreover, the exact ages of the poorer classes arc always very doubtful quantities. (4). Average Spleen. — I asked for records, not onl>' for enlarge- ment of the spleen, but for degree of enlargement — whether the enlargement was small, medium, or great. I have collected the 71 figures for 30,137 children examined. The enlargement is given as none in 19,711, or 65-4%; as small in 4,381, or I4'S%; medium in 3,479, or 11-5%; and great in 2,566, or 8*5%. As a rough estimate I take the " small," the " medium," and the " great " enlargements as being, respectively, three, six, and nine times the size of the normal spleen, which is taken at unity. Hence, adding together the children with no enlargement, three times the children with small enlargement, six times and nine times those with medium and great enlargements, and dividing by the total numbers examined, we obtain what I call the Az'erage Spleen. This w^orks out at 2" 54 for Mauritian children early in 1908, with small statistical error. See also Table IV, D. I do not think that this estimate has been attempted before. It is likely to give a more delicate index of the amount of malaria in a localit}' than the mere spleen rate ; but, unfortunately, medical men may differ as to the standards of small, medium, and large ; and the estimate is, therefore, not rigid. (5). Age and Sex Distribution. — I asked also for the ages and sexes of the children to be recorded. As a matter of fact, the ages generally have to be guessed by the examiner ; so that here again the estimate is far from rigid. In fact, on scrutinising the figures, I find so many elements of doubt that I have finally decided to omit the full age analysis from the table ot details — more especially as it would add immensely to the bulk of figures. But I have computed the totals for 4,025 children with enlarged spleen on the estates, and find that they were distributed according to age as below : — Age Children I 208 2 254 3 293 4 285 5 311 6 346 7 340 8 355 Age Children 9 247 10 328 II 192 12 255 13 172 14 185 15 153 16 97 Thus there were 1,351 children with enlarged spleen of five years and under; 1,648 of five to ten years ; and only 1,056 of ten to sixteen years. Out of the same number of children with enlarged spleen, 2,095 were males, and i ,930 were females — showing no marked difference. (6). Local Distribution. — The declared deaths from fe\'er in the various districts during the last eleven years, 1896- 1906, will be found in Table II, and the spleen rates and average spleen in Table IV. Flacq and Black River districts have the highest spleen rates and 72 average spleens ; and Plaines W'ilhems and Moka the least. The local prevalence of malaria \aries so greatly, even within a few- hundred }-ards, that it is quite impossible to examine all the details here. (7). TJie Imported Spleen Rate. — In ever\- localit\- an\-\\here near to a malarious area there must be a certain number of imported cases which will give a small spleen rate by themselves. This I call the imported spleen rate. As a rough rule it must tend to var}' inxerseh' as the square of the distance from the infectious area. On reference to Table W it will be seen that there are small spleen rates in Moka and Plaines W'ilhems ; and the remarks of the reporting Medical Ofificers show that these are mostly imported — although in both these districts there are a few infecting centres. Of course the imported spleen rate tends to be increased in places which are frequented from outside, as Curepipe ; but on the whole I think that, if the spleen rate of a localit\- is not higher than 5 %. there is likely to be little endemic malaria there. If only a few children are examined, so that the statistical error is large, the apparent rate may be much higher than this without giving proof of endemic malaria. For instance, in the schools of Moka the rate is 20"5 % according to Dr. Castel. This is large enough to suggest a malarial focus somewhere there ; but on the other hand the statistical error is nearl}- 8 %, so that the true spleen rate may be anything between 12 % and 28 %. Quite possibly the lower figure may be due onl\' to importation, especially in schools. (8), The Effect of Altitude. — That malaria decreases with increased altitude is known ever}-wherc, and has been frequenth' noted in Mauritius, where the conditions arc \-ery suitable for such a variation. Dr. Meldrum (lO; and the writers f)f the Annual Medical Reports and Reports of the Estates Hospitals have frequenth- shown that the death rate tends to diminish with altitude. Table I\', E gives the \ariation of the spleen rates according to altitude in a large number of children in Mauritius. Altitude must affect malaria chiefly by reduction of temperature — one degree Fahrenheit (0-56^ C.) for every 300 feet. Temperature affects it in many wa}-s. Cold is inimical to mosquitoes ; it retards the development of the parasites within them, and also, I think, in man ; and causes men to wear more clothing and to shut up their 7Z houses at night. On the other hand, large breeding places close at hand may neutralise all these factors — as. for instance, near the Clairfond marsh at Phoenix (1,400 feet). Hence, while the average infection rate diminishes with altitude, local rates must vary largely owing to other factors. (9). Relation hctzveoi tJie Spleen Rates and General Death Rates. — In Table IV, A, giving the spleen rates on estates, the death rates averaged for the two years ending June, 1907, are also given. But there is a large statistical error in these death rates, owing to the small numbers of deaths on many of the estates ; so that the relation between them and the spleen rates cannot be dealt with satisfactorily. In Table IV, F the same figures are given for whole districts, and are therefore more useful ; but I have been obliged to give the death rates for 1906, as those for 1907 (which should ha\e been shown in order to correspond with the spleen rates) have not yet reached me. There is evidently a marked, though not exact, relation — which I will not analyse without the figures for 1907. The separate death rates of estates are not an exact measure of the malaria in them, owing partly to statistical error. (10). The Parasites and the Fevers in Mauritius. — There is nothing of importance to our present purpose under this heading. The parasites can be found easih' in man and in P. eostalis, and do not differ in any respect from those observed all over the tropics. All species were seen by us. To determine which was most abundant was not necessary, and would have required many months' special work. Quartan abounds at Phoenix, and the malignant parasites are common. The clinical features of the disease have been excellently studied in many scientific papers, especialh' in those of the Societe Medicale ; and call for no remark here. Black water fever is common (addendum 2). 21. SUMMARY OF FACTS REGARDING THE AMOUNT OF MALARIA IN MAURITIUS.— A. The following figures give important averages during the seven years 1900-06 : — (i) The average population of Mauritius was 384,676. (2) The average total deaths per annum were 14,139. 74 The average annual total death rate per mille of population was 37-4. . • The average annual deaths reported as due to fever were 5,384 (doubtful). The average annual death rate/rr ]jiillc of population reported as due to fever was i4'o (doubtful). ' ' The a\erage reported fever deaths were 3 ro % of the average total deaths (doubtful). (3) The total admissions into the hospital for all causes averaged 18,761 a \-ear. The admissions into the hospitals for malarial diseases alone averaged 4,348 a year, or nearly one quarter (23-2 %) of the total admissions. The total deaths in hospital from all causes averaged 1,174 a year. 'I he deaths in hospital from malarial diseases alone averaged 84 a year, or 7-1 % of the total deaths. The ratio of deaths in hospital from malaria to admissions into hospital for that disease (case mortality) was r935 %. (4) The attendances of out-patients at all the hospitals and dispensaries for malaria alone averaged 13,464 a year since 1878. In 1907, alone, the total attendances for all causes were 79.053> 'in<^l for malaria alone were 28,294, or 35'8 % of the total. B. (i) There are about 182,000 children of fifteen years and under in Mauritius, (2) Out of 30.137 of these examined in all parts of ^Mauritius at the end of 1907 and the beginning of 1908, that is, before the middle of the malaria season, 19,71 1, or 65-4 ');), had no enlargement of the spleen ; 4,381, or 14-5 %, had small enlargement of the spleen ; 3.479- or 1 1 '5 /05 liad medium enlargement ; ^ 2.566, or 8-5 %, had great enlargement. From these data it may be computed roughly that the average spleen of Mauritian children is 2-54 times the normal size. {.D Out of 885 more children examined, 169 were found to have enlargement of the spleen. Thus, out of a total of 31,022 children examined, 10,595. or more than one-third (34-1 <;',;), had enlargement of the spleen. 75 Hence probably, out of tl« ,8.,CK« children in Mauritius, about 62,062 suffered from enlargement of the spleen. (4) If we suppose that children without enlargement of the spleen but with the parasites in the blood, numbered as many as a ' art ; o the spleen cases, then we must infer that at the begn.nmg :t:lrma,aria season 437 % of all the children in Maur,tu,s-that is about 77,714 children in all-were infected with malar.a Dr bL«. Medical Officer of the Immigration Dei«rtment, , , • ^„-t. the Estates in Mauritius Rs.650,000 a estimates that malaria costs the Instates ccnnnoin year in loss of labour, and the labourers themselves Rs. 1 50,000 n Z of wages, besides similar losses to the general community (annexure i). 76 PART III. PREVENTION OF MALARIA IN MAURITIUS. 22. BRIEF HISTORY OF THE PREVENTION OF MALARIA.— In sections 2 and ii it was made clear that malaria will not remain in a locality (i) unless the carrying agents (Anophelines) are numerous enough ; (2) unless there are enough infected persons to infect the carriers ; and (3) if the insects are prevented from biting human beings. There are thus three groups of pre\"entiv^e measures which may be employed by public authorities to reduce the disease, namely : — (i) Anopheline Reduction, (2) Case Reduction, (3) Isolation. The ancients knew that drainage reduces malaria ; and the statement has become a sanitary aphorism for centuries. Numbers of instances occurring in Italy and France are cited in text-books. The total disappearance of the disease from Britain and its decrease in Holland and other countries has been certainh- due in part to drainage of marshes, and in part to other causes — chiefly, I think, the frequent treatment of cases with cpiinine, and (?) the general use of glass windows which appears to ha\e followed the repeal of the window tax early last century. Thus all the preventive measures mentioned above were used — unconsciously. The Anophelines were reduced b}' drainage, the cases b\- quinine, and the remaining insects were largely prevented from feeding b\' the glass windows. But though drainage against malaria has been frequently" used, it has been more frequcntK- neglected. The Roman Campagna, for example, and many marshy settlements in the tropics have been allowed to remain malarious, in spite of the remed}' being known. This has been due to man}- causes — to the expense of drainage ; to the small [xilitical influence of the medical profession ; to faults- public education ; and, not least, to scepticism regarding the truth of the dogma, owing to absence of full explanation of it. When, however, the Anophelines were shown in 1897-99 ^'^ be the carriers of malaria, the reason wh}- drainage reduces the di.sease was clearly 77 revealed — it removes the stagnant weedy surface waters which breed the insects. In other words, drainage of the soil, as applied to malaria, merel}' means Anopheliiic reduction and nothing else. At the same time, as already stated in section i, the new knowledge greatly improved our methods. Instead of being forced to drain a whole area, we could now define exactly which waters were or were not dangerous, and could deal with the latter by several other means than by drainage — thus cheapening the whole process, and rendering it more exact and feasible. The precise details of the method were first laid down in 1899 (i) ; and were first put into practice in a complete manner at Ismailia and in Klang and Port Swettenham in the Federated Malay States, in all of which localities the disease was banished in a couple of years. Later the same method has been made the basis of the great sanitary work of the Americans in the Panama Canal Zone, and has been attempted with more or less energy elsewhere. Latterly Anopheline reduction has been merged in the wider and still more useful measure of general mosquito reductio7i^ especially at Ismailia, Panama, and Port Said. Meanwhile the second great anti-malaria measure, that of case reduction, had been originated by Koch and Celli as early as 1900. These observers felt doubt as to the possibility of mosquito reduction (since established), and urged that the best way of dealing with malaria would be to leave the mosquitoes alone, but to cure the human patients, from whom the insects become infected. Thus, though mosquitoes would continue to abound, they would find no parasites to carry. The classical example of the use of this method was Stephansort, in New Guinea, which was cleared of malaria by Koch in a few months. Much similar work has been done in German possessions and in Italy, and also among the troops in India. The third measure, that of isolatio)i or protection ftom bites oj mosquitoes, has been unconsciously in use for a long time. The ancient Egyptians and Romans used to emplo\' mosquito nets during sleep ; and I well remember being told, when I first went to India in 1881, that the\- would ward off malaria. Since 1898 I have always strongly advocated the use of them for that purpose. In America wire gauze screens for the windows and verandas of houses have long been employed ; and these were now strongl)' recommended, especially in Italy, as a protection against malaria. The experiment 78 of Low, Sambon, and Rees, who lived for two months of the malaria season in the Campagna in a mosquito-proof house without becoming infected, strengthened this recommendation. Though the experiment added nothing to our knowledge, and was not a strict test (since infection in two months is by no means a certainty anywhere), it was so widely advertised that wire-proofing was adopted in several places, notably in Lagos and Panama. Other precautions, such as boots, gloves, and veils, culicifuges (applications to the skin to keep off mosquitoes), and so on, were urged by some writers. Lastly, Stephens and Christophers emphasised the necessity for VaQseg-yegatioii of Europeans in the tropics, on the ground that, if they live far from native villages, they are less likely to be bitten b\' infected mosquitoes — an excellent suggestion. Last year I attempted to collect available information on the subject of anti-malaria campaigns in many countries. The task was difficult, owing to the inadequacy of most of the official and other reports on the subject ; but I published what facts I could ascertain (2). Work on a large scale in British possessions was first commenced in an admirable \\a\' at Lagos b\' Sir William MacGregor, who, however, was forced later by ill-health to leave the tropics — much to the loss of tropical sanitation. Other campaigns have been commenced in Sierra Leone, the Gold Coast, British Gambia, Hong Kong, many stations in India, Durban, Khartum, Candia, .St. Lucia, Havana, Mauritius (section 17), besides Italy, Greece, and French and German pcjssessions. The campaign in Sierra Leone was commenced in 1901 by Dr. Logan Taylor and myself, and was favourabl}- reported on at the time by Dr. C. W. Daniels ; but it is impossible to obtain adequate details of what has happened there since we left, and the statistics show little improvement. A campaign at Mian Mir, in India, was a failure, owing to insufficient expenditure and other reasons which I analysed in a paper published in 1904 (4). The campaigns in the other localities mentioned have been more or less successful, so far as I can ascertain. Last year I urged that the authorities would do well to collect information on the subject in the form of special malaria reports ; and, owing to the request of Colonel Seely, C.B., M.P., the Right Honourable the Secretary of State for the Colonies was good enough 79 to order such reports for his department. These have recently been published by the Advisory Committee of the Colonial Office for the Tropical Diseases Research Fund (17). On studying them I find that they give little evidence of a thorough and practical policy against malaria in most of the colonies. Strangely enough, all accounts of two of the best campaigns, namely, those at Klang and Port Swettenham, in the Federated Malay States, are omitted ; while the campaign at Hong Kong is repre- sented only by a single inadequate extract from a medical report. Similar extracts, often consisting of only a few lines, constitute all that is given for many colonies. One medical officer (Perak) remarks that ' with our heavy rainfall the banishment of puddles and other suitable places for the breeding of mosquitoes is practicall}^ impossible " — ignoring the fact that this is just what has been done in the neighbouring State of Selangor. Free quinine, lectures on elementar}- hygiene, and covering of water barrels seem to constitute all that has been attempted in many localities. In several of the West Indian Islands, it is admitted that nothing at all has even been attempted. Statistics, where they are vouchsafed at all, are generally quite inadequate ; and I have searched the reports in vain for any account of so simple and easy a measure as a spleen census. Suitable anti-malarial organisations have not really been constituted. The reports generally suggest the idea that the colonies have still much to learn regarding the prevention of malaria. There is much talk at present of research and instruction on tropical diseases ; but it would seem that, though the cause and the mode of prevention of the most widespread and important of tropical diseases — one that often causes as much sickness as all the other diseases in the tropics put together — have already been discovered and taught, yet that little or no action is to follow the acquisition of that knowledge. Nevertheless good work has been done in some of the colonies. I note especiall}- Southern Nigeria (Lagos), where Dr, Strachan, the first Principal Medical Ofificer in West Africa to attempt malaria reduction by modern methods, and the Director of Public Works have continued the efforts of Sir William MacGregor by drainage, quinine, wire gauze, public instruction, and other methods. The former admits a great improvement in the health of the European oiificials. In Ce}-lon quinine has been largely issued at the cost of 8o Rs. 73, 299 during 1906, not including wages of distributors. At Bathurst (Gambia), where the work was started in 1901 b\' m\' junior, Dr. Button, according to m}' instructions, a malaria gang of ten men has been appointed for the purpose of " minor works," and the health of the European officials has improved ; but it appears that the larger swamps cannot be touched (?). In the island of Samarai (Papua) Anophelines are stated to have been entireh' exterminated by the drainage of a swamjj. The good work in Mauritius has alread\- been touched upon (section 17). I will now proceed to a description of the leading examples of malaria reduction by modern methods, taken from m)- publication alread}- referred to (2). 23. THE PREVENTION OF MALARIA IN ISMAILIA, THE FEDERATED MALAY STATES, HONG KONG, AND THE PANAMA CANAL ZONE, ETC.— (ij. Ismailia. — The town of Ismailia was founded b\- the great Ferdinand de Lesseps in 1862 at a little distance from the middle point of the Suez Canal and close to the salt lake, Timsa. Though built in the midst of the desert, which surrounds it everywhere with its ridges of white sand like the undulations of a vast snowfield, it has nex'ertheless now grown to contain about 8,000 inhabitants, most of whom are employees of the Suez Canal Compan}'. Supplied with fresh water by means of a canal from the Nile, it possesses man}' good houses, gardens, and well- appointed streets, kept in admirable order by the officials of the compan}' under the able and energetic President, Prince Auguste d'Arenberg, who himself resides here for man}- months every year. Immediately after the construction of the fresh water canal in 1877 malaria appeared for the first time in the town, which had been previously noted for its salubrit}'. The cases graduall}' increased in number until in 1886 almost all the inhabitants suffered from fever. In 1 90 1 the President, having recognised the new discoveries, deter- mined to employ them against this troublesome epidemic, and commenced h}' sending a member of his highly competent medical staff, Dr. A. Pressat, to Italy to study the subject. Early next year, however, shortly after the commencement of the operations at Freetown, he invited me to go Ismailia to advise upon the best means of attacking the disease. I arrived there in September, 1902, with Sir William MacGregor, who did me the honour to accompany me, and with Dr. Pressat on his return from Italy.* On our arrival we found all the officials of the company keenly alive to the importance of the work. They had alread}' detected the Anophelines in the town, had urged the general employment of mosquito nets, and had commenced an active quinine prophylaxis. On the other hand, the town was still swarming with mosquitoes. Even in the house of the President, where we were lodged, there were multitudes of Culex, which we showed were being bred in the well- constructed cesspit under the house ; while abundance of Anophelines were found in the houses of the employees, and were evidently carrying the disease everywhere in spite of the mosquito nets and the segregation of the Europeans. I felt, therefore, that here, as in other places where I had studied the subject, we should have to introduce the radical method of mosquito reduction if we wished for complete results, and I reported strongly in favour of this course. As Dr. Pressat has said, we formed " the conviction that weshould establish for Ismailia a plan of campaign sensibly different from that which we had seen followed in Italy, where the campaign against mosquitoes occupied only a secondary rank — so that this destruction appeared to us to be the capital article of our programme " (p. I30).t We found the larvae of the Anophelines at once in various collections of water, principally in some small brackish marshes in the sand and some waters of irrigation, but happily not in the main fresh water canal, where small fish destroyed them. The campaign, conducted with intelligence and energy, presented no great difficulty. The marshes were filled up with sand, the irrigation channels were deepened or treated with oil, while the cesspits were soon rendered uninhabitable for the larva; of Culex. As Dr. Pressat has said,; he was able to effect the preliminary work with a "mosquito brigade" of only four men, " qui a tout fait." Although hundreds of men were employed later for large permanent works, this was only after the mosquitoes had already disappeared " grace a notre brigade de quatre hommes." I may perhaps be pardoned for dwelling on this fact because it fully * Ross: Report on Malaria at Ismailia and Suez. Liverpool School of Tropical Medicine, Memoir IX., 1903. t Pressat : Le Paludisme et les Moustiques. Masson at Cie., Paris, 1905. t Pressat: Prophylaxie du Paludisme dans I'Isthme de Suez. La Presse MMcale, 30 Juillet, 1904. 6 82 justifies the advice which I had given more than three years previously, but which had been met everywhere with scepticism. The results were most striking. It should be remembered that, as nearly all the inhabitants of Ismailia were employees of the Suez Canal Compan}-, and as no other fever was prevalent in the town, exact statistics for many \-ears had been possible. I give the following approximate figures from Dr. Pressat's works from the time when malaria first appeared in 1S77 to 1905 : — Ware Cases of w^,- Cases of ,. Caees of ^^''''- Malam. ^^'^^^- Malaria. ^ *=^''^- Malaria. 1877 300 1887 1,800 1897 2,089 1878 400 1888 1,400 1898 1.545 1879 500 1889 1,450 1899 1,784 1880 400 1890 1,900 1900 2.284 1881 450 1891 2,500 1901 1,990 1882 480 1892 2,050 1902 1,551 1883 550 1893 1.750 1903 214 1884 900 1894 1,100 1904 90 1885 2,000 1895 1,350 1905 37 1886 2,300 1896 1,150 For more exact figures I must refer to Dr. Pressat's works. Since 1904 nearly all the cases ha\e been relapses among persons previous!}- infected, and last \ear the company officially reported that '' toute trace de paludisme a disparu d'Ismailia." Of course, the treatment of old cases has constantly proceeded parallel to the anti-mosquito campaign. But the fortunate inhabitants have been relieved not onh' of malaria, but of the constant annoyance caused b>- the insects. In 1902 we were constantly being bitten in the hou.ses. Now, as man\- visitors to Ismailia have testified,* one can sleep there ^\ ithout nets. This does not imply that the insects are absolutely unknown in the town, but only that their numbers have been ver\- greatl\- reduced. Absolute extirpation is scarcely possible without bonification over a very wide area, but, as mathematically shown, reduction to a small percentage is much more feasible, and there are evident logical reasons for supposing that the amount of an insect-borne disease must ultimatel}' var\-, ccetcris paribus^ as the square of the number of the insects. The cost of the work has been officially reportedf as being * Boyce : The Anti-m.ilaria Measures at Ismailia. Liverpool School of Tropical Medicine. 1904. t Official Report of the Compat^nie Universelle du Canal M.-iritime de Sv\ez. .Suppression du Paludisme a Ismailia, 1906. 83 about 50,000 frs. for the original drainage and filling up of the pools, with an annual expenditure of 18,300 frs. for the mosquito brigade, oil, maintenance, &c. This amounts to an initial expenditure of about 6-25 frs. and an annual expenditure of about 2-3 frs. per head of population— a small price to pay for the benefits given. It has been said by the opponents of mosquito reduction that the success at Ismailia was not real, but merely consisted in the statistical transfer of cases from the heading of malaria to that of other fevers consequent on better diagnosis. This is untrue, as there is no other fever there. It has also been said that the success was due to the exceptionally easy conditions at Ismailia. True, the conditions are not so difficult as in places like Panama and Sierra Leone, but I have seen many areas where they were quite as easy as in Ismailia, but where nothing whatever has been done. The success at Ismailia is absolutely unquestionable. It is due chiefly to mosquito reduction and also largely to cinchonisation. We owe it entirely to the intelligence and capacity of Prince d'Arenberg and his excellent staff. (2). Federated Malay 5/^/^.^.— Commenced even before the cam- paign at Ismailia, as ably conducted and almost as decisive, the work at Klang and Port Swettenham, in the Federated Mala)- States, is an equally distinguished example of the radical method of malaria reduction. Klang is a town of 3,576 inhabitants (in 1901), situated on the banks of the river of the same name, in the State of Selangor, on a flat, swampy area lying between the river and a semicircle of low hills. In September, 1901, as the navigation of the river of Klang presented difficulties, a new port called Port Swettenham was opened five miles down the river from Klang on an area reclaimed from mangrove swamp. The population of the two settlements together was about 4,000 in 1903, while that scattered through the surrounding district was about 14,000. The rainfall averages about 100 inches (3 metres) a year. The full history of the campaigns in these two towns is given in the excellent papers by Dr. M. Watson, the district surgeon, and Mr. E. A. O. Travers,* the state surgeon. In the latter part of * Travers: An Account of Anti-malaria Work . . . in Selangor. Journal of Tropical J/«a??V/«£, Sept. 15th, 1903. u AT 1 • f T.'io„„ Watson • The Effect of Drainage and other Measures on the Malaria of Klang, Federated Malay States. Joinnal of Tropical Medicine, Nov. i6th and Dec. 1st, 1903. Ibid. : Second Report. Journal of Tropical Medicine, k^xAiii, i^^S- Travers and Watson : A Further Report. Journal of Tropical Medicine, July 2nd, 1906. 6a 84 ipoi malaria became ven- serious in both towns, and, according to Dr. Watson, perhaps not more than three houses in the whole of Klang escaped infection, while the workmen at Port Swettenham began to leave the place. Dr. Watson immediately set himself to collect statistics, to observe the local Anophelines, and to take the pve- liminary steps for the campaign. Supported by Mr. Travers and the Sanitar}' Board and b}' the intelligence and liberalit}- of the Government, he soon obtained realisation of the recommendations of himself and his colleagues made on the lines laid down b}- me (I). At Klang work was commenced in 1901 b}- extensive clearing of undergrowth, followed b}- drainage in the next year, llie swamps in the town were rapidh- filled in, and a contour drain to intercept the inflow from the surrounding hills was cut. At Port Swettenham forest and mangrove swamp were felled, and a complete drainage scheme, prepared by the state engineer, w^as carried out. In both tow ns, pending completion of the drainage, mosquito brigades were appointed ; and their emplo\-ment was extended subsequently under the name of " town gardeners." When the epidemic had already begun to subside, wire gauze was supp^lied to many of the houses, and an active quinine distribution was commenced. All the measures have been well maintained since then. As regards cost, Mr. Travers and Dr. Watson state that at Klang it amounted at the end of 1905 to a total of ^^3,100, with an annual expenditure of ^210 for town gardeners and of ^60 for clearing drains. For this money 332 acres (134 hectares) have been dealt with, including virgin jungle, dense secondary- growth, and swamjx At Port Swettenham the total cost has been ;.^7,000 to the end of 1905, with an annual upkeep of x^i40. For this no acres (45 hectares) of mangrove swamp were drained, and a considerable area has been levelled, parth- to provide building sites. The cost per head of population has therefore amounted to about ;^i. 4s. up to the end of 1905 — a very small charge considering the heav}^ rainfall and the dense vegetation of the countr}-. These towns did not possess the exact statistics of Ismailia for a long period previous to the campaign. Great credit is therefore due to Dr. Watson for the care and skill with which he has determined the results of his 8'5 measures. The following table is compiled from the figures given by him : — RESULTS OK .H.ANTI-MALAKIA CA^..AIO^■ IN KLANO ANU POKT SWKTTENHAM. (From the/..-../ ./ Tr.pna! Medccine, July and, .906, by Mr. Travers ar.d Dr. Watson.) Population of Kl.ng and I'or. Swe.tenham abou, 4.000 in .90. and no« largely increLid. Dis.ric, popl.ion .4,000 in .,o,. An.i-.nalaria ca„,pa,g„ co.mence.Monly in Klang and Port Swettenham) in 1902. ..-Cases of Malaria a.Unittai to Klang Hospital fro.n tlu Tu. Ton., co.npared untk those admitted from District. Years ^9°. 19- ^903 -904 ^505 610 199 69 32 23 ^''''''' 197 204 150 266 353 District ■^^' 2 -Deaths in Klang and Port Sivettenham. xQoo i9°i '90^ '903 1904 '905 ,. '"^^ - •• 259 368 59 46 48 45 '7'' ;. 215 214 85 69 74 68 Other diseases ■^■^^ ^.-Deaths registered in District, excluding Totvns. Years 1900 ^90^ ^9°^ 1903 1904 1905 Klang. 173 "'.. ••• ••• ^ Port Swettenham. 87 1 District, 298 101 November and December, 119 1 1905. 76 247 59 ,, ■" 173 266 227 230 286 351 '" ,. ■■■ ■■■ m 150 176 198 204 271 Other diseases ... 135 J-OU ^—Infected Children in Towns and District. November and December, 1904. Cliildren examined Children infected Children examined Children infected 5 -Sick Certijicates and Sick Learc granted to Uorernment Employees. (Numbering 176 in 1901 and 281 m 1904.) 1901 iyo2 1903 1904 1905 Y«^--^ - - 236 40 23 14 4 C^^^'^^^^f ■■■ 1026 198 73 71 30 Days of leave ••■ ■"' To these figures Dr. Watson adds that so great has been the reduction of the tnalaria that he has lost a large part of h,s pnvate pra tice as District Medical Officer. Regarding the ,-educt,on o '." quitoes, he remarks:-- A definite improvement ,n the health of Kla," was evident when only the swamps nearest to the main groups ^f h otises had been dealt with, and while other swamps w.thin the 1' ere still untouched. The mosquitoes from the.se did not ; a,, to travel a„>- distance, and there has been no evidence of 86 dangerous immigration of Anophelines from the extensive breeding places which, until the middle of 1904, existed just outside the town boundary, and some of which still remain. Yet the species breeding in these swamps were identical with those breeding within the town " The objection raised against the campaign at Ismailia — namely, that it possesses a dry soil and climate — cannot be raised against the well-conducted campaign of the Federated Malay States, and the world owes a debt of gratitude to the Government of these States, to Mr. Travers, and especialh- to Dr. Watson, for the fine example which they have set. (3). Hong Ko7ig. — One of the earliest and best of the campaigns in British territor}\ The city of Victoria, usuall}- called Hong Kong, runs for nearh' fi\-e miles along the north of the island of that name at the mouth of the Canton river in South-east China. The island, II miles long and from two to five miles broad, consists of a broken ridge of hills, rising to nearh' 2,000 feet, and the cit\- is built on a hill sloping down to the water, some of the terraces and houses being 500 feet above sea-level. There is also a large residential district on the mountains reached by a cable tramwa}'. The soil is granitic. All along the face of the hill on which Victoria is built there are beds of streams, known as " nullas," which used to swarm with anopheline larvai. The population of the colon}' was 377,850 in 1905, of which 10,835 were whites (nearly half belonging to the British Army and Navy). The rainfall is from 70 to So inches a }'ear. Malaria has been alwax's \cr\' prc\'alcnt here, and I remember that in iSSi the colons- was cited as an example of the telluric miasma due to deca^'ing granite. The first researches on the new lines were commenced as early as May, 1901, b\' Dr. J. C. Thomson,* who undertook an exhaustive study of the mosquitoes and their breeding-places. He examined over 32,000 specimens, of which he found about 4 per cent, to be Anophelines, and in November advised an active anti-malaria campaign by drainage, clearing of jungle, " training " of the nullas, the use of wire gauze, oiling pools, and quinine prophylaxis. As seen by his excellent papers,t his recommendations were not of a general * Thomson : The Distribution of Anopheles .nnd Ciilex nt Tlont,' Kony;. Brit. Med. Jour. 1901, vol. i., pp. 749 and 1379. t Ibid.: Malaria Prevention in Floni; Koni;. LJtiicial Keiiorl, containing many letters, 1 900- 1 903. 87 nature, but were particular, practical, and exact. These recommenda- tions were rapidly acted upon by the Government. Since 1901 all the nullas or water-courses within and near the city were " trained " — that is, rendered so smooth and even that the xA.nophelines could no longer breed in them ; and much similar work was done wherever most needed elsewhere by training water-courses, buying up rice fields, and so on. The details of the campaign are so numerous that it is impossible to give them here. They will be found in the publications given in the bibliography and in a good paper by Mr. J. M. Young,* who took part in the early stages of the work. The results are given in the annual sanitary reports of the colony and in a recent address b\- the medical officer of health, Dr. W. Francis Clark. t Dr. Thomson informs me that before estimating them it is necessary to remember that malaria can never become extinct in Hong Kong owing to the fact that some 3,000 to 4,000 natives come and go from and to the country districts every day, and that a number of these will remain infected in spite of all local measures. Neverthe- less the figures show a rapid diminution both in the admission and m the death-rates. Malaria Statistics of Two Large IIosi-itals. Years Admissions Deaths 1897 1898 1,021 865 197 126 1899 780 63 1900 I 90 I 1,220 1,294 163 132 1002 752 128 1903 568 63 1904 1905 433 419 58 54 Admission Kate of POITC E FOR Malaria. .. 1896 32 1897 iSoS 25 19 Deaths ki 1899 31 ;0M M 1900 I 90 I 42 44 [alaria. 1902 19 1903 18 1904 1905 11 12 1S96 239,419 1897 1S9S 1899 1900 I90I 1902 1803 1904 1905 — 377,850 533 554 530 546 555 574 425 300 301 285 '*'' 1 290 302 280 218 242 281 189 152 90 87 Years Admission, ' Years Population Total deaths Deaths in city (Chinese ) only) ... )""' The official sanitar\' reports give similar figures. The improve- ments have, of course, varied mtich in difi'erent localities. Thus in 1900 the western end of Bonham-road used to be one of the worst * Young: The Prevention of Malaria at Hong Kong. Brit. Med. Jour., 1901, vol. ii., P.6S3. t Clark: An Address on ihe Prevenli.m of Malaria in Hong kong. X(.ronha .V Co., Hong Kong, 1906. 88 districts. Now in 1905 it is reported not to have sent a single case to the Government Civil Hospital.* With regard to cost, Dr. Clark reports that up to the end of 1905 the Government had expended about iJ"5,ooo on anti-malaria measures, and estimates that £6,500 would be spent by the end of 1906 — a small amount to pa}' for the good that has been done. The campaign in such a thickly populated district must be difficult. A larger expenditure would probably have produced still more marked results, and it would have been useful to estimate the endemic-index in various parts of the area. I am much indebted to Dr. Thomson and also to Mr. J. Bell for the detailed information which they have been so kind as to send me, but which I have no space to give more full}'. (4). Panama Canal Zo7ie. — As is well known, the attempt of the French to cut the canal through the isthmus was foiled principally b}^ }'ellow fever and malaria, and I was told that their effort had cost quite 50,000 lives. The Americans took possession of the works early in 1904, at a time when the mode of propagation and of prevention of both diseases was well known, and the}' wisely determined to commence their labours with sanitation. Colonel Gorgas, as.sisted by a capable and enthusiastic staff, was put in charge, and attacked the work with knowledge and energ}'. 1 visited the place at his invitation in the autumn of 1904, and was a witness of the skill shown in his dispositions. The countr}' is one of the worst to deal with which I ha\e ever seen. Hill}', with a great rainfall, a loose, crunibling soil, a luxuriant vegetation, and innumer- able small marshes and pools, it was e\identl}' the ver}' stronghold of malaria. Step by step, with the aid of numerous experts and hundreds of workmen, the Americans cleared the forests, drained the pools, and banished the Stegoniyia. The details and the results will be found in the monthly and annual reports of the workt and in a recent address by Colonel Gorgas. J Tut briefl}-, the results * Reports on the Health and Sanitary Condition of the Colony of Hong Kong, 1900-1905, p. 54. t Reports of the Department of Health of the Isthmian Canal Commission, Monthly and Annual. Government Printing Office, Washington. X Gorgas : Sanitation in the Canal Zone, /oiinia/ of the Aineihaii Medical Asso- liaiion, July 6th, 1907. 89 are that in 1906, amongst 5,000 white American employees, the total death rate was only 7 per mille, and of this only 3-8 per mille were due to disease. Last April the daily sick rate of the total force of about 40,000 people was only 17 per mille. Colonel Gorgas says :— " Among 6,000 Americans in the employ of the Commission, including some 1,200 American women and children, the families of these employees, we have but little sickness of an>' kind, and their general appearance is fully as vigorous and robust as that of the same number of people in the United States." These published statements are full)- borne out by private communications from individuals living there. Colonel Gorgas adds :-" I think the sanitarian can now show that any population coming into the tropics can protect itself against these two diseases (yellow fever and malaria) by measures that are both simple and inexpensive . . . . ; and that again the centres of wealth, civilisation, and population will be in the tropics as they were in the dawn of man's history." Sir Frederick Treves, who visited Panama last Februar>-, read an interesting paper on preventive medicine there, before the Royal Society of Medicine, Epidemiological Section, on the 22nd May, 1908 (18). Regarding malaria, he said :-" The crusade against malaria has been even more elaborate. Every new arrival on the isthmus is handed a printed circular explaining the cause of malaria and the means of its prevention, and advising the constant use of quinine in do.ses of at least 3 gr- a day. Quinine is placed on the table m the dining rooms and boarding camps, and large quantities of the drug are distributed broadcast. In the month of September, 1905, for example, 675,000 gr. were dispensed, mostly for prophylactic purposes. A large number of men are kept constantly employed in cutting down the dense tropical undergrowth, in mowing ov burning the grass, in making and lining ditches, in filling in swamps, and in oiling the surface of any pool or puddle in which mosquitoes might breed. Others are employed to inspect water tanks and barrels, to destroy such as can be dispensed with, and to screen such as are retained As an example of the work of the anopheles brigade it may be noted that in 1906, in Colon alone, the surface oiled amounted to 330,000 square feet. New ditches were cut to the extent of 200,000 lineal feet. Of these ditches, 20,000 feet were stoned or cemented. Two million lineal feet of old ditches were cleared. 90 graded, stoned, or filled in. The area of brush and grass cleared amounted to 21,000,000 square }-ards. Never has a crusade been carried out with such completeness, for never has a chief sanitar\' officer had so free a hand. It is needless to point out that the mere oiling of pools docs not constitute the sole proph3-lactic measure against malaria. In a well-to-do town in the tropics it ma}' be supposed that the land has been thoroughl}' drained and every suspected area oiled, but there are still man}' varieties of vegetation which afford a breeding place for mosquitoes ; as instances ma}' be cited pines and such a palm as the traveller's palm. It ma}' be sure that the pine grower will not sacrifice his harvest in the public interest, nor will the wealthy resident allow the palms, which are the glor}' of his garden, to be cut down. It is much to be hoped that a list will be forthcoming of garden and other plants in which mosquitoes breed. On the Canal Zone no such list was needed. The place denounced was swept bare." Colonel Macpherson, C.M.G., R.A.M.C., who also has recenth' visited Panama, informs me that the total cost of the sanitary measure there is 2,000,000 dollars per annum, or about one-tenth of the total annual expenditure on the canal work. This includes the whole medical expenditure. (5). Aiiti-Stcgomyia Campaign at Port Said. — Although Stegoniyia does not carr\' malaria, it is such a pest in the tropics that it (Uight to be attacked if possible. It has been almost completel}' banished fi'om Port Said b}- a campaign carried out under the orders of the Gcnernor, Moulieb Pasha, and the recent l)ircctt)r of the Kg}'ptian Sanitar}' Department, Sir Horace Pinching, 1)\- ni\- brother, \\. H. Ross. Port Said has a crowded population of 56,000 people of man\- nationalities; and the insects used to breed chiefi}" in cellars and cesspits under the houses, the rainfall being small. The cost of removing them amounts to sixpence per annum per head of i)o])u- lation. Dengue and other fexers liaxe sinuiltaneousl}- disappeared from the town, and also from Ismailia, wlierc simiku' work has been done (19, 20). (6). Italian and other Caiupaigi/s. — I do not propose to describe these, as the coiulilions under whicli the\- were effected are not \-er}' similar to those in the tropics. In Ital\' there is a white population, close to large cities and with plent\- oi medical attendance at hand, s« ,o that the measures said to be most suitable have been ch.efly quinine prophylaxis and isolation^ In Greece the campaign tes only just begin, and in many other places few statistics are available. 34 PRELIMINARY CONSIDERATIONS REGARDING PRE- VENTION.-At the beginning of section 2., the various measures for public malaria reduction were given as («) mosquito reduction, if) case eduction, and (.) isolation. It is obvious that any one of these, ,f completeh- carried out, must result in the complete suppression of endemic malaria in any locality. Unfortunately, however, pubhc funds are limited, and the question arises, which of these measures will give the best results for the least expenditure ? The subject is a favourite one for discussion at medical con- ferences but the conclusions are not alwa>-s useful, owing to frequent inexperience in some of the speakers. Yet during the last ten year.s we have acquired considerable experience regarding the utility and feasibility of the various measures ; and, I think, the men who have actually dune the work-Gorgas, Pressat, Watson, and others-are agreed as to which are best. The answer to the question is, of course, much modified bj- local conditions. Of what race and degree of intelligence are the inhabi- tants ' Are we dealing with cultivated or uncultivated rural areas; with villages, towns, or cities? What is the rainfall' Does it fall mostly in summer or winter? Is there a sharp winter, or an and summer? Is the ground flat, or gently or abruptly .sloped ? Is ,t pervious or impervious, high or low, forested or bare? What are the crops, and how are they watered ' Are the people wealthy or poor How are they housed? What are the methods of communication Is there sufficient medical attendance:' Is registration of death good . Is the form of government arbitraiy, political, or practical? Has the medical profession any influence in it? And, above all, what is the state of the public purse? It is advisable to begin with some general (,) ' F,<,;„ of govermnent.-W should be understood at once that with certain forms of government real malaria reduction is simply out of the question. I refer not only to the uncivilises and minor " free" elected government. livery sanitarian recognises 92 at a glance the unfortunate territories ruled b}- such. The ill-made roads and gutters ; the crumbling walls ; the dirty unpainted houses, built anywhere and an}-how ; the foul }'ards, with noisome latrines, and littered with rubbish ; the leaking water-pipes ; the choked street drains, conxerted into cesspits ; the idle police ; the scanty workers, and the numerous officers. We can see at once that the funds which should be devoted to making the place tid}', clean, and health)- for the good of the public are being diverted to other uses. The public councils and offices are the prey of persons who gain their position b\' ad\ertisement, and who ktiow and care nothing about management ; and order, discipline, and science are unknown, while the councillors pretend to quarrel o\'er childish political issues which have long ceased to interest educated persons. To appeal to such to carr}- out a sustained anti-malaria policy is quite futile. No such bod\-, so far as I know, has ever yet attempted this task. As Sir Frederick Treves points out, the great work at Panama is due simpl\- to the strong scientific form of government in force there. If, then, an\' real sanitar)' work is t(j be expected, the form of government must be such that defaulting local authorities can be forced to attend to the duties for which the\- were appointed — foremost among which is sanitation. (2). TJie first [>reliiiii}iary to success. — Granted then that wc have to deal with a rational and practical form of government, the first step for that government to take is to decide definitely whether or no it really intends to attack the disease. Sanitation is a form of war. It reciuires mone\', discipline, organisation, and tliDUght. A scientific gox'ernment rccngnises that widesjircad disease is a great bar to prosperit}-, and can be fought onh' by concerted measures, which are mostl\- be\-ond the i:)owers of the individual citizen, and must be, at least, directed b\- authoritw On the other hand, it is the guardian of the public purse, and must refuse to sanction expenditure which ma}- lead to no result. It must therefore begin b\' obtaining an estimate of the amount of mischief produced by the disease, and of the cost of reducing it thoroughU'. Obvious as this principle is, it is fre(iuentl}', if n(jt generally, neglected ; no real efforts are made to measure the disease (as described in section 19) ; and the efforts made to reduce it are often merc!\- nominal, and consist only of popular lectures on mosquitoes and rules about i)lacing wire gauze on water-butts. (3). Necessity for repeated measurements oj uialan'a. — Not onh- 93 should the disease be measured to bec^in with, but the process should be repeated regularly in order to ascertain whether the preventive measures, whatever they are, are producing the desired effect. With organisation, the spleen test can be applied once, if not twice, a j^ear without serious difficult}-. The authorities can thus obtain data to justify their expenditure, and can also ascertain which localities most require it. Without such methodical estimates, the anti-malaria campaign may show no tangible results, even if they exist, and will probably be abandoned before long. (4). Limits of expenditure on anti-uialaria -work. — Theoretically it would be justifiable to spend as much mone}- for the prevention of malaria as the disease costs the communit}*. It is a great source of waste of money {a) by deaths and reduction of population ; {b)hY loss of manual labour in plantations, factories, farms, &c. ; (c) by sickness among government labourers and officers ; {a) b}' in\aHding and deaths among higher officials and soldiers fannexure i). Practically, however, governments must be limited, not only by their own revenues, but by that part allotted to the medical and sanitary budget. Perhaps the best estimate under this head may be formed b)' comparing the total amount of sickness due to malaria with that due to all causes — generally a large percentage. It may be argued, for instance, that, if malaria causes one-third the total sickness, then one-third the medical budget should be expended on its prevention. This would be scarcel}' fair, as other diseases often produce a greater mortality though less sickness ; but the argument helps to put the matter in a clearer light. In many countries, while the total expenditure on medical staff, hospitals, dispensaries, conservanc}-, sewerage, water- supply, quarantine, registration, (Sec, is great, that on the prevention of malaria, which may cause nearly half the total sickness, may be almost nothing. Yet it might be urged that if malaria could be banished, the people would really receive more benefit than by most of the other sources of expenditure put together. Both Dr. Meldrum and Mr. Chad wick have touched upon this point. (5). Ail Pleasures against malaria nuist be continued indefinitely. — It is well that this should be understood clearly to begin with. The work, if it is to be anything but a futilit}', will be a permanent burden upon the estimates. It might be possible, I think, to extirpate the disease entirely from an island like Mauritius — but this 94 could be done onh' at greater cost than is likely to be faced at present ; and even after that, \er\' stringent quarantine measures would have to be taken to exclude infected immigrants. But with gcjod organisation the disease can, I consider, be so largeK' reduced that man}' items ot the cost of the campaign will also ultimately diminish — j^erhaps very largely. That is all that can be promised. At the same time the cost to Government ought to be recouped b}- saving to the public, and consequent addition to re\enue. (6). Sou/c Icgislatio)! and discipline necessary. — Although much anti-malaria work can be done without troubling the public, yet, if it is to be done with econom}-, the public must be called upon to take their share of the burden as well as of the ad\-antages. Certain petty laws and regulations are necessar\-, and the public must comph- with them. One of the most serious difficulties in the wa}' of all sanitar}- improxement e\'er\-where lies in the inadequac\- of punishment often given by magistrates for sanitar\- contraventions. Fines are too small to be deterrent ; endless petitions are allowed ; and the time of the sanitar}' departments, which should be spent on useful work, is used up in attending courts and writing up cases — a simple -waste of public funds. This is not freedom but licence. It is a \er}- low form of civilisation in which individuals are allowed to abuse the freedom which civilisation has given them by poisoning or infecting their neighbours. If those who make and administer the laws were called upon to sit by the side of dying patients, as medical men too often are, and to watch the effects of the bereavements that follow, the}- would not so often treat these serious offences as jests or as pett}- lailings. I'he success of the work at Panama lias been largel}' due to the great powers given to the health department, and to the .stringent discipline exerted ; and the public themselves have become thankful for this wise severit}-. Sanitary discipline is like the discipline of the sick room, against which onl}- the most foolish |)atient rebels — to his own sorrow. (7). Special organisafiivi adinsable. — As alread}- frequentl}- stated, in some countries malaria causes nearly as much sickness as all the other diseases put together. The prevention of it therefore deserves very serious and special attention from the Government. There must be a special working organisation ; and as a rule it should be placed under an officer of the Health Department, purposely selected for his 95 knowledge of the subject and his capacity for scientific administration. He should be ordered to prepare every year a special malaria report, detailing the annual measurements of malaria, and the practical work- done by his department. So far as I can see, without some such organisation, the work is not likely to be either general or thorough. (8). A firm continuous Government policy absolutely necessary. — Although many of the successful campaigns mentioned above have been due to the enthusiasm and intelligence of individuals, success is not likely to be continued without a determined policy on the part of the Governments concerned. Permanent success is beyond the power of individuals. If Governments wish for lasting results on a large scale, the}' must make up their minds to push the preventive measures at all costs. Laws must be enforced, inefficient officials removed, and the proper expenditure incurred, regardless of popular talk. After all, unlike the prevention of plague and cholera, that of malaria gives little trouble to the public ; but that is all the more reason wh\- it should be prosecuted with resolution. 25. THE VARIOUS PREVENTIVE MEASURES CONSIDERED.— We must now examine the actual preventive measures mentioned at the beginning of last section. f i). Isolation. — Suppose that the number of mosquitoes, and also the number of infected persons in a locality are allowed to remain as before, but that the former are prevented from biting the latter ; then further infection both of insects and of human beings would cease. This means that all the infected persons in a locality are to be isolated from mosquito bites until they recoxer. Not only this, but infected persons outside the locality, and within the range of immigration of mosquitoes, must be treated in the same manner ; and persons entering the locality even for a single night must be examined. This measure may be called isolation of the sick. Again, suppose that the mosquitoes and infected persons are left alone, but that the healthy persons are isolated from mosquito bites. This also would put a stop to further infection ; but healthy persons outside the infected locality, and within range of infected mosquitoes coming from it, must also be protected ; and so must persons who visit the place even for a night. This measure may be called isolation of the healthy. 96 Either of these methods h' itself woukl imply the careful aiifl repeated medical examination of all the persons in a localit}-, and also of visitors. But it is not always possible to sa\-, even after prolonged microscoi^ical search of the blood, whether a person is infected or not ; and many people show the parasites only occasionall}' when the)' suffer from relapses. Others remain infected for years, and would, theoreti- cal 1\-. ha\e to be isolated all that time. To carr)- out all the necessarj' examinations, a large and expensive medical staff \\'ould be required. Hence neither measure by itself is, iisually^ practicable, but both must be combined in a uniform system oi general isolatum from mosquito bites. There is an exception — the case of a localit\- in which only a few cases are beginning to occur. Here such cases may be notified and carefully isolated for the sake of the public. The attempt has been made at Durban, but abandoned ; and it has often been proposed in America. The cases must be controlled with the rigour adopted against plague, \'ellow fever, or cholera, but owing to the long continuance of the malaria infection, for a much longer period. (jcneral isolation from mosquito bites is attempted b}- the use {(i) of culicifuges ; [b) of clothing ; (c) of mosquito nets; and {d) of screens to the windows. Culicifuges are medicaments, such as kerosine oil, lavender oil, and many patent fluids, for keeping away the insects. They ma\' act for an hour or two ; but the effect soon wears off. It is absurd to suppose that a large general population \\ ill c\cr consent to use such substances every day and night, indefinitely for years. The}- are useful (?; only for personal proph)-laxis. The same must be said of special articles of clotliiug — gloves veils, boots. L'seful at special!}- dangerous moments, the}- arc ne\-er likely to be used generally. Mosquito nets round the bed at night are the first essential of personal prophylaxis. For years I have depended entirel}- upon them ; and almost ever}-one of experience in the tropics does the same. I consider that, of all the Anopheline bites which an unprotected person would suffer in twenty-four hours, at least 90 % would probably be inflicted during his sleep at night. Hence, in m}- opinion, the jealous use of a mosquito net reduces the chances of infection anywhere by 90 % ; and though I have been in many malarious places and do not trouble to take quinine, I have only once been infected — and that was 91 before I had ascertained the route of infection. But a small net costs five rupees— the wage of a labourer for ten days in Mauritius. Nets wear out quickly ; it is difficult for the occupants of poor huts to use them for themselves, and .still more for their children ; and they could scarcely be forced by law to do so. Mosquito proofing, or the protection of whole houses or parts of houses with wire gauze, has long been used in the more southern states of America. It is employed (on a great scale) again.st yellow fever and malaria in Panama ; by Sir William MacGregor and Dr. Strachan in Lagos ; and at the Observatory and Central Prisons in Mauritius. " Tinned wire gauze " costs at least twopence a square foot, and brass and copper gauze costs half as much again— besides the cost of construction. The screens are most useful and pleasant. They exclude not only mosquitoes, but other insects and also the glare of the sun and the damp after rain ; and they should certainly be used if possible in all public buildings and in good private houses. The cost is, however, prohibitive for the poor classes of house. Some of these, which are nothing but bamboo and leaf shelters, would practically have to be covered all over, at an expense greater than the value of the structure. Thus proofing is generall)' a measure only for the well to do. There can be little doubt by sections 1 1 and 1 2, that e\-en if a part of the population could be induced to adopt isolation against mosqui- toes the result would be great— the new infections might fail to keep pace with the recoveries, and complete extinction of the disease might follow, especially if case-reduction is adopted in addition. Even for the poorest populations then, isolation must not be neglected : and I shall make definite recommendations under this head in section 31. Isolation can never be complete. People must labour out of doors, where Anophelines frequently bite ; nets and screens get out of order ; and it is especially difficult to isolate children, the principle homes of the parasites. But for the same reasons as apply to mosquito and case-reduction (section 12), the theoretically complete measure is not necessary. Even partial adoption of it max- suffice to break the vicious c}xle. (2) Punkas and segregation— T\i&?,& are measures for the well-to- do. In 1899 I pointed out that Europeans in India are so much more healthy than those in West Africa, probably because they adopt these 98 measures (i). Even in India their health is better in the lari^e can- tonments, where nets, punkas and segregation are generally used, than in the planting districts where the}- are frequently neglected. This has probabl}- been one of the chief causes of the magnificent success of the Indian empire as compared with the comparative failure of the African colonies. Punkas not onl}- keep the body cool, but also drive away a large proportion of flies, and segregation protects from other disea.ses besides malaria. Both are forms of isolation. The latter has been strongly urged against malaria b\- Stephens and Christophers and b}' Button ; and should be used when possible. Without the other measures, it must be ver}- complete to be effective. It failed at Ismailia ; and also at Vacoas, where last January, seventy British soldiers were infected in the barracks, although the infecting native village is more than half a mile distant (addendum 2). Theoretically it is a class measure, and must be accompanied b\- restrictions which are difficult to enforce even with regard to troops, (3) Case-reduction. — Suppose that the number of mosquitoes is allowed to remain as before, and that the\- are not pre\ented from biting, but that the number of infected persons is reduced b)- treatment to zero , then further infection must cease. This means, if cessation of fresh infections is to be immediate, that all infected persons, not only in the locality to be protected, but within mosquito-range outside it, are to be sought out by skilled medical men and treated to the point of complete cure. If gradual reduction is permitted, a more partial measure is still likely to be successful. The detection of cases can be effected only with the difficulty and expen.se referred to under " isolation of the sick." To this must be added the difficult}- and expense of thorough treatment. I infer in section 6 that each case must be treated for several months on the average in order to extirpate the parasites. Moreover, the bulk of the cases are generally the children of the poor ; and the parents of these must be induced to give them the thorough treatment recommended. Repeated examinations will also be necessary ; and infected immigrants must be dealt with— a great difficulty in some cases, for instance that of market towns. For all these purposes a considerable medical .staff is necessary, requiring a constant expenditure. 99 (4) Quiuiue prophylaxis.— T\(x-, is really a form of case-reduction. To the person who takes it, quinine is not exactly a prophylactic It does not exclude the parasites ; it merely destroys them in some cases after the>^ have entered the body. For personal prophylaxis it is valuable at times ofdant^^er ; but as a measure of public prophylaxis it is difficult. We urge, in fact, that every healthy person in a locality shall take the drug continuously in the expectation that he might at any moment be bitten by an infected Anopheline. We thus attempt to provide for case-reduction among the newly infected, as distinct from the old declared infections. But the perpetual use of quinine is always trying to the system, while the contingency of being bitten by an infected mosquito is not always certain ; and many people will prefer the risk of malaria to the certainty of dyspepsia and other symptoms produced by quinine. Moreover I infer, though I am not sure, that as large doses must be taken to quell a new infection as to check an old one— that is. that the prophylactic dose must be as large as the therapeutic one. It is therefore difficult to persuade a large population, consisting let us say of poor labourers, to adopt such a measure continuously. For officials and soldiers it is generally [possible ; but even then is objected to. On the other hand, the general quinine treatment of a whole population, both sick and health)-, saves the trouble and expense of constant medical examination, though it adds to the amount of the drug used. But this difficulty may also be removed by a form of case-reduction, which I shall presentl\- propose for Mauritius— namely the treatment of children with enlarged spleens. (5) Anopheline /r.//.^//^;/.— Suppose that the number of cases is allowed to remain as before, but that the Anophelines are banished, then further infection must cease. This implies, if cessation of infection is to be immediate, that every breeding place of the insects within the area to be protected and also within mosquito range outside it is to be abolished. But a less thorough measure is still likely to produce more gradual reduction (section 12). Mosquito-reduction is based on the certainty that if the bu'th- rate of the insects within a given area is abolished, their numbers will be reduced, not only in that area but for some distance round 7A lOO it ; and will consist hereafter onl\' of chance immigrants from without. The amount of the reduction will var\' as the size of the area treated. The birth-rate is abolished or reduced by complete or partial treatment of the waters in which the\- breed ; by drainage, deepening or filling of marshes and pools by dragging out the water weeds ; by " training " the banks of streams, b}- introducing fish, using oil and other measures. All this requires (a) a capital expenditure and [/>) an annual expenditure ; and can be effected only by a special organisa- tion indefinitely continued. The expense will var\' largeh' according to local conditions. By section 12, malaria will not continue in a localit}- unless the carrying Anophelines are abo\e a certain standard in number. Hence ab.solute suppression of the insects is not necessar\' ; and a mere reduction below the standard should suffice to produce gradual decrease.* Practicall}', Anopheline-reduction may be merged in general ))iosi]uito-reductio}i ^ which costs little more to effect ; and adds great!}' to the advantages of the measure. (6) Public instruction. — Lectures and pamphlets, though frcquentU' repeated, are never attended to by more than a minute proportion of the public ; and even school lessons are soon forgotten. Again, of those who have actuallx' listened to instruction, ver}' few trouble to act upon it. Numerous lectures and pamphlets on malaria will scared}- succeed, perhaps, in inducing one per cent, of the public to be more particular in the use of nets, to take a little quinine for a icw weeks, or to collect broken bottles and tins in their back }-ards ; and in this I speak from frequent experiences. More than these things, the [jri yate individual can scarcel}" dt). lie cannot undertake either case-reduction or mosquito-reduction in his neighbours' houses ; nor force them to adopt isolation. It is well therefore to give public instruction on these matters; but the authorities must not hope to banish, or even seriousl}' to reduce, malaria b}- this means alone. To do so is to abdicate public proph}-laxis altogether — to attempt to throw on the indixidual the duties which can onl}' be done b}- the State. Of course the individual must take his share of the work, but it must be in the form of part payment of the expenses of the concerted measures adopted. Public instruction b}- itself is as useless against malaria as against plague and cholera. * See page 148. lOI 26 THE VARIOUS PREVENTIVE MEASURES COMPARED.- On comparing the above measm-es, the first consideration which must strike the practical sanitarian is the following. Isolat.o and case- reduction require compliance on the part of the public ; mosqu.to- reduction does not. To use culicifuses and mosquito-nets; to put screens to the windows and verandahs ; to take quinine day after day ; to force one's children to take it ; to attend dispensaries for the drug ; and to submit to constant inspections ; require an endless amount of trouble on the part of thousands of people. Will the people take the trouble? What can be done by poor labourers who must be at work at daybreak ; or b>- their wives who labour equally at household affairs > Ha^■e they the time to wait for hours at the d.spensary or to rub unguents all night on their children ; or the money to buy mosquito-nets? And to enforce attention to such detads requires equal trouble on the part of the anthorities-an army of mspectors and medical attendants, and an armomy of laws and regulations What practical sanitarian is there who does not recognise what a 1 this would mean-endless trouble, expense and perhaps friction with the people? On the other hand no one objects to the dramage of swamps and clearing of watercourses, which can be done at once by the authorities without (as a rule) troubling anyone. Here then an immen.se advantage-which will be most apparent to those most experienced in sanitation-lies with mosquito-reduction. Next, case-reduction guards against malaria only; but isolation and mosquito-reduction against all mosquito-borne diseases- filariasis, yellow-fever, and probably dengue and other fevers. Here then, case-reduction is at a disadvantage. Aoain, isolation gives only partial and temporary respite from mosquitoes ; mosquito-reduction, where thoroughly carried o.it, a niuch greater security. The presence of many mosquitoes, especially Stegomyia, is a perfect curse in the tropics. One is bitten all day and everywhere. To get rid of them-even to reduce them-is a great boon I remember Port .Said before and after this was done ; and mam' people have told me of the blessing conferred hy the campaign at Is'maiha-quite apart from the reduction of malaria. Here then, mosquito-reduction again has the ad^antage. , , „„ Lastly mosquito-reduction has a great general sanitary advantage which is not conferred by the other measures. It forces the sanitary I02 department to maintain al\va\'s a minute inspection of the area in its charge — to keej) the \'arcls free from rubbish, the waterways open, the drains free, the cisterns clean, the gardens and open spaces drj-. It tends therefore to become a kind of general insurance polic\- for good sanitation. Hence, theoreticall}-, mostjuito-reduction has the ad\-antage in every wa}'. It does not demand trouble and direct expense on the part of individuals. It does not reciuire the continued use of a nauseous and d\-spepsia-gi\-ing drug. It can be enforced b}' the authorities without troubling the public. It protects from other diseases besides malaria, and also from a general source of anno}-ancc ; and it helps the whole cause of sanitation. Practically however, questions of cost and feasibilit}' have to be considered. It is almost impossible to give an estimate of the cost of mosquito-reduction, which must depend everywhere on the nature of the soil, the slope of the ground, the rainfall, the vegetation, the existence of large marshes, the character of the drainage and of the sanitary establishments already in use, and so on. The figures for Ismailia and the Federated Malay States include large items in excess of the actual anti-mosquito campaign, and those for Panama cannot be obtained. At Port Said the Stcgoi/iyia reduction (complete) costs about sixpence per head of population per annum (section 22). But those who imagine that the other measures will cost much less are mistaken. Consider for example the case of a small town in the tropics containing, let us say, 2,000 tenements and 10,000 inhabitants of all classes — that is, mostl}' poor and coloured people. To supph' them all with ordinary muslin mosquito-nets would cost several thousand pounds, and several hundred pounds a year for depreciation, besides a constant outla\- for inspections. Wire gauze to the houses, even to the better-class houses alone, would add vastl}- to this expenditure. P'^ree quinine distribution, at the rate of eighteenpence per ounce of the drug would cost perhaps iJ^500 a \-ear, if done generalh", without including the large expense of the medical establishment nccessar}', and the endless trouble caused to the inhabitants. It is quite possible that mosquito-reduction for the whole place might be effected in many cases for a fraction of this expenditure. Thus for Ismailia. Pressat reports cmphaticail}- that he was able to do the 103 essential work xvith only four men ! For ^500 a year-which would probably be much less than the cost of medical attendance, qumme, mosquito nets, and wire gauze-we could employ in Mauritius a staff of thirt^• or forty workmen to keep the waterways clear during the ^^•hole year, without troubling the inhabitants at all. I have no doubt which alternative would be chosen by a health officer of experience. Of course, the case may be different x\here there are large marshes with difficult nutlets ; but even here drainage may otten be "recouped by enhanced value of land for buildings, sites, &c., as in the Federated Malay States. For larger towns and cities the case is even more clear. As a rule the cost of Anopheline reduction must vary directly as the size of area dealt with; though in crowded towns it may often be less, owing to so much of the space being occupied by houses and streets. Hence, by draining a square mile of city we shall benefit thousands of people ; whereas by draining the same extent of open country we might benefit onh' a few houses. That is to say, the cost of Anopheline reduction varies as area, not as population. But the expenses for isolation and case-reduction var)- as population and not as area. Hence, I enunciate the follo\\ing general law ; the greater the density of populaiion, the greater the advantages of mosquito- reduction per unit of cost. In rural areas mosquito-reduction ma>^ not be nearly so advantageous. Man)- absurd statements are made on this point b>- people who have never considered the subject properly, and who seem to imagine that the measure is proposed for the world in general. No one has ever made such a suggestion. Mosquito- reduction is for the cit)-, the town, and perhaps the village ; not for the wilderness. We do not propose to drain forests and fields for the good of the birds and beasts. For isolated houses, quinine, isolation, and treatment of small neighbouring waters, if possible, are called for ; but larger N\orks can be indulged in onh- bx' rich house-owners, not by the authorities. Also in small towns and villages situated in the midst of large marshes, or marshy forests, or flat waterlogged countr>-, the cost of mosquito-reduction may be too great. This must not be assumed hastily, without preliminary trials on a small scale ; but, assuming this to' be so, resort can then be had to the other measures. I04 On examining such considerations we shall see that for a large-scale public malaria campaign amongst a general population we are practically reduced to two or three measures. Such measures as the use of culicifuges, mosquito-nets, house-proofing, punkas, segregation, quinine prophylaxis for the health}', cannot realh' be forced on the whole population. The campaign must depend upon mosquito-reduction, treatment of the sick, especially the children with enlargement of the spleen, isolation in certain localities onl\', and regular measurements of the amount of the disease. Hitherto, for convenience of comparison, I ha\-e considered each measure separately, but obviously two or more may be combined. Instead of carrying out each measure b\' itself com- pletely, it might be cheaper to carry out two measures partially. This will be more clearly understood by a study of section i::. For instance, a partial mosquito-reduction combined wirh a partial case-reduction would be likely to have excellent effects. But it is fruitless to consider further such details as these in connection with the general subject, as the\' obviously depend on local conditions. 27. THE GENERAL PREVENTIVE MEASURES SELECTED FOR MAURITIUS. — -I \\ill, therefore, now proceed to choose the measures which, in ni}' opinion, are likely to do most good in Mauritius for the expenditure of money and labour involved. They are the following : — (i) A periodical spleen census of children in schools and on estates. (2) Treatment of children with enlarged spleen in schools and on estates, and a certain amount of quinine distribution. (3) Occasional house protection. (4) Mosquito-reduction where advisable, (a') by minor works, and {d) b\' major works. (5) A suitable organisation and an annual malaria report. Before proceeding to state the details, I should like to premi.se that I do not wish to make rigid recommendations regarding them. Experience will doubtless suggest man}- useful modifications which ma\' safel}- be left to the future. 28. THE PERIODICAL SPLEEN-CENSUS. — The o^Jjccfs of this will be to determine, (i) The localities most affected by malaria ; 105 (2) The effect of the preventive measures ; (3) The children who require treatment. The proposals are as follows : — (i) That a register of all children of fifteen years or under with enlarged spleen be kept at each school by the schoolmaster, and at each estate hospital by the dispenser. (2) That this register should contain the age, sex, and name of the parents of each child with enlarged spleen (but not necessarily of the other children) ; with columns for noting whether the enlargement is small, medium, or great, and a column for remarks. (3) That an examination of all the children attending each school, or living on each estate, should be made every quarter of the year (for the present) by the appropriate medical or sanitary officer. (4) That at this examination the medical officer should select all the children with enlarged spleen, and should direct the proper entries to be made in the register. (5) That twice a year (for the present) the figures in the register of each school or estate hospital should be collected by the school- master or dispenser, and that the result should be forwarded, countersigned by the medical officer, through the proper channels to the Medical and Health Department. (6) That this half-yearly report should give the total number of children attending the school, or on the estate, and the number of children with small, medium, or great enlargement of the spleen. (7) That the half-yearly reports of all the schools and estates should be collected by the Malaria Authority of the Medical and Health Department, and submitted in the form of Table IV of this report to Government (twice a year). (8) The half-yearly reports should be submitted for June and December of each }'ear ; that is, after and before the annual malaria season. (9) For the estates, the half-yearly reports should also give the total number of infants of two years of age or under on the estate, and the number of these suffering from enlarged spleen. (10) The half-yearly reports may also contain remarks by the medical or sanitary officer on the number of the children with enlarged spleen, who, in his opinion, were probably infected at a io6 distance from the school or estate ; and on any local sources ot infection which he thinks ma\- exist. Rcniai-ks. — The census here recommended will evidenth' be made on the lines of that already taken for me b}- the Health and Immigration Departments (section 20) ; but will be still more exact. The quarterh' examinations are required for the purposes of treatment ad\ised in the next section ; and the half-\-earh' reports for the purpose of giving Go\ernment repeated and correct measurements of the amount of malaria present throughout the Colony. The quarterly examinations should, I suppose, be made, on the estates, b}' the medical officers of the estates ; and, in the schools, b\- the sanitar}' wardens, according to the discretion of Government, I do not propose that they shall all be made on the same day or even in the same month. So long as the\' are made once a quarter, the exact date ma\- be left to the convenience of the examiner. I fear that a certain amount of trouble may be caused ; but, owing to the rapidit}' with which children can be examined for enlargement of the spleen, it will not be much ; and as soon as the registers are in order it w ill become less. The information given will be invaluable for the campaign ; and I do not think that an\- other count r}- will have made such an attempt to obtain it. The i}ifaiit spUe)i-rati\ mentioned in (9) above, will be [)articularl}- useful, as it will afford a very correct estimate of the infectio)i-rate on each estate. The percentage of infants, who become infected within two years, will be a good measure of the chances of infection in the localitx' in that [jeriod. I regret much, that I omitted to ask for this information in connection with the spleen-census just taken. The first census under this scheme ma\- I think be carried out in September of this year; so as to prepare for the next malaria season. «il 29. TREATMENT OF CHILDREN IN SCHOOLS AND ON ESTATES. — This measure is the most feasible kind of case-reduction for Mauritius. Its objects are, (i) To improve the health of the indi\idual children ; (2) To prevent them from becoming a source of infection to others. I07 Children arc the principal homes of the parasites, and can be treated more methodicalh' in schools and on estates than elsewhere. ThQ proposals are as follows : — (i) That the examining medical or sanitary officer shall, at each quarterly inspection, indicate the children with enlarged spleen who should be given quinine, and the dose for each. (2) That the quinine should be regularly given to the children for whom it is ordered, by the schoolmaster in the case of schools ; and by the dispenser in the case of estates. (3) That at the next quarterly examination, the examiner shall indicate the children who, he thinks, are no\\' cured ; and also, any children who, he thinks, have become infected since the last examination. (4) That he niay also order quinine (ox children who show no enlargement of the spleen, but who, he thinks, are infected, or likely to become infected, {5) That the quinine be given gratuitousl}- (at least in Government schools); and may be discontinued by order of the medical officer for a child with whom it is found to disagree. With regard to dosage and mode of adininistratioii of the qnini)ie, I would advise that the matter should be left largely in the hands of the medical officers, whose skill will be well proved by the results of the quarterly inspections. They should however report generally in their half-yearly returns on the special system of treatment adopted by them. Personally I have always preferred small and frequenth' repeated doses to occasional large ones — which is also Professor Celli's view. The former method does not disturb the health of the patient so much, and appears to be equally effective against the parasites (which do not seem to become resistant as tr}-panosomes do against atox\d). School children may be given a small dose by the schoolmaster every morning on coming to school ; and it is perhaps particularly necessary to guard against upsetting them b}^ over-doses. But for children on estates, who must visit the hospital specially for the purpose (it is not safe to trust parents to give it^ a larger dose two or three times a week would certainly be more convenient. A ver\^ useful scale of daily dosage is at the rate of one grain of sulphate of quinine (or its equivalent in other salts) for every three years of age, or loS rather, of bulk a[)propriate to age. For dosage twice or thrice a week, one grain for ever\' two N^ears of age is a good scale. I am not much in favour of quinine chocolates, and the like. The form which appears to me the most convenient in every way is that of the freshh' made pill, or other form of bolus, which can be swallowed with water without lea\-ing much taste. Each school may be su[)plied with large bottles or canisters, one containing pills of one grain, the next pills of two grains, and so on. Perhaps it would be safer not to allow pills of more than three grains of quinine for schools. The younger children ma}- be bribed by the present of a sweet to be given after the pill. With the proposed s}'stem (unless a better one can be devised) the examining medical officer visits the school onh- once a quarter, and must consequenth- instruct the schoolmaster as to what he should do during three whole months. It may not be considered advisable to dose the children every da}- during these three months — though this might, I think, be done without danger. In such case it ma}- perhaps be advisable to order that the drug be given onh- during the first fortnight of each month. For the estates, which are visited frequenth- b}' the medical officers, the matter may safel}- be left to them. The drug ma}- perhaps be given for more days during the malaria season ; but should not be stopped during the non-malarious, cool season, which, 1 think, is a ver}- good time to extir|)ate the infection, especially in the older cases with enlarged spleen. Further details, and modifications of the system here proposed, must be left to the Medical Director. 30. OTHER QUININE DISTRIBUTION.— The object is to make as great a reduction as possible in the number of cases of malaria in the colony, with a small expenditure of inone}^ ThQ proposals are as follows : — A. For tozi'HS, villages aiid isolated houses. (i) That five " Quinine Dispensers" be appointed to distribute the drug among the sick b\' means of house to house visitation ; namel}- one for Port Louis, one for Pamplemousses and R. du Rampart Districts, one for Moka and Flacq Districts, one for Grand Port and Savanna Districts, aiid one for Plaines Wilhelms and Black river Districts. 109 (2) Tliat these men be cliil}' qualified dispensers, acting under the Malaria Authorit}- in the Medical and Health Department. (3) That each dispenser shall be stationed at a convenient centre in the area allotted to him, and shall spend the whole of his time in house to house distribution of quinine to those who, he thinks, require it. (4) He shall be provided with a small portable case, which he himself can carry, containing a day's supply of the medicine. (5) The case shall contain six phials or canisters filled with quinine pills of half a grain, one grain, and two, three, four and five grains each ; pills of different sizes being placed in different phials. (6) He shall also be provided with a uniform, or an official badge. (7) On coming to a house he shall offer the quinine gratis to all persons who suffer from fever or enlargement of the spleen. (8) He shall not demand or take any pa\'ment whatever, either for medicine, or for his advice. (9) He shall advise each person who accepts the quinine to take one pill ever)' day, just before the morning meal, and shall give at one time to each person enough quinine for not less than seven da\'s and for not more than fourteen daj-s. (10) The doses given should be as follows : — Age in years 1 1-3 3-6 6 9 9-12 over 12 Age in grains ...... h 1 2 3 4 5 (11) He shall visit most frequently the most malarious localities, according to the direction of the Malaria Authorit}'. (12) He shall not be debarred from giving the quinine, in the doses and to the amount laid down, to any person who demands it, provided that he thinks the person is suffering from fever or enlarged spleen, or is in imminent danger of becoming infected. (13) The Quinine Dispensers shall be well instructed in their duties ; in a knowledge of malaria in general ; and in examining persons for enlargement of the spleen. (14) They shall report briefly on their work once a month, B. For tJie Estates. (i) Every adult on any estate who is known to be suffering from malarial fever or enlargement of the spleen shall be treated in no hospital, or i^iven enoui^h quinine to be taken in his own home during not less than seven da\'s and not more than fourteen daws. (2) The treatment of e\ery such case, either in hospital or out of it, shall not be discontinued imtil the medical officer thinks that the person has been completeK' cured of the infection ; unless good reason is shown for discontinuing it (see section 6). (3) If possible, a report should be made e\er}- haIf-}-ear of the total number of different persons on each estate who have been treated for malaria during the half-year — this report to be included in the one advised for children in section 28 (6). C. Preparation aiid despatch of q/ii)ii)io pills. This will have to be done, I presume, b\' special workers at the Medical Stores ; but I would prefer to leave details to the Medical Department. The pills should be as fresh as possible, and should be despatched in bulk to the \arious destinations. I venture to deprecate any demand for detailed returns regarding their issue b}- schoolmasters and dispensers, as such returns cause much trouble, which will result onh- in decrease of the issue. Leakage will be better ascertained b}' comparing the amounts issued by a school- master or dispenser with the number of persons to whom he has given it, as returned in the half-}'early reports. The pills had better be supplied in large numbers in order to save the trouble, expense, and dela\' of asking for and sending small parcels. Efforts should be made to distinguish (lovernment tiuinine b}- a certain colour, as done in India ; or by stamping the pills or other preparations. The authorities must guard against the possibilit}- of their quinine being subsequenth' retailed to purchasers, or even exported. Too many precautions, however, will have the effect onh- of rin'ning the whole scheme, the object of which is wide distribution, tor the sake of saving a few [pounds of the drug. For the same reasons, efforts to sell it to the well-to-do, while giving it away to the poor, are likeh- to be futile. The cost of collecting the money will probably exceed the ]:)rofits, and the trouble of doing so will limit the distribution. Government must, I fear, face a certain loss from leakage, which should be looked upon as an unaxoidable part of the general cost of the campaign. Remarks. — A s\-stem has already been in force in Mauritius since 1904 by which the drug has been sold or given awa}- by the in masters of thirt}'-five government schools. They have been remunerated at the rate of Rs.30 per annum, for which they kept an accurate register of expenditure of quinine and receipts by sale. During the first eight months of 1907 only 3,803 applications for the drug were made ; and since the commencement of the scheme only about 35 lbs. of it altogether were issued (from 1904 to the end of 1907), although it was given to the general public as well as to sick children attending the school. This amount is insufficient to affect the disease seriously. On the other hand, a dispenser who was appointed to distribute quinine from house to house at Phcenix gave away 20 lbs. of it from January to September 1907. This year, while we were investigating the outbreak at Phoenix, the same dispenser continued this work ; and every week visited about 200 houses, and gave away about 19,000 grains (y ^ lbs.) of quinine to about 650 sick, or nearly 30 grains to each. The result, partly of this and partly of drainage, has been, I hear, the rapid cessation of the outbreak. There is therefore no doubt as to which of the two methods, depot distri- bution or house to-house distribution, is likely to be more effective. My recommendation to appoint house to house Quinine Dispensers is therefore based on the latter method (devised by Dr. Lorans). In fact, experience proves that the sick poor cannot or will not frequently attend schools and dispensaries for quinine ; they must have it put into their hands, or they will not take it at all. I must therefore advise that the old method of general distribution by schoolmasters be superseded by the new methods given above. The schoolmasters will now distribute onl\' to the sick children attending their own institutions (for which I do not think they can ask to be paid). The exact number of Jive Quinine Dispensers has been specified somewhat arbitrarily, and only tentatively. Doubtless experience in working may lead to modifications in this and other details. The Quinine Dispensers may also be used to distribute vermifuges, such as santonine and beta-naphthol, and sulphur ointment for scabies ; and generally to " keep an eye " on sanitary matters. They should be appointed in the Health rather than in the Medical Department. I have said nothing about distribution of quinine at the ordinary dispensaries, as this may be left to the medical officers. I would only suggest that doses for a fortnight or a week at least should I 12 be given to out-patients, in order to save them frequent attendances for the medicine. We must always remember that, if quinine is to be used at all as a general public measure against malaria, it must be poured out wholesale. Otherwise it can have little effect. 31. HOUSE PROTECTION. — The object of this measure is to exclude Anophelines in localities where, owing to large marshes or much forest, they cannot easil}' be reduced. I suggest it chiefl}' as a prospective vicarious measure. The proposals are as follows : — (i) That a small committee, consisting, say, of the Director of the Medical and Health Department, the Director of Public W^orks, the Medical Officer of the Immigration Department, and the Malaria Authority (proposed hereafter), should be appointed to consider if any t}'pe of house can be designed which will exclude mosquitoes, and which can be reasonably insisted upon by building laws for future adoption, especialK- on the estates and for the Indian population. (2) That the Malaria Authority might make experiments with a few Indians' houses, as they are built at present, to see if they can be cheaply protected b}' wire or muslin netting. Remarks. — I have some doubts whether either can be done ; but the attempt would be worth making for places like Post of P'lacq or Petite Riviere, where mosquito reduction would be almost hopeless without large expenditure. In such cases this measure, combined with quinine distribution, seems to be the only refuge. For general sanitary reasons I think it would be highly advantageous to the Colony if better houses could be demanded by the building laws. 1 al\\a\'s like to state as a sanitary aphorism that people live at the level of their houses. Poor and dirty houses mean poor and dirt)' people all over the world. To a large extent, the house makes the man. The opportunit}' ma\- therefore be taken for anew departure in this respect. I can see no reason wh\' coloured populations should not live in better houses in civilised countries. 32. MOSQUITO REDUCTION. — The object of this measure is to keep down the number of Anophelines in certain localities, so that new infections caused b\' them will no longer keep pace with the recoveries, and the disease will consequently tend to die out. 113 This object is attained by removing as far as possible the conditions favourable to the insects. The works required may be divided into two classes, minor and major works. By minor works I mean those which can be continuously carried out without the special services of an engineer, such as the clearing of water channels and drains, release of surface pools, filling of holes, removal of house breeding-waters, cutting of underwood, &c. By major ivorks 1 mean those which require to be designed by an engineer, such as the drainage of some swamps, the canalisation of some streams, &c. By bonification of an area, I mean all the works necessary for reducing mosquitoes in it. The measure is advised, as a rule, only for densely popnlatcd areas. The proposals are as follows : — A. For minor works. (i) That sufficient Workmen be continuously employed in the towns and villages, and on the estates, to do and to maintain the minor works. (2) That a number of men, who may be conveniently called Monstiqniers* be engaged to detect the breeding places of mosquitoes, and to assist otherwise in the works. ^3) That an officer, to be called the Malaria Anthority, be appointed under the Medical and Health Department to superintend the works ; to advise regarding them and other details of the anti- malaria campaign ; and to draw up an annual report. (4) That some legislation ft)r facilitating the works be considered. (5) That some useful administrative adjustments be considered. />. For major %i'orks. That major works for draining, deepening, or filling marshes, or for canalising streams, &c., be undertaken when funds allow^ — {a) If such waters cannot be dealt with efficientl)' or economically by minor works ; and [b) If the neighbouring populatic^n is large enough to justify the expenditure. 33. DETAILS OF MINOR WORKS. — (i) Nature of -works. — The habits of Pyretopliorns costalis, which is responsible for the malaria in * This useful term was invented by Colonel Peterkin, R.A.M.C, P.M.O., of the troops in Mauritius. 8 114 Mauritius, have been well known since 1899. when I described them in Sierra Leone (i). Darut\- de Grandpre and d'Emmcrez de Charmoy haxe added details for Mauritius (13, 14), and have stated that the insect " has the same area of dispersion as the malaria." A full account of the habits is therefore unnecessary here. The insects breed chiefly in stagnant or gentl}^ running water amongst grass and weeds, and also in holes and i)its in the ground, hollows in rocks, cisterns, ponds, " regards " (or pits made in connection with water mains), and so on. The methods of dealing with them are equally well known ; and the Malaria Committee of 1901 has conducted the work absolutely correctl}' since that date. In a letter dated the ist Januar\-, 1908, I advised Government to start minor works at once, so that I might be able to assist in training a number of men during m\- sta\- in the Colon}-. His Excellenc}- the Governor prompth' allotted Rs.6,000 for the purpose ; and with this sum the Medical Department hired ten moustiquiers and ten gangs of three workmen each for the work. These were fair!}- thoroughly trained b\- Major Fowler, Dr. Castel, Dr. Keisler, Dr. Menage, M. d'Emmerez, myself, and others, and did much useful work before my departure. It is therefore unnecessar}' to burden this report with laboured descriptions of details. The actual work re(|uired ma\- be classified as follows : — (a) Keeping clear of weeds anfl otlicr obstructions built street gutters and surface drains. (/-') Clearing of weeds, lex'elling, and discharging roadside ditches and channels. (c) Keeping made water channels clear of weeds and pools. (d) Removing grass, weeds, and pools from the margin of ponds and streams, and rough canalisation of the latter. {e) Discharging, filling, or deepening surface pools where practicable. (/") Discharging leakage from standpipes. (g) Filling (M- oiling certain pits. (/') Concreting hollo vs in rocks and holes in trees. (z) Cutting undergrowth. (/; Dealing with hou.se waters and other useful work in spare time, especiall}' in tlie cooler and drier non-malarious season. 115 (2) Organisation of zvor/xiiioi in gangs. — This is better than to allow each man to work by himself. I generally suggest small gangs of three men each ; a headman at eighteen or twenty rupees a month, and two labourers at sixteen or fifteen rupees — the whole gang to cost fifty rupees a month. The headman must do manual work, but must also be responsible for the others on account of his larger salary. In some places larger gangs may be advisable, and it may prove advantageous to appoint headmen of tried capacit}' on larger salaries for whole localities. Indians of the ///rt// class are especiall}' good at this kind of work, and are generally already experienced in it. Two of our gangs drained considerable areas of the Clairfond marsh b\' themselves. It is astonishing what a large amount of work a gang like one of these will do when constantl}- employed at it. They will clear in one day several hundred \'ards of obstructed water- course, or roughh' canalise a long stretch of stream. The\' become more expert with practice — a further argument for employing them cojitinuonsly. (3) Total nnuibci- of gangs required for Mauritius.— \\. is extremely difficult to form an}^ exact estimate on this important point. The details of other countries are useless, as conditions vary so much. Nothing but experience extending over a year or two can decide the question. Moreover, reduction of the gangs may be possible after the execution of permanent or of certain preliminary works. In a letter dated the i6th January, 1908, I asked Governm.ent for information regarding the total length of water channels, open drains, and roadside gutters, and the annual sum s[)ent for the repair, cleansing, and supervision of them. It was not found possible to give exact details ; but I was informed (Colonial Secretar}-, No 496/08 of 17/2/08) that there were about 800 miles of roadside gutters in rural areas and 296 miles of drains and gutters in towns and villages, or about 1,100 miles in all. It was still more difficult to ascertain the lengths of streams, number of pits and pools, &c., requiring bonification. I was therefore driven to fall back on the personal opinion of men of large experience in the Colony — perhaps the best course from the beginning ; and in letters to the Colonial Secretary dated the 5th January, 1908, I begged Dr. Lorans, Director of the Medical Department, and Dr. Bolton, 8 a u.S direct to the Malaria Authorit}" or other superintendent. I recom- mend that moustiquiers be appointed as follows : — For Plaines Wilhems ... ... ... 3 Port Louis town and district ... ... 2 The other seven districts ... .. ... i each For the estates ... ... ... ... ... 3 There will thus be fifteen of them. The three men for the estates had better live near the Malaria Authorit}' in order to assist him in his inspections or t(^ be despatched wherever he shall direct. The remainder should live at convenient centres. The men had better mosth' be Indians or Mauritius-born Indians of the servant class, who are especialh' apt at the work. The pa\' of the junior five ma}' be put at Rs.20 a month ; that of the next fi\e at Rs.25 ; of the four senior men at Rs.30; and of the head moustiquier at Rs.35. This would stimulate proficienc}'. Their salaries \\ould therefore amount to Rs.4,560 altogether. There is considerable risk in the occu[jation — three of our ten men became badl}^ infected before I left the Colony ; the}' should, therefore, be provided with mosquito nets. Pans for collecting larvs and tra\'clling" expenses are necessar}'. (7) The Malaria Authority should be an officer who is thoroughly acquainted with the subject of malaria and also of mosquitoes and their habits. He should ser\'e under the Director of the Medical and Health Department. He will rctjuire a clerk and office allowance, but should be troubled as little as ])ossible with the correspondence which j)aral}'ses so much work : and an office in his private house would sa\-e much time in tra\elling. He will reciuirc full facilities for travelling. All his time should be spent on su[X'rintending and organising the general campaign against malaria, but examination of mosquitoes and other necessary microscope work will constitute a part of his dut}-, so that he will recpn'rc the necessar}' microscopes and a{)pliances (this does not mean a large laborator}'). Seeing the great importance of the post, I do not think that the .salar}' could well be put at under five hundred rupees a month. Further details of organisation had better be left to the Malaria and Health Department, but I would earnestl}' beg that the holder of the post, while he should be held 119 entirely responsible for success, should be disturbed as little as possible in his important task. Many of the local gangs could with advantage be put under the immediate superintendence of Sanitary Wardens, or Medical Officers, who may be willing to undertake such a duty — which will not be heav}^ It is advisable to bring into pla)- as much local interest as possible. (8) Tools and implements.— T\\q.s& must be sui^plied through the Medical Department, and kept where convenient. I forbear to give further specification of details, which would only hamper the organisation. 34. DETAILS OF MAJOR WORKS.— In reply t(j my request tor information, Government forwarded to me (Colonial Secretary, No. 24/08 of 17/2/08) the excellent minute and annexures of the Hon. M. P. Ic Juge de Segrais, Director of Public Works and Survey's, which are printed in annexure 4, C of this report. In this the Director gives a rough estimate of the total cost of the major works which may be required throughout the island, amounting to Rs.630,000, with an annual expenditure of Rs.44,300 for maintenance by means of 205 workmen with the necessary number of sirdars. This scheme will serve as a base for future work ; but it should be looked upon for the present as an ideal, not to be forgotten, but not to be attempted too soon. The general principle to be remembered in considering the matter is contained in the words, minor i^'orks before nuyor -works. It would be folly to commit the Colony to a large capital expenditure until the absolute necessit\- for this becomes quite apparent ; and it cannot become apparent unless the minor works and other methods of prevention have been tried for some time. The whole area of the island will then have been studied accuratel}- with regard to breeding places ; the working capacities of the gangs \\'\\\ have been gauged ; the marshes and streams which cannot be improved by minor works will have become known ; the disease will have been attacked e\er\'whcre b\- case reduction as well as by mosquito reduction ; and the results will have become apparent. Then, if and where the major works are found to be necessary or economically advisable, the)' should be carried out. But to rush upon the major Ii8 direct to the Malaria Authorit}' or (jther superintendent. I recom- mend that moustiquiers be appointed as follows : — For Plaines W'ilhems ... ... ... 3 Port Louis town and district ... ... 2 The other seven districts ... .. ... i each For the estates ... ... ... ... ... 3 There will thus be fifteen of them. The three men for the estates had better live near the Malaria Authorit}- in order to assist him in his inspections or to be despatched wherever he shall direct. The remainder should li\e at convenient centres. The men had better mostly be Indians or Mauritius-born Indians of the servant class, who are especialK' apt at the work. The pa\- of the junior five ma\- be put at Rs.20 a month ; that of the next fi\"e at Rs.25 ; of the four senior men at Rs.30; and of the head moustiquier at Rs.35. This would stimulate proficienc\\ Their salaries would therefore amount to Rs.4,560 altogether. There is considerable risk in the occupation — three of our ten mcii became badly infected before I left the Colony ; they should, therefore, be provided with mosquito nets. Pans for collecting larx'a^ and tra\clling expenses are necessar}'. (7) Tlic Malaria Aiitlioi-ity should be an officer who is thoroughh' acquainted with the subject of malaria and also of mosquitoes and their habits. He should .serve under the Director of the Medical and Health Department. He will rct^uire a clerk and office alkj\\ance, but should be troubled as little as possible with the correspondence which paralyses so much work ; and an office in his ])rivate house would save much time in tra\elling. He will require full facilities for travelling. .All his time should be s[)ent on su[)erintending and organising the general campaign against malaria, but examination of mosquitoes and other necessary microscoj^e work will constitute a part of his duty, so that he will recjuire the necessar\' microscopes and appliances (this does not mean a large laborator}-). Seeing the great importance of the post, I do not think that the salary could well be put at under five hundred rupees a month. Further details of organisation had better be left to the Malaria and Health Department, but I would earnestly beg that the holder of the post, while he should be held 119 entirely responsible for success, should be disturbed as little as possible in his important task. Many of the local gangs could with advantage be put under the immediate superintendence of Sanitary Wardens, or Medical Officers, who may be willing to undertake such a duty— which will not be heavy. It is advisable to bring into pla\- as much local interest as possible. (8) Tools and //////tv/ZdV/Av.— These must be supplied through the Medical Department, and kei)t where convenient. I forbear to give further specification of details, which would only hami^er the organisation. 34. DETAILS OF MAJOR WORKS.— In repl)' to m>- request for information, Government forwarded to me (Colonial Secretary, No. 24/08 of 17/2/08) the excellent minute and annexures of the Hon. M. P. Ic Juge de Segrais, Director of Public Works and Surveys, which arc printed in annexure 4, C of this report. In this the Director gives a rough estimate of the total cost of the major works which may be required throughout the island, amounting to Rs.630,000, with an annual expenditure of Rs.44,300 for maintenance by means of 205 workmen with the necessar}- number of sirdars. This scheme will serve as a base for future work ; but it should be looked upon for the present as an ideal, not to be forgotten, but not to be attempted too soon. The general principle to be remembered in considering the matter is contained in the words, iiiinor -ivorks before major ivorks. It would be folly to commit the Colon)' to a large capital expenditure until the absolute necessit}- for this becomes quite apparent ; and it cannot become apparent unless the minor works and other methods of prevention have been tried for some time. The whole area ot the island will then have been studied accuratel\- with regard to breeding places ; the working capacities of the gangs will have been '^aueed ; the marshes and streams which cannot be improved by minor works will have become known ; the disease will ha\-e been attacked ever}-where b\' case reduction as well as b)- mosquito reduction ; and the results will have become apparent. Then, if and where the major works are found to be necessary or economically advisable, they should be carried out. But to rush upon the major I20 works without such preHminary experience would be unwise, except in cases where the necessity for them is ah'eady quite obvious. The same idea evidentl}^ underlies paragraph 7 of M. le Juge de Segrais' minute. For example, there was no doubt about the propriety of draining the Clairfond marsh. To deal with it effecti\ely by minor works would have cost more than the interest of the capital expended on the maji:)r work ; it was situated in an important locality, was causing an immense amount of sickness among both the civil and military population, and was threatening Curepipe with a similar epidemic. On the other hand, the drainage of the marshes of Post of Flac(| cannot be recommended with similar cogenc}'. Lastl}-, we must remember that capital spent means interest lost. The sum of Rs. 100,000 would not go far for major works, but the interest of it would support about twent}'-four workmen indefinite!}'. And, moreover, the major work, when completed, would require a certain annual expenditure for maintenance. I therefore recommend after careful consideration that for the present attention be concentrated on the minor works. There are, howe\-er, some major works which, I think, certainl}' do unquestion- abl\- require early execution, namel\', the drainage of the marshes of Curepipe, La Louise, Pamplemousses and Centre of Flacq, and the canalisation of the minor streams of Port Louis (section 36). 35. LEGISLATION AND ADMINISTRATION.— (l) Obviously the economical working of the scheme suggested above will depend largel}' on excellence of administration ; and to assist in this, certain small aiiioidDioits of t/ic hues \y\\\ be useful. T made a careful stud}- of Ordinance Xo. 32 of 1894-95, which is practicall}- the Health .Act in force for Mauritius, and concluded that some additions would facilitate the anti-malaria campaign. These were drafted out and submitted to the Medical and Health Department, and were careful!}' matured b}- the Director, the Acting Assistant Director (Dr. !Momplc). and tlie Procureur-Ceneral. The resulting draft legislation is printed in amiexure 3 of tliis report, and will, I hope, be furtlier considered hy Government. Fvery effort should be made to prevent the abuse of the right of appealing against sanitar}- orders and con\ictions connected witli them (section 24). 121 (2) There is already a considerable saintary staff, consisting of a Chief Sanitary Officer, three Sanitary Wardens, sixteen Sanitary Inspectors at salaries from Rs.960 to Rs. 1,500 a }'ear each, and twenty-two Sanitar}- Guards at salaries of Rs.360 each, costing Rs.52,740 per annum altogether (Blue Book, 1906). Its duties are multifarious — inspections, conservanc}', contraventions, &c. ; but it may be able to give assistance to the anti-malaria work, if the Director thinks this possible. (3) Since the entry of plague in Mauritius in i>S99 there has also been a considerable special plague service, which has been so successful that only about 5,000 cases have occurred since then, the number being now greatl}- reduced. The cost of this service is estimated at Rs. 168,640 for the \'ear 1907-08 (Estimates). Here again help may be given to the malaria service ; while, on the other hand, the latter may also be able to help the former. These matters are not in my province to discuss, and must be left by me to the excellent organising capacities of the Medical and Health Department. (4) On the 1 6th January, 1908, I wrote to Government in order to call attention to leakage from stamipipes which occasionally causes conditions favourable to Anophelines. In replies under letter of the Colonial Secretary No. 493/08 of 22/2/08 and of 17/2/08, it was stated that the defect was due to wear and tear, to thefts and mischievous breakage of taps which the present law does not adequateh' prevent, and to insufficient funds for repair. At Port Louis the Mayor proposed to increase these funds. At Beau Bassin and Rose Hill the Chairman of the Board made the excellent suggestion that a "fountain keeper" at Rs. 18 a month should be appointed to look after the matter, and also drafted legislation on the subject fhis letter No. 1,790 of i7/2/'o8), which I hope Government will consider. (5) In section ^ (3) I alluded to correspondence on roadside ditches, drains, and gutters. It seems possible that the duty of clearing, cleansing, and repairing these could be largely handed over to the malaria gangs, with whose work it is closel}' connected. The duty now lies in the hands of the Public Works Department, which spends about Rs. 6,000 on it ; of the Health Department, which allots a small sinn ; and of the Towns, in which the cost cannot 122 easil}- be extricated from that of conservancy. Port Louis puts the figure at about Rs. 21,000 a }'ear ; Curepipe at Rs.5 — 600 for cleansinjT ; Quatre Rornes at Rs.442 ; and l^eau Rassin and Rose Hill at Rs./io for cleansini^ and repairs. Perhaps the two departments first mentioned might be willing to transfer the money to the malaria service ; while the towns could utilise their expenditure under this heading for forming the nucleus of the malaria gangs which I advised in section ^^ (4) they should possess. (6) On the 14th Januar\-, 1908, I called the attention of Goxernment to the facts that there are in the Colony many i^.urtcr- c/iainicls used for conveying water from ri\ers and springs to ]jlantations and factories, and that they often breed xA.nophelines ; and asked who exactly were the owners, and whether the\' could ncjt be compelled by law to keep them in order, or to fill up those which have fallen into disuse ? Replies were sent to me under letter of the Colonial Secretary Xo. 422 08 of 20-2-08. ]\I_\- letter and the reply of the Procureur-General are printed in annexure 2. PVom the latter it would seem that the channels arc owned b\- private persons who ccnild be compelled, at least after legislation, to do as I suggest. (7) On the 1 6th January, 1908, I \\rote a similar letter regarding the important subject of i/uns/ics 01/ private property. In this I asked whether the owners could be forced by law to drain such marshes, or to pay for the drainage of them by Government ; especiall}- in view of the fact that such drainage might greatly enhance the value of the propert\' ? In repl}' I was informed (Colonial .Secretary, Xo. 497/08 of 30-1-oS) that the question, which presents many diftTculties, had alreafly been under consideration ; that in the opinion of the Law Officer, marshes could not be held to be nuisances in the statutor}- sense of the work ; that legislation had been proposed, but was not eas}^ to effect ; and that H. K. The Governor hopes that xx\\ report would assist in fmding some practical solution of the difficult}-. The answer seems to me to de|)en(l upon the cpiestions [a) whether the existence of the marsh is or is not the fault of the owner; and (/>) whether the remcj\al of it would or would not loenefit the general yjublic as well as himself. Lor instance, if there is in existence a sufficient and practical outfall for the marsh, or other means of dealing with it, in the owner's property, but one which the owner 123 neglects to use, or refuses for his own profit to use ; and if he neglects to render the marsh innocuous by such reasonable minor works as may be recommended b}' the Medical Department ; and if it is proved by the examination of the spleen-rates of the people li\ing near the marsh, or by other methods, that the marsh is actual!}' causing sickness, or, in the opinion of the Medical Department, is likely to cause sickness ; then, I think, he (the owner) may be forced to do the work. As a matter of fact a marsh in a malarious country is a nuisance, because it is certainh' and absolutely a danger to the public health, as known since the time of the ancients, and as recenth' pro\ed b\' the case of the Clairfond marsh in Mauritius (addendum 2); and the fact that this is not recognised by law proves only the inefficiency of the latter. If a person can be forced to remove or cleanse a latrine, he ought most certainh' be forced to remove or discharge a marsh — and for the same reason. On the other hand, if the owner of a marsh has done all reasonable minor works to render it innocuous ; if the major work is bej'ond his means or cannot be carried out on his property' ; and if the marsh is not causing, or is not immediately likely to cause, public sickness ; then I doubt whether he can fairly be forced to undertake the expense. Each case must be judged on its merits ; and in many cases Government would feel it to be more fair to pa}' at least a part of the expense. But I think that legislation to compel the defaulting owner should certainly be passed. In the meantime, however, I recommend (as in the previous section) that attention be concentrated on the minor works. It is only after they have failed, that the major works can be definitely demanded. 36. NOTES ON PREVENTION IN THE TOWNS.-The scheme advised above is a general one ; but I ma}- add a few notes for the Towns. (i) Port Louis. — Major Fowler and I spent ten days in a close inspection of the capital, which constitutes the most thickly peopled part of the small district of the same name (15 square miles). The population of the whole district has recently been steadih' diminishing, as shown at each successive census. Year 1S46 1S51 1861 1871 1881 1891 igoi Population 45,212 49,909 74,128 63,015 66,466 62,046 52,740 124 The decrease commenced after the great epidemic of malaria in 1867, during which year alone one-quarter of the inhabitants died from all causes. It has probabh' been accelerated b\' the facilities gi\'cn b\' the raihva}' to the wealthier inhabitants to sleep in the cooler areas of Plaines Wilhems, and to visit the town only for business during the dax'timc. The death rate of Port Louis has always been in excess of that of the whole island, as shown by the chart in the annual reports of the Registrar-General ; has been steadily rising (apparently) ; and averaged 56'97 or nearh' 57*0 per mille during the seven \-ears 1900-06. It rose to 67'9 in 190] and to 6o'4 in 1903. In 1906 it was I05"6 in the Eastern Area of the town. Out of 2,003 children examined by Dr. Keisler in the schools of Vuvt Louis, 706, or 35*4 per cent, had enlarged s[)leen early this year. The average spleen of all the children was 2'64 times the normal. These are slightly above the means for the \\hole island, but school children gencralh' give lower rates than estate children, of whom there are none at Port Louis, Major Fowler and I, greath- assisted b}- Dr. Keisler, and three moustiquiers, made a careful search for Anopheline larvae. The principal breeding" i)laces are the uncanilised lengths of the three little streams, the Pouce, La Paix, and Trichinopoli streams which traverse the town proper. The two first of these rise in the hills which surround the small plain in which the town lies. High up, their beds are stony and usual!}- nearl}- dr\' except for an occasional pool ; but further down there is running water. The Trichinopoli stream apparentl)- commences from the discharge of a water supply i^ipc. All three when they enter the town are well canalised till the}- reach the sea. Above the canalisation the water runs through grassy borders and breeds numerous Anophelines (photograph 17). A larger stream, the Latanicr river discharges to the east of the town and breeds .1. rf'.y/^?//j>- plentifull}-. There are marshes at Fanfaron Bastion (away from man}- habitations). The insects are also found in the " regards," in oo/.e from leaking water-pipes, and similar waters ; but our men generall}- searched for them in vain in the numerous and well-made stone gutters v.'hich border the streets. There was not much breeding in the Cassis stream ; but the larvae w-ere found here and there in pits, hollows, and channels. On the whole I consider that the uncanalised parts of the 125 four streams first mentioned are responsible for the disease in Port Louis. The spleen rates were high anywhere near them. At Tranquebar, close to pools in the upper part of the Pouce, all out of j2 children suffered — some very severel}'. Generally, near the canalised part of the streams the town appeared to be more healthy, but of course the insects could wander in from outside— though we never found a single Anopheline while we where at Government House. The measures which I recommend are : — [a) The spleen census and treatment of children in schools described in sections 28 and 29. (d) House-to-house quinine distribution (section 30). (c) I would strongly urge that an extensive Jiouse-to-honse spleen census of elu'ldreii in Port Louis sliould be undertaken in September, October and November next. The object of this will be to ascertain exactly which are the most malarious spots, and whether they are contiguous to the uncanalised streams, as I suspect, or to other breeding places, with a view to justifying the major works presently suggested. In 1901 there were 12,876 houses in Port Louis district ; too many to examine thoroughl}', But certain blocks of houses might be taken in the healthiest part, as round Government House, and the results compared with those obtained at — let us say, («) close to the Pouce at Tranquebar and south-west of the Champ de Mars ; ib) east and west of Plaine Vert, south of the Market ; [c) south of the Latanier ; and (^/) near the Cassis streams, i&c. I fear that the labour will be considerable ; but, if enough children are examined, say over 2,000, the results ought to be striking and useful. I suggest that it be done by two or three medical officers, each working a strip between the streams from the sea upwards towards the source of the former, so that each can make his own comparisons. {d) For minor works, rough canalisation of the lesser streams, as frequently shown by me to the Ma\or (Dr. Laurent, who has long taken great interest in the \\-ork) and as largeh' tried by Dr. Keisler, should on no account be neglected after and before the rains. I think that the pools then formed fill the town with Anophelines. During the rains the large floods render such work much more difficult. The frequent leakage from water-pipes, and 126 mosciuito-bi'cedini;" in the " regards " and elsewhere must be dealt with rigorously by sufficient gangs. The Mayor has wisely discouraged too many trees. As he says, " a town is not the place to grow a forest in." At the same time this is a secondary measure, as Anophelines ver\' rarel}- breed in holes in trees. (e) For major luorks \ the I'ouce must ultimatel}' be canalised right up to Junction Road Crossing ; the La Paix and Trichinopoli streams up to Boulevard Victoria. Before, however, recommending anything like the canalisation of the Latanier, an expensive work, I should like to see more evidence that it really causes much sickness, and that cheaper methods will not succeed in reducing the amount it does cause. The same thing must be said of the intercepting drains round upper contours rightly commenced some time ago. If other measures fail, the\' must be proceeded with (on advice by the best engineers). (2) For Curepipe I have nothing to add to the advice given when I was in the Colony — namely to drain the marshes as soon as possible. This can be effected by deepening the bed of the Alesnil ; the cost will not be large ; and the matter has already been urged by many, including the Town Fngineer, M. Hugues. Although there is little endemic malaria in the town, yet Dr. de Chazal's opinion that there is some must be acccj)ted ; and though we could tnul only a few P. cosUxlis in the Curepipe marshes, yet the\- may become much more numerous in the future. The recent outbreak at Clairfond, at the doors of Curepipe, and the case of Cilaos in Reunion, give a warning which it is not wise to ignore. An t)utl)reak at Curepipe will be a most serious affair for the town. Hundreds of the wealthier people and their children would probabl}- become infected ; the value of pro[)ert\' would fall ; and the last slronghcjld against the disease would be conciuered. Cases alread\- occur among the poorer classes to the north, or are immigrating from outside ; and a sudden swarming of P. costalis might easil}- occiu' as the result t>f a hot summer. The outbreak nn'ght be as sudden as disastrous. This is one of the instances in which 1 think a clear case exists for the major works. (3) The marsh at La Louise, Ouatre Bornes, causes considerable 137 sickness and ought to be removed as soon as funds allow. The cost is estimated at Rs. 30,000 (annexure 4, 3). I have no further detail to add regarding the towns, except perhaps a protest against the excessive number of trees at Quatre Bornes and Beau Bassin and Rose Hill. They exhale an enormous amount of damp (as I was informed b\' M. Koenig and Mr. Walter) ; the}' shut out the breeze ; and they breed and shelter mosquitoes. It may be a matter of taste ; but to me a house in the tropics closed in by too many trees is very unpleasant. Perhaps the best wa}' to encourage a reduction of trees on pri\atc properties is to allow the malaria gangs to do the felling in the dry weather when other work is slack, on charge of a small percentage of the wood — or without charge. 37. THE ANNUAL MALARIA REPORT.__This should commence with a tabular statement, giving all the details entered in section 21 of this report, not only for the current year, but for past }'ears for comparison. The general remarks by the Malaria Authorit}' should follow, stating totals of malaria statistics, work done, expenditure, and results. The following tables should be added. Table I. ; School Children. — Average total children, children with enlarged spleen, spleen-rate, average spleen, and children treated in each school ; the averages being made up from the four quarterl}' inspections. Similar figures for the previous year should be given for comparison. Table II. ; Estates. — The same items ; and also infant spleen-rate and average number of adults under continuous treatment, and remarks regarding works done or required. Table III. ; Towns, Villages and Populous Localities. — Follow- ing Dr. Lorans' table (annexure 4 of this report), and gi\ing the number of gangs employed in each place, spleen-rates of local schools and estates, and results. Table IV. ; Major works and their cost. Table V. ; Establishment, salaries, quinine, im[)lements, office and other expenditure. Such a report will enable Government to judge whether or no value is being received for the money spent. 38. MISCELLANEOUS SUGGESTIONS.— (I) Intercepting drains. — Since returning to England 1 have had the advantage of meeting 128 Dr. Malcolm Watson whose l^oocI anti-malaria work is described in section 22. A letter from him, describinL( se\-eral important experiences of his, is t^iven in annexure i ; but he also strongly im[jressed upon me the advantage of draining smaJl marshes b}' intercepting, or so called circum\allator\-, drains in preference to cutting channels through or across the marsh. The former are both cheaper and more effective. (2) Riibble-drains. — These consist of a channel of the requisite depth cut through or round a marsh and filled up with stones — large stones at the bottom and small ones at top. The water percolates through the stones, and is said to carr\' awa}' the silt automaticalh', and the stones pre\'ent the growth of grass and \\'eeds in contact with the water, so that mosqin'tf)es cannot breed in it. They might be tried in con\"enient localities. (3) Stoning irn'gdtwN pits and watcr-cJiannels. — Such pits are fre(|uentl\- made for storing water for irrigating gardens. There are a number (about 10 pits per acre^ close to the prison at Beau Bassin. The}' cannot be filled up without causing hardship ; but the)- can be cemented, or (a cheaper method) lined from edge to bottom with large stones embedded roughl}- in the earth. One of Dr. Castel's gangs dealt with a number of pits close to Pleasance Estate in this manner in a {,). (4) Employment of fifteen moustiquiers (section n). (5) Appointment of a Malaria Authority (section il). (6) Execution of " major works " when called for (.section 34). (7) Appointment of a Committee to consider house-protection (section 31). (8) A special spleen-census for Port Louis (section -i^Q). (9) An annual malaria report (section ij). (10) Some legislation (section 35 and addendum 3). The measures to be adopted over the whole island, and to be 9 A 132 Ks. \>cr annum. . . 6,000 . . 6.000 .. 4,560 .. 65,400 .. 30,000 .. 3,600 .. 1,500 1 gang) •• 5,450 .. 2,000 .. 10,490 started sinuiltaneou.sl}', if [)()ssible before the commencement of ricxt malaria season (section 39\ Tlie approxiuiate cost ma\- be roughly estimated as follows : — Items. 1. Salar}^ of the Malaria Auth.ority ... 2. Salaries of 5 Quinine Dispensers (sa}') 3. Salaries of 15 Aloustiquiers 4. Salaries of 109 gangs (327 men) ... 5. Cost of cjuinine (say) 6. Preparation and dispatch of quinine (sa}') 7. Office of Malaria xAuthority (say) ... cS. Implements, S:c., for gangs (say, Rs. 50 a gang 9. Travelling expenses for staff (say) .. . 10. Margin for possible calls Total ... 135,000 This amounts to ;^9, 000 per amuim, or about Rs. 0*36 per head of population per annum, and \'2 . of Revenue. Xotes. — Item 4 is a rough estimate (section 1}^). The salaries and im|)lements of 13 of the gangs, amounting to Rs. 8,450, ought, I think, to be met by the Towns. Items 5 (7)/d6 may be considerably underestimated. Item 10 should be large, in order to defra\' many expenses wliich ma\- be required at first, especiall}' if a \er}- actixe campaign is under- taken, as ad\ised. The cost of the quinine and possibl}" of the gangs may diminish considerably if tlie campaign is markedly successful (section 24, 5). Major Works. — These, requiring capital expendituic roughly estimated b}- the Public Works Department at Rs. 630,000 for the whole Colon}', are advi.sed to be undertaken, in part, onl\- when and where the other measures ha\e failed ; but early attention is recom- mended to be given to the marshes of Curepipe, La Louise, Pample- mousses, and Centre of I-'lacq, and the streams of Port Louis (annexure 4, C). 133 ADDENDA. ADDENDUM i.- THE MOSQUITOES OF MAURITIUS. — M. d"Emmerez de Charmoy has given me a list of Mauritius mosquitoes. They have aheady l)een studied in Mauritius by him and M. Daruty de Grandpre (14 and 22). Three new species of Culex were obtained during our stay in the Colony, and have been described for us by M. d'Emmerez but the details are unnecessary for this report, and I have published them separately (21.) Anophelines. — I. Pyretophorus costalis Loew iSb6. Proved to be a carrier of malaria in West Africa by myself and colleagues in 1899 (i). The pri)idpal carrier in Mauritius. Abounds round the coast, but also inland and was found by our moustiquiers at Clairfond Marsh (1.350 feet above sea level), where it has been causing the recent outbreak. A few larvae collected at Curepipe. Apparently much more scanty on the plateau than M. Alauritiaiius. Proved to carry malaria in Mauritius by Daruty and d' Emmerez (21). Out of 73 caught at Clairfond and carefully examined during our visit (Daruty, d"P]mmerez, Fowler, Ross), 10 or 13-7 per cent, were infected. Habits already well known. Breeds chiefly in water standing or flowing gently amongst grass and other vegetation and also in bare pools. Caught in houses, verandas, and in the open. 2. Myzorhynclius niauritianus d'Emmerez and Daruty 1900. Very common everywhere in ^Mauritius, especially on the plateau. Abounds at Curepipe. Apparently does not carry malaria. Out of 54 fed on malaria patients only one contained the zygotes, and these we considered by their size to have died after penetrating as far as the stomach wall. Until more experiments have been made however, I am not willing to ^;tate defiiiifely that this species cannot carry malaria under any conditions. All out of 56 caught wild were negative. 3. Xyssorhyuchus maculipalpis Giles 1902. Not common. A few specimens only caught l)y Major Fowler at Fanfaron Bastion, Port Louis, and recently at Clairfond. CuLiciNAE. — 4. Scuiomyia iiotoscripta Skuse 1899. The commonest " Stegomyia " in Mauritius. Abounds in the shade of woods. Bites in the day time. Breeds in tubs, tins, gutters, cisterns, holes in trees and rocks, in Bilbergia spieiuiida, etc. 5. Stegomyia fasciata Fabricius 1805. Common near the sea shore, but more scarce in the highest parts of the island. 6. Culex fatigans Wiedmann 1828. Very common all over the island. 7. Culex tigripes d'Emmerez and Daruty, 1900. One of the largest species known. Conmion in Mauritius. Does not frequenll)' bite man. Larv;^ are cannibals. 8. Culex anfiulioris Theobald 1901. ()nl\- one specimen, taken by Colonel Feterkin, R.A.M.C. 9. Culex ori^wvW/ji n. sp. d'Emmerez de Charmoy (21, 1908). Found in holes in trees at Vacoas, Mauritius. Scarce. 10. Culex ronaldi n. sp. d'Emmerez de Charmoy (21, 1908). Larvae found at Fanfaron Bastion by Major Fowler, but scarce. 11. Culex fozvleri n. sp. d'Emmerez de Charmoy (21, 1908). Prom larva; caught by Major Fowler. Scarce. 134 I have little to add regarding the insects. The leading facts about the commonest species are already quite familiar, and the habits in- general are the same in Mauritius as I have observed them since 1895 ^^ ''t: in many parts of the world (section 2, 3). One fact is worth mentioning. In several parts of India I had observed Stegomyia abounding in woods, but had noted that these insects did not seem always to enter houses (-lose to the woods — suggesting that the former may be oi" a different variety, though possibly of the same species, as those which so frequently persecute the inmates of houses. I observed the same thing in Mauritius. Only a few insects might be in the house at a time when they swarmed in the shade of trees in the garden. It is worth studying whether the house variet}- does not l)reed in pots and tubs, etc., while the woodland variety breeds in holes in trees, bamboo stumps, etc. .Some further facts are given in the following addenda. ADDENDUM 2. — THE OUTBREAK AT CLAIRFOND, PHCENIX.— This epidemic was raging close to the militar}- barracks and to our own house, when we were in Mauritius. It afforded a ver\- good object lesson regarding both the prevalence and the prevention of malaria. I'hcenix is a considerable village situated on the plateau (1,300-1,400 feet above sea level) on the main road from Port Louis to Curepi])e, which there runs in a north-westerly and south-easterly direction. To the west of the road and the village there was, until recently, a large marshy area called the ("lairfond Marsh, made by a number of springs which spread themselves over a flat area (z'/d'r map).* The better class houses lie along the road: but numerous huts of Indians (mostly) exist further west, actually among the pools and streamlets of the marsh. Still further west there is a dry open area traversed by the Riviere Seche, beyond which on a considerable open plain, the well-built barracks of the troops are situated. Further west again there are the villages of Vacoas and La Caverne. 1 o the east of Ph(enix there is open ground rising to the estate called Highlands : and to the south the road rises towards Curepipe (1,800 feet). Until recently, the whole of this area was liealthw in spite of the large marsh; but endemic malaria began to ap])ear in 1903. Dr. de Chazal who has long j)ractised in the neighbourhood has very kindly given me a full history of the e])idemic, wliich I rei)r()(lu(-e below. THE OUTBREAK OF MALARIAL FEVER AT PHCENIX. r>V Dr. Die (JIA/AI,. This village was considered healthy until the \ear 1903, when a small epidemic of malarial fever broke out. I have practised in this District since 1890. Cases of fever among natives had come under my notice from that time : but it was not till the former year that I saw well-to-do people become affected. In my own house, where my ])eo])le had been settled since 1866, a case of malarial lever, of lot-al origin, had never occurred among any member of my family until 1903, when 1 tirst noticed tertian ague and demonstrated the parasites in the blood. (i) The presumed cause of the epidemic. — A part of the "Highlands" Estate, made up of the land now occupied by the Military (lovernment, "Clairfond," and " Mesnil.'' with their marshy ground, was' sold in 1897. The River known under the name of "Riviere Seche" divides this land into two parts. The Military (Government settled to the west of the river, and natives to the east. * Page 186. 135 In July 1898, a regiment of natives from Central Africa was l)rought to Mauritius. The men were taken to Phtenix as soon as they landed. They were not stationed at Port Louis, so as to avoid contracting fever. The men suffered very little from malarial fever, only three cases of ague and one of remittent fever being recorded among them during that year. This regiment left Mauritius in 1900, and during their stay here they had remained at Phoenix exclusively. In 1899 a Bengal Infantry regunent was introduced in Mauritius and quartered at Port Louis, where the Sepoys suffered so much from malarial fever, that they were brought to Phoenix for a change and placed under canvas on the ground now used for polo practice. The services of Army Medical Officers not being available in 1898- 1899, these two regiments were handed over to me ; I had to attend to the sick and to supply medicines. The African regiment suffered from influenza in July and August, 1898, and the Indian Sepoys from malarial fever. The Indians were (juartered in Port Louis and the sick brought up to Phcenix for short periods. In 1902 a second Indian regiment (Rajputs) were brought to Mauritius. The Africans left the island, as already stated, in 1900, the Indians in No\ember, 1906. The sepoys caused a great increase of the Indian civil population at Phtenix, Clairfond and Mesnil villages. Small shops were built to meet the trade opened by the native soldiers. Many new^ huts were erected for the accommodation of a fairly large population of native dealers who travelled all over the island, to and from Phoenix. Of the two Indian regiments, one was kept in Port Louis and the other at Phoenix, alternately, for six months at a time. In order to ascertain if it was the presence of these natives, who settled at Phoenix from the year 1897, that caused an increase of fever in the district, it would be necessary to consult the records of the public dispensaries or the sick rate of the troops quartered at Phcenix camp, but, unfortunately, these records had been kept in such a way that they are not trustworthy until 1906 for the Military Department, and until 1904 for the public dispensaries. All that I can positively state is that I did not notice a marked increase of fever in the district until the year 1903, five years after the arrival of Indian sepoys suffering from malarial infection. (2.) The prevalence of fever in this district prior to the epidemic of 1907 — That fever was prevalent in the district as early as 1892 can be certified by medical practitioners and b)- consulting the records of the public dispensaries. These records, prior to 1904, indicate the total number of attendances, each attendance being reckoned as a separate case ; i.e., if a patient came to the dispensary three times during the year, three cases of fever were entered in the books, whilst since 1904 if the patient came for the same disease more than once only one case of fever was entered. Only the numbers from 1904 will therefore be given. The following table shows the gradual increase of the disease in some of the districts from which the patients who attended at one of the dispensaries, that of A'acoas, were drawn. Years. I'liitnix. Mesnil. Eau Coultie. Caverne. v. Cantons. Solferino. Croisee. Rainfal 1904 .. 41 51 67 81 32 12 52 7646 1905 .. 68 88 71 202 67 55 113 126-86 1906 .. . 107 99 73 506 114 90 170 91'53 1907 .. . 398 152 113 411 109 154 179 92-00 1^6 The information gathered by consulting the Dispensary records are of some value, for they contribute a fair index of the sanitary condition of the district. The numbers given indicate the proportion in which the fever has increased from year to year. The population of these districts can be safely taken as remaining stationary, except that of Phcenix village, which has decreased since the departure of the native regiments in 1906. (3.) T/ie coiirse of the epidemic. — The disease began to make itself very apparent in 1906, although it had alreadv begun to increase in the previous year. The following table shows the total nunil)er of cases of malarial fever at Vacoas Dispensary. Year. 1904 1905 1906 1907 No. of Cases of Malaria. 346 843 1.147 1,487 It was in November, 1906, that the numbers began really to increase at the Dispensary. In March, 1907, the Government started ([uinine treatment and prophylaxis at the patients' homes. The dispensary records would have been higher in the latter year if this had not been done. The rainfall, taken within 50 yards of the Mesnil marshes, is given in inches. The returns from the camp apply to European troops. Military. I'hiLiiix and Mesnil. Rainfall inrhes. Military. I'ho^nix and Mesnil. Rainfal inches /• ■■ 4 10 8-25 4 38 4-13 /•. 1 17 10-79 2 27 10-30 M. .. 8 31 13-99 11 57 8-00 A. .. 16 23 0-88 13 62 14-34 .1/ .. 9 19 8-26 24 66 7-13 /. .. 7 18 3-70 24 60 10-83 J- ■■ 5 13 9-47 28 54 2-61 A. .. 2 10 4-12 13 26 0-16 S. .. 3 9 4 61 22 25 4-61 (I .. 3 12 4-88 8 23 4-88 iV. .. 6 20 1-10 3 40 1-10 D. .. 2 24 11-50 9 72 11-50 £6 206 91-53 161 550 9200 (4) Influence of vicinity of marsli on the causation of fever in neighbouring Jwuscs. — In order to record cases of local infection only those houses are mentioned whose occupants were old settlers in llie district and who had not previously suffered from malarial fever. It nuist be noticed, on referring to the chart which is annexed, that the road leading to Phoenix railway station marks the liniit of the Clairfond marshes towards the north. To the south of this road, there are many springs, streams, and marshes scattered over the area called " Clairfond" and " Mesnil."' The first case of fever occurred in January, 1906, in the house marked I on the chart. The occupants of No. 2 house were attacked in August. „ ,, 3 ,, „ November. „ ,, 4 „ „ December. No. ^17 In 1907 the incidence of the disease was as follows : — The occupants of No. 5 house were affected in February. „ „ 6 ,, „ March. 7 » » April. ,, ,, 8 ,, ,, June. ,, ,, 9 „ ,, September. ,, ,, ro ,, ,, I)ecenil)er In 1908 fresh cases occurred. The occupants of No. 11 house were attacked in January, and those of No. 12 in February. Up to February 20th, 1908, the following houses had not been affected viz. : those marked Nos. 13 to 26 in the chart. 'J'he European soldiers in the Phcenix camp began to l)e affected in January, 1906. Some cases even occurred in 1905 ; but it was not till the month of March, 1906, that the cases became numerous. These examples demonstrate the following facts : — (i) That the houses situated nearest the marsh were affected first. Nos. I, 2, 3, 4, in 1906. (2) That to the north of the road which marks the limit of the marsh, viz. : that leading to Phcenix Station, some houses were affected much later. No. 7 in April, 1907 ; No. 8 in September, 1907 ; No. 9 in December. The other houses situated still further to the north of this road were spared and are still spareci up to this day, February 20th, 1908, viz. : houses Nos. 14-19. (3) That the fever has no tendency up to the present to spread towards the West, along the railway line, beyond the camp, nor towards the North, both these regions being free from marshes or springs. Natives living in these districts are, however, becoming gradually affected. The occupants of the houses mentioned will probably become affected later. The influence of the vicinity of the marsh in causing fever is thus very apparent— the nearer the house is situated to it, the earlier its occupants contract fever. These examples also show that the fever spreads slowly but surely to greater distances from the place where it first broke out. (5) Blackwater Fever. — During the epidemic eight cases of HiX^mo- globinuria fever were noticed at places marked H. on the chart. 'I'hese, it should be noticed, all occurred in the immediate vicinity of the Clairfond Marsh, except one case which occurred in a patient who first lived in a house marked No. 3. He suffered so much from fever in this house that he moved to house No. 27 where he was attacked with Ha^moglobinuria fever four weeks later. These cases show that the type of fever was most severe in the area which is the most marshy : for Hemoglobinuria is considered, and I think rightl}' so, as an index of the gravity of the malarial infection. As a digression, I may mention the following facts concerning these cases of H^emoglobinuria fever. One case occurred in June, 1907 ; two cases occurred in July; two cases occurred in September; one case occurred in November: one case occurred in December, 1907 ; one case occurred in February, 1908. All these cases got well without taking quinine. This drug was administered in some of the cases only after the blood had disappeared from the urine, after and during treatment l)y bichloride of calcium. r38 None of these cases left Phoeni.x. They got well in the same houses where the disease began. These facts are mentioned because it is believed by some medical men that : — (i) The disease occurs in the cold weather. (2) That (juinine hypodermically is the best treatment. {3) That removal to some other place is highly desirable. (6) Remarks aboul Curepipe. — That malarial fever is ])revalent at Curepipe is seen from the records of the Dispensary of that town. The disease shows a marked increase in 1907. s^'^^^ No. of cases of malarial fever. 1904 473 1905 620 1906 644 1907 1,032* The patients who attend at this dispensary come from the town itself and from the numerous " free " villages scattered around, for a radius of from half to three miles. Curepipe attracts a great many people in search of employment, wlio come there already infected by the malarial parasite : but on making a careful enquiry I had no hesitation in stating that there are a good many cases of local infection. The following table shows thu gradual increase in the number of attendances from malarial fevur at the Curei)ipe dispensary and the localities from which these patients come. \'ear. Camp I'ouque- reauN. Riviore Seche. Troll aiix Cerfs. Botanical t'lardens. Forest Side. Old Loretto Convetit. Lower part Curepipe Road. Midland and With mile. Other parts of Curepipe. 1904 20 20 19 12 58 4 45 18 177 1905 16 25 12 16 78 19 55 24 192 1906 21 35 17 17 87 18 111 13 199 J 907 101 49 20 50 133 34 114 54 203 1)K. 1)1 ■: Chazai .'s Re| ::)ort end Is here. On our arri\al Major Fowler and I, greatly assisted by M. Daruty and M. d Emiuerez, and a luimber of mousticiuiers, made a careful study of the epidemic. Our results were as follows : — (i) SpkeJi-ratcs. — These gave most interesting data. We began by examining 163 children collected at Phrenix village, not only from the village, but Iroiii some distance outside it, and found that they had an average si)leen-rate of 55-3 ,. and an a\erage spleen of 3-16. Next we made repeated house to house examinations of 339 children living close to the marsh or a little distance from it, and found an average spleen-rale of yri '/^ and an avenige spleen of 4-12 (Table IV, C). But the important fact was a.scertained that the children living very close to the pools of the marsh had a far higher spleen-rate than those living only a few hundreds of yards away. This confirms Dr. de Chazal's statement based on clinical observations. The spleen-rates, however, give a much more decisive proof of the relation than the clinical observations do, because there is much less statistical error with them, owing to the large number of children examined. * Much of this was probably due to cases from I'hrenix, where there is no dispensary, so that patients often tjo to Curepipe. — R. Ross. 139 Our results are entered in the map in the form of tractions. For example, 3/7 denotes that three out of seven children were found to have enlargement of the spleen. But, owing to the smallness of the map, the fractions are not entered for each house (of which we examined 119), but for clusters of houses. The results however are apparent enough. Near the pools (marked black) the spleen rate is nearly 100%. As we advanced southwards up the slope towards Curei)ii)e the si)leen rate fell at once almost to zero, and remainetl at this all the way there, and in Curepipe itself. At the village of Vacoas and La Caverne (1 '_. to 2 miles from Phuenix) not a single child out of 104 examined had enlarged s])leen ; and on Highlands Estate (i mile), the ratio v.-as only 3 to 50. The rate is high at Phcenix, to the east of the road ; but this is due to a small marsh in the river Mesnil. Hence this interesting house-to-house spleen census gives a most convincing |)roof of the law that )nalaria and Aiiophelines abound most oily vcrv near to breeding places. I do not remember to have read before of the use of the spleen test for obtaining such exact and valuable information. It is evidenth' ca])al)le of similar use elsewhere — wherever we wish to mark down the precise source of tlie disease ; and I have therefore recommended its employment in Port Louis for determining the exact effect of the streams (section 36). (2) T/ie froof'S attacked. i!ut this law is only one of averages, and exceptions occur. Just before our arrival the 2nd Battalion of the Loyal North Lancashire Regiment had come to the barracks at Vacoas. They remained well for a few months ; but suddenly at the end of December, 1907, an epidemic o'\ malaria occurred among them. There were 71 cases in January Some women and children were attacked, and there were five deaths and many invalidings. Yet the barracks are half a mile from the marsh. In addition, several residents in neighbouring houses became infected during our stay. (3) Tlie diffusion of ilie C/airfond Anophelines. \v. order to slud\' this point, I directed a number of the moustiquiers to search for the Anophelines in the houses at Clairfond marsh and at various distances from it. They used to sit up at night with lanterns, and captured the insects that came to bite them. Many were caught at Clairfond, but \ ery few at any distance ; showing that, as calculated by Professor Karl Pearson and myself, migration to a distance is not great. It was reported that the fnigration is greatest on warm still niglits, and least on windy nights — just the opposite to what is generall}' believed. In fiict, cold, rain, and wind seem to make the insects disappear. Very few, and then only M. mauritiamis, were caught in the barracks before I left : but it does not follow, because few are caught i)i a i)lace during the two or three hours when they are being looked for, thnt man)' may not \isit tliat place during a longer i)eriod. One mos(|uito a night on the average means 184 during six months ; and the bite of a single infected mosf]uito means infection. Many of the troops were possibly not infected in the barracks at all, but while walking about in the evening, d'he men used frequently to enter or pass Phcenix village. On the other hand, the cases were decidedly more numerous in the barracks nearest to the marsh. Major Fowler has studied this part of the subject more thoroughly. F. costalis was caught l)oth inside and outside houses, l)ut M. mauritiantis chiefly outside, in verandas, in woods, under baml)oo hedges, and in other sheltered places. Three of our moustiquiers were infected while catching the 140 former. In our own house (number XXIV on the map) we caught only one or two Anophelines (J/, mauritianus) altogether, showing that very few reach a mile from the marsh. (4) Infected mosquitoes at ClairfoiuL All efforts to find the parasites in the M. mauritianus, either caught wild or fed on malaria patients, failed — with the exception of one insect in which dead zygotes occurred. We were therefore for some time at a loss how to explain the malaria, when suddenly one of our men brought in a single P. costalis, which had never hitherto l)een found so high on the plateau. Both this and the next F. costalis caught were found to be infected — thus clearing up the mystery. Subsequently many others, !)oth larva; and adults, were procured in the marsh. Nevertheless they were always much fewer than M. mauritianus — scarcel}' one to fifty. This shows the absurdity of supposing that the infecting mosquitoes in a locality nuist be the most numerous ones there. (5) The output of mosquitoes from a mars/i. I d(j not remember anv previous efforts to ascertain this point. Accordingly, I stretched an ordinary mosquito net over nine square yards of the Clairfond marsh in the manner shown in photograph 23, and counted the mosquitoes caught within it e\erv day. They were all J/, mauritianus, no CuliciuK being found ; and numbered 30 males and 31 females during 16 days, giving an average of 0*423 moscjuitoes per s(|uare yard per diem, or 423 for a thousand square yards. Numbers were still hatching out at the end of 16 days, i )uring the day the adult insects took refuge in the grass, from which thev b.ad to be beaten (uU. Many equally simple experiments could be undertaken with much advantage to practical sanitation. (6) We readily found all species of ///<' parasites in the peoph.' at I'hcenix and neighbouring areas. ij) fSefore 1 arrived, Government had alreach' commenced tcj drain the itiarsh, and a further sum of Rs. 1 1,000 was allotted later on. In addition to this, owing to the representations of H.I'^. the Governor, of General Creagh, CM!., and of Colonel Peterkin, 1\...\.M.(\, the Wax Office gave a considerable sum for the same purpose, in\iewoftlu' outbreak among the troo])s. The marsh was therefore nearly drained b\- the time 1 left. In the meantime the Medical Department had employed a (Quinine l)is]jenser for house-to- house distribution (section 30): and the resuh was that at mv departure infected children were becoming markedlx' more ditlicult to find. I hear that the improvement has been maintained. h\ conclusion, T stroug/y recommend that a second house-to-house spleen census be taken at Phrcnix village in next January, in order to compare the results with those gi\"en in the accom|)anving map. ADDENDUM 3. THE QUESTION OF THE RIVER RESERVES.— 'I'he chiel product of Mauritius is sugar. It has been shown l)y year.s of obserxa- lion thai the amount produced by her magnificent fields varies as ihe rainfall multi[)lied 1)\ the number of rainy days. Now it has long been a dogma of forestry that forests tend to increase the rainfall. For this and other reasons, Mauritius possesses a Forest and Gardens Department, costing Rs. 142, 377 in 1906 (Blue J^ook). Although tlie whole island is well wooded, the true forests exist mostly on the mountains or higher parts of the plateau, where they are carefully guarded by the law. In addition, howe\er, there is an old law which prevents the cutting of trees, without permission of the Forest Department, 141 within a distance of from lo to 50 feet from the edge of certain parts of rivers and streams. The result is that in most parts of Mauritius, wherever there is a small river or stream, or even a stony channel, there is generally found a strip of thick, and sometimes impenetrable, vegetation, consisting both of large trees and underwood, and extending from the stream to the top of the ravine made by it, in the deep shadow of which the water runs along almost hidden from sight. These strips of jungle are called the " River Reserves." Recently the question has arisen whether, whatever may be their good effects, their existence is beneficial to the health of the people who live near them. It has been pointed out that nuisances which tend to pollute the streams (which are largely used for drinking) are often committed in the shelter of the wood, and may cause ankylostomiasis ; and that the water is further polluted by dead leaves of bamboos and other plants, which lie soaking in the pools. More recently. Dr. Bolton, Medical Officer of the Immigration Department, being directed to report on the cause of the high death rate on certain sugar estates, came to the conclusion that on many it was due chiefly to malaria caused by Anophelines breeding largely in these River Reserves (July, 1906). His reports were forwarded for an expression of opinion to the .Societe Medicale, which endorsed his views, and advised " la suppression et le maintien de la suppression des reserves forestieres le long des rivieres dans tout centre de population de la zone malarienne et a 3 et 400 metres en aval et en amont de ces centres " (August, 1906). The matter was now put before the Woods and Forests Board, which considered it at various meetings for more than a year. During the same time the Director of Forests (Mr. Koenig) wrote reports in which he maintained the utility of the River Reserves, and criticised some of Dr. Bolton's conclusions. Finally H.E. the Governor asked me (Colonial Secretary, No. 9,826/06 of 15/2/0S, with correspondence enclosed) for my views on the question. I have carefully considered this literature, as well as reports by Mr. Thompson (1880) and Mr. Gleadow (1904) on the Forests of Mauritius. I also had opportunities to discuss the whole matter with Dr. l,orans, Mr. Koenig, Dr. Bolton, and many others, and will do my l)est to throw some light on the controversy. The first questions which arise relate to matters of fact, (i) Is it really true that forests i/ierease the rainfall? In this connection I had the advantage of being able to read in manuscript an able report on the subject by Mr. Walter, of the Observatory. By analysis of a mass of meteorological statistics he concluded that certain large denudations of forest which occurred in the island some decades ago had certainly had a small but definite effect on the rainfall. The total rainfall had not been markedly changed, but there had been an appreciable decrease of the number of rainy days — one of the most important factors in sugar cane cultivation. From another paper of his (and also from other articles I have read) it would seem that trees suck up moisture by their roots and exhale it into the atmosphere by their leaves in large quantities. On calm days this exhaled moisture increases the humidity of the air until saturation and a fall of rain occur — thus explaining the afternoon showers so frequently seen over the land (but not at sea). Hence trees would be, as it were, syphons which tend to draw up water buried in the soil and to distribute some of it over the fields — in other words, valuable irrigators. 142 But the effect of the whole extensive denudations referred to had not been large. I have unfortunately mislaid my notes on Mr. Walter's report : but if I remember aright there was evidence of only a small percentage of decrease in the number of rainy days. Now the entire extent of River Reserves put together amounts, T l)clie^•e. only to 2 or 3 of the total forest in Mauritius. Hence, I presume, the removal of the entire River Reserves would scarcely diminish the number of rainy days by more than a small fraction. Still further, the proportion of River Reserves and other wooded water channels within 400 metres of populous centres must be only a small fraction of the entire River Reserves and other wooded water channels : so that the removal of these parts only, as advised by the Societe Medicale, would have (I should think) an absolutely inappreciable effect either on the total rainfall or on the number of rainy days. If the denudation of large areas has had little effect, surely that of a few hundred yards of narrow strips of ground near a few populous centres could have scarcely any at all. But other benefits are attributed to the Reserves. It is said that they break the force of the wind on the cane fields ; and I think that they do — but only to a very small percentage on the average. They prevent the water running away too quickly to sea ; they check erosion of the banks by floods and the washing away of the soil by heavy rains. But while admitting these points, we must again remark that it is not proposed to denude all the streams but only small parts of them near " ])opulous centres.'" Now let us turn to the other side. (2) Is it really true that the River Reser7'es cause malaria ^ Dr. Bolton drew his conclusions from a comparison of a number of estates which he divided into two classes, namely. Class A. in which a stream, river, or marsh exists in the vicinity of the Camp, and Class B, in which they do not exist. The death rates for the first half of each of the years 1903, 1904, 1905 tended to be higher in Class A than in Class B : while, taking the average estate death rate for the district as a mean, the death rates of Class A were above ir and those of Class B were below it. Unforiunately, owing to large statistical error, death rates are not very reliable tiuantities for such a comparison. Spleen rates would obviously give much sounder information : and the details for 1907-0S will be found in Table IV, A. These will not necessarily accord with Dr. Bolton's figures, since they were collected twcj years later, and also because, owing to the confusion of names adopted for some of the estates. 1 cannot always identify his localities ; but they generally support his argument. On averaging the spleen rates for the districts I find as follows : — Class A. Cl.-iss 15. Av. Spl. K. Av. Spl. R. ramplcmdusscs ... ... ... 55"7 21'8 Flacq 67-1 53-8 Grand I'ori 68-8 44-0 Savanne 209 27-7 Savanne is the only exception : but the sources of error are so numerous that the figures are worth but little. There may, for instance, be breeding places in Class B not included in those mentioned : while in Class A some of the waters may be too distant to have any great effect. I trust that the spleen census and the results of the minor works proposed in sections 28 and ^iZ ''^'ll definitel\- clear up the question in a year or two ; but at present I cannot say that the Ri\ er Reserves (or more generally the wooded water channels) have been fully convicted of causing all, or even much of the malaria, near them — at least, by statistical evidence. H3 Speaking generally, however, they are certainly dangerous. There is no doubt whatever that the Anophelines do breed in the streams ; but they breed in water along lengths of grassy margin, and in pools in rocks, &c., not in the trees. I am not certain that the trees affect the question much one way or the other. In fact, as pointed out to me by Mr. Koenig, the shade of large trees is inimical to the growth of grass, which is generally scanty under them — and it is grass in ivater which is the danger. Moreover, I can quite imagine that a thick growth round a stream must make ingress or egress much more difficult for mosquitoes. On the other hand, trees do breed Culicin;^, and shelter all mosquitoes ; and our moustiquiers easily captured Anophelines in the Reserves — suggesting that women and children who go to draw water may often become infected there. And the objections to the Reserves on account of nuisances still stand. Before proceeding to consider recommendations, two more points have to be di.scussed. (i) ll is, I think, perfectly agreed to by both sides in the controversy that the undergrowth in the Reserves is quite unnecessary. Mr. Koenig informed me that his department requires the large trees, not the dense growth of useless bushes under them ; and it is precisely this under- growth which the Health Department objects to. There is therefore no reason whatever why it should be retained. The removal, at least near villages and coolie camps, will give free access to the streams not only to the people but to the malaria gangs. Nothing more is required than what was so excellently done by the Forest Department itself to the Mesnil at Phoenix, as well shown in photograph 25. The second point is one which I have heard raised, but which, I think, few will assent to. It is that, if they are of use to the planters, the Reserves should be maintained tven if they do cause malaria. From a humanitarian point of view, this proposition is open to strong criticism. It suggests in brief that human life may be exploited in the interests of individuals. But no civilised state can allow such a thing ; and the Immigration Department in Mauritius has been expressly constituted to protect the indentured coolies. From a rational economical point of view, however, the proposition is still more unsound. If it could be proved that the small parts of the Reserves near populous centres really add materially to the output of the estates, then something might be said for maintaining them. Even then, however, the question would arise whether the loss to the estates from the malaria would not more than counterbalance the gain from the Reserves. People who urge this proposition seem to have completely forgotten this last item. As Dr. Bolton says (annexure i), the day's work of a coolie is worth from R.i"25 to R.i'5o to an estate during the season. When 10 % or more of the men are " down with fever," the loss must mount up to hundreds and thousands of rupees to a single malarious estate during the year. Dr, Bolton adds (iS/7/06) : — " On man}- estates new immi- grants have to be imported to make up for the loss of labour through sickness. They cost Rs.200 each on landing, but in reality a great deal more if the cost of those who desert or die is added to that of those who remain. On some estates more than 25 |' of the new immigrants imported within the last three years have deserted. Add to this 5 % of deaths. The remaining 70 out of 100 men therefore cost Rs. 20,000, equalling Rs.2857 per head for five years, or Rs.57'i4 per year, or Rs.476 per month." He remarks also that numbers of convalescents have to be put to light work, which means that ten men have to do the work of six, and says, " The low price 144 of sugar, the liigh price of transport, labour, and provisions, leave a very small margin, if any, of prolit, so that any economy in the cost of production becomes a matter of serious import." Does anyone suppose that a few hundred yards of jungle planted along a stream is ever likely to compensate a planter for such heavy and constant losses caused by malaria? It therefore seems to me that, if Government is finally driven to decide between River Reserves and malaria sanitation, it would do wisely to clear away the former without much hesitation. P'or the practical needs of the moment, however, my single recoiiuiieiidatio^i is as follows : — The promotion of a bill to a/Iow riverain proprietors to cut down, destroy, or remove any uprooted or dead tree, and also any bush, weed, or noxious growth, found or growing on their property, with proper clauses to notify the Forest Department before this is done, with a view to saving such trees as this department may wish preserved. The bill might be on the lines of the proposed Ordinance of 1905, framed by the Directors of the Forest and .Medical Departments, hut with the compulsory clauses changed into permissive ones. (I understand that the bill was lost owing to these compulsory clauses.) In sections of thu hill the Medical and Health Department might be allowed to do the work after notice. The wood removed might be given to the remover, i.e., the proprietor, the Medical or the Forest Department (if this is possible), whichever does the work. A system must be considered by which the Forest Department will not impede the work either of the owner of the property or of the Medical Department, b\' delay in specifying or notifying which trees are to be left alone (for example, the trees to be preserved may possibly be marked). So far as I can see, this bill would meet all the requirements of the case, and would satisfy all parties. The Forest Department admits that it does not wish to retain the worthless growth, and I believe everyone else wishes to get rid of it. ^fany planters told me that they were only too willing to remove it, but that they were prevented, or hampered, by the laws. If the owner does not wish to do the work, the Medical Department can do it for him. If he refuses permission, I fancy that he could be compelled to give it under the draft legislation in annexure 3— though [)erhaps a special clause will be required to cover this point. The actual work can be done, v,here required, by the malaria gangs, especially during the winter months. I would not advise limitation of the bill to any particular localities, e.g. those near populous places, unless the Forest Department wishes to preserve undergrowth as well as trees in spots far removed from habitations. In conclusion I must add that the exact effect of the streams in causing malaria can be ascertained only by watching the results of the minor works and by taking the spleen census frequently, as already recommended. The facts will declare themselves automaticall\- in the course of the work. Here, as elsewhere, labour lights itself. ADDENDUM 4.— STATISTICAL ERROR. The Poisson formula for statistical error is well known : but it may bu ad\isable to give here an addition made by Professor Karl Tearson, which will be particularly useful for taking spleen rates in villages and towns. Let -A' be the total number of children in a locality : n be the number examined, and .v be the number with enlarged spleen. Then x 100 will be the spleen '•■^te among the « children examined. fiut we shall have no H5 right to infer that ihc .same rate will hold for all the A^ children in the locality. Let f i denote the percentage of error. Then Thus, when ?i = A, (jr all the children in the locality are fxamintd, thi' statistical error vanishes. For example, let X = ^00, n = 200, and x = 100. Then 1 - 7 , - 2 .V {n -.v) about i; and =100. Hence * n J ^ /o = oJ3 = 8-G5. So that we can infer that the spleen rate of the total 800 children is between (50 + 8-65|/ and (50-8-65;| ; that is, between 58-65^ and 41-35^. The following square roots are useful : — ^/2=t-41 ^^/3=l-73 ^/r)==2-24 ^/6 = 2-45 ^/7 = 2-64 /8 = 2-S3 /10 = 3T6. 146 REPORT ON THE PREVENTION OF MALARIA IN MAURITIUS. REFERENCES. . R ° The Pr;v=o.,on of M.hda >n Bnti.h Pos.ess,o„s, h.gyp. a,„, 17 Sept., 1904. Mathematical Theory of Random ^ '^-.::' l^!SS^'com^n.^^tl.ch Memoirs, Umve.it, ot London. Dulau & Co., London, 1906. 6. Report of the Fever Enquiry Conn.nssron, xb66 and 7 Mauritius, 186S. , ,, , , y r Ue-ithnd Edinburgh, 1892. " TKvidson (ieo^raphical Pathology. \ . J. 1 tntianci, jai ^, i s= =~»j;s"«-"rs-;:™r»- mS™,,,. Ke,a.i„n. of fh. Monafify of Maun.iu, .0 the f0- o) i9'-'"- Ross. Ann. rop. Med. c^ ^^^^^^^ °- ^^. ^^^^^ ,f Culex collected D'Emmerez de Charmoy. On ^^^^^f "^ \ -^ • g. Ann. Trop. during the anti-malana campaign n Mauritius 190 Med. and Parasitology, Vol. IE, No 3, 1908. .. Report ofthe Malaria Enquiry Committee, 190T-190- Mau,itiu.,i; , 10. II. 12. 14 16 18. 19, 20 21 147 ANNEXURES. -♦■ ANNEXURE .Extracts from letters by Dr. Bolton to Professor Ross (writtera by request). Lktter A. Ph(KNIX, Jamiarx yd, 1908. In ,go2 I was sent on a specml mission to Diego i;a.cia, one of the '™"X™T*:::[T;;^;t:,^s^t:fts°«ist int,. island the re. cases «t^-i?h™casionally wave among the lahouters tecm.ted ,n Maur.fu., -^-iSrMtv^SarT^^n^d to a,sco.« - ^eas. ma,e.i.W „,alaria tnfection among the res.dent P"V^'°^ ^^^ °s teof the left tl,e Islands. My next step was to "«','; '°;^.'™lf^^f,;, ;„ fiid a single -S;;:^tr nj^^^J'^m^^'-srha^'L^i^-r Jo Lteh .. .. "'""f"! Diego I went to Peros Banhos, another atoll i=o ntiles more to .He east. . Here again I tecotded e^actl^he sat^e fac.s.^^^^ ^_^^_^^ ^^^^^^ ^ Hav,ng always .h'=^'<^ ' ^t Kodn ue ^^ ^^_^^^^.^ ^_^^^^^^ requested my son to investigate the mattei. ■ ne occasion to the resident population is here again due to the fact 'lia ^^„ ^heles- IuhL^ilforerUntof^rs mt^'S ^:t^S Itigh and hreedinl places altnou^n omei y-n 1 , • .| capital of the Island. '^"TLTtos%:"dCe mo:'to';ZV.t co^^ Lia'Ti'.R B. l'H(KNix, 13M A/arc//, 1908. (I) Th. loss to agnctUture resulting from the yearly outbreak of "^^^^^i^e total Indian popuhtion fo,- the wIk.^ I^^kI — ^3^^ -..^90. . and 30,479 children Malaria 1^^ ^^^^^^ ^^^^^^^.^ ^^^,,^ ,, ,,,,,,,. the most n.fectedlocahy the sick^^^^^^^^^^^ population ; on some ^Sr^Sirir^ing dl-s^-'lf'^ta^e^^I^^lu. alto^.her then the «-' MSe'^^r^opnlati^ ™i er^L^y ^7S.^^ ^Z^ L.'r-5o, so that the '°- '» '- o'e^S ^m Rs r";"-; a gi'and' total there- Indians at an average of R. o 2^ per 1"="^ ;^"- ' 5' , » , ^^^^ „^,e fore of close upon Rs. Sco.ooo. The figm.s lelei onl; 148 population residing on Sugar Estates. There must now be added to this the women and chokras who are regular workers on estates ; they also suffer from malaria during the season, and are incapacitated from work for davs and even weeks. The number of women on estates is 24,000 odd. If we accept 50 °/ as a fair figure to represent those working in the fields we obtain a total of about 8,000, and 15 a, on 8,000 is 1,200 — multiplied by 9odays= 108,000 at Rs. o"2o=Rs. 21,000. I do not count the chokras nor the loss to the Estate. I find therefore that the loss to the labourers and their wives and children is Rs. 150,000 nearly. Loss to the Estates Rs. 650,000. 'J'otal Rs. 800,000. The Indian population residing outsid':- estates is over 160,000. A large proportion work as day labourers on estates and also on fibre factories, and about 600 adult males in the different docks in town. Thirty thou.sand adult males, approximately, work as day lal)ourers, earning on an average R. o"55 per diem — a total of about Rs. 15,000 per day — 90 days will represent Rs. 135,000. A loss of 15 2 is therefore Rs 20,000. No mention is made of the loss sustained by the blacks who work as day labourers. I have no figures for these. It is no exaggeration therefore to say that the total loss to the labouring classes amounts to quite Rs. 200,000 and to the planters Rs. 650,000, without taking into account extra hospital expenditure, drugs, comforts, &c. All told it would be found that the grand total would come to (juite Rs. 900,000. Add to this the expense to (lovernment for the sick treated in the different hospitals and at the dispensaries for malaria and sequelae during three months, and the respectable sum of Rs. 1,000,000 is attained. (2.) The next (juestion to deal with is the s[)leen-rates. 'J'here are no schools on the Sugar Estates ; but as ver\- few of the children of the indentured coolies attend school there is no danger of any serious over- lapping. The Indian boys attending the Government schools belong to the free class of Indians, i.e. those who do not live on estates. I am certain the overlapping cannot exceed 0^25 . This is not, I presume, of sufficient import to affe(~t your statistics. Letter from Dr. Malcolm Watson to Professor Ross written by request'.* Ivxsrr ii.i.n, Bkiix.i, n|/ Allan, 26/// Alay, 1908. On the points on which you ask my opinion, my experience is as follows: — (1.) The health of the community shows very great improvement within three months of the abolition of the main breeding places, and malaria was found to have i)ractically disappeared within a year at Klang, although all the breeding places had not been satisfactorily drained. Ex- perience has shown that it is sufficient to reduce the number of mosquitoes in order to abolish malaria, although one naturally aims at making the reduction of the moscjuitoes as great as ])Ossible.t (2) Drainage undoubtedly reduces the luiniber of Anophelines in an area. (3) In both Klang and Port Swettenham there was the most convincing proof that there is no dangerous immigration of Anophelines into a drained area from the outside ; for both towns, although surrounded by an enormous acreage of breeding places, were when drained them.selves freed from malaria. At Port Swettenham the safety zone was certainly less than a (juarter of a mile in some places. * See i^agc 83. t Conijiare pages 34-36. 149 (4) A„ti-n,ala,-ia drainag. can be ffe«'-'>--™f ^'^^^'Vid'Slldl": that it is covered by all spnn- tide., ant mala u^ au « ^^^^^^ successful. Although when a heavy fall of^^^^^J!^^ ^^J X ,all of the tide -™-t^a.:.^t^:,^taSnal 3 2°r:^:?"^^ practice. ANNEXURE ..-CORRESPONDENCE REGARDING WATER CHANNELS. /-,.„, PKO.KSSOK R. ROSS, B«o,„CK, ^•-0■;s ^' T-: HO.OUKA.,,E THE Colonial Secret.arv, M.^urit.us. ,4/*/'"""":'. "J^^- ^IR' , 1 ;,. tl-,^- T^lnnd many water-channels, I have observed that there are '^ ,^ JT^^^^',^^^,, or springs to apparently made for the V-r^o^^^^ cou^y-^^^^^ ^^ P^^^^- ^^^ pbntations or factories, and dso "-^^^ ru,ed W p^^^ . ^^^^^^^^^^^ ^^, ?:s;:;;^r:[ir[;:S;Tls!r:^ -- -^-- along their course. receive for the purposes of my K,.:,-r'"o;;'''M:,rafih*"sfo;U cS;::/ ,„ro,.„,a.,o„ •...,.„„, ..... '■'"""r'T7»-ho,« do th«- belong^to C.overn„,.nt ov .0 the owners of ,he Estates and Factories which they serve? ,, „„,„ers can be .rced^i\*;'^s;r:^^-;;;s.^o :£^^ .^ -„»-m;x rsti^;=u;:;"d:^r::*onprs;:s5^. .- „r.ate ....oses of such owners ? u„. ^r rptnilntion forcing the owners to 3. In the event of there beurg no la. o ^ ^J^^^^^^^^^^^^ Government to keep the channels free trom obstruction tl^us ^-^Pf '^ :-Xich the owners can do the work for sanitary reasons is there an> ^^'^^^'^^ nioreover anv means -n^t:;^^:a::ca:::f^5s^x,ns.a^:^;tr^^ '■'°- S'o°NL.L SKCRLT.V.VS OtfCK, M.«.,<,T, US, .O//, K/.„.,n: .908. '■^' I atrr dtrected by the «o;-ernor to acknowledge U«^^^^^^^ of the 14th ulthrio on the subject ol the cleans.ng ot w.ater J50 transmit herewith copies of the correspondence noted in the margin giving the information asked for therein. Professor R. Ross, C.B., F.R.S., J. MIDDLETOX, IJrodick Vacoas. Assista/if Co/onia/ Secretary. No. O.L. 165/08. From The Honoukaule The Procureur-Genkral to The Hoxourable The Colonial Secretary. Referring to your letter No. 422/08 of the 27th January last on the subject of the cleansing of water channels, I beg to attach a report from the substitute which affords, I submit, an answer to the questions in the letter from Professor Ross. (Sd.) A HERCHENRODER, Prociireur- General. Chamf.ers, \ofh February., 1908. 1. This matter, I understand, recjuires speedy attention, as the stay of Professor Ross in this Island is drawing to a close. I shall therefore deal only with salient features, and omit details. 2. "Canals" are the pnjperty of (^0 private owners, e.g. most if not all, of the artificial water-courses feeding sugar or aloe fibre factories, or established for the purposes of irrigation ; {I)) corporations, e.g. the canals supplying water to the Town of Port Eouis ; {c) connnunities of riverains e.g. the Plaines Wilhems Canal, the Terre Rouge Canal, &c.— I am not cjuite clear whether there are not also some canals which are the exclusive property of Government ; the Director of Public A\'orks and Surveys may give information on this point, which may however, T submit be overlooked, as it does not bear on the more immediate question of legislating, if need be, in order to compel private parties, communities of riverains &c., to take such measures as may prevent the obstructions of canals, and consequently lessen the sources of dissemination of malaria. 3. Private parties are responsible in general for the keeping of their canals in a proper stale of maintenance, repair, cV'c, whether the canals run wholly on lands belonging to such private owners, or ])artly on such lands, and partly on intermediate lands. (See si)eciallv An. 1 :; of Ord. No. -xx of 1863.) V 1 - 4. The same obligation rests on corporations (Ord. No. 35 of 1S63, Art. 46 : Art. 84, S. iii.). 5. It further extends to communities of ri\crains whose rights and duties areregulatedbyChap.il of Order No. 35 of 1S63. Those communities have Syndics (Presidents), and Joint-Syndics (Art. 52 of Ord. No. 35 011863) and keepers (Art. 57). An important provision of Chapter II. of the Ordinance is Art. 64, which enacts that every owner of ground through which a canal belonging to a corporation or ccMimiunily of riverains shall pass (Art. 84, S. iii.), shall be bound to keep the canal in its whole course through his property free from obstructions of any kind, including obstruction by i)lants, branches, roots, &c. (6) I have, I think, given a com])lete reply to (luestion No. i, save on the point of canals which may be the exclusive property of the Crown. Questions No. 2 and No. 3, paragraph i, are partially answered; the cycle will, I think, be complete if an enactment is passed on the lines suggested Ijy Professor Ross in another paper, and which we have discussed with the Medical Director. It includes an addition to the definition of a " nuisance," and powers to suppress, within the shortest delay, breeding places for mosquitoes, to incur the necessary expenses, and to charge them against, and recover them from, the parties concerned. The proposed amendments bear specially on Ord. No. 32 of 1894-1895, Art. 29 scjq. and Art. 52 sqq. Canals coming under categories (a), (/>), and (t) in paragraph 2 of this report are provided for, and the draft enactment further contemplates measures to be adopted in the case of canals and other "premises" which may happen to be the exclusive property of the Crown. The projected law on the prevention of malaria will, I believe, meet the second part of Question No. 3, as well as Question No. 4. Drains and channels will, under certain conditions, be treated as "nuisances" under the general law of 1894-95, or they may be dealt with summarily under the proposed enactment. (Sd.) J. EUC;. SERRETT, 8/2/08. Jg. S.P.G. The above shows, I submit, the necessity of considering the present question simultaneously with the one on which Dr. Momple has conferred with us. 8/2. (ltd.) J.E.S. ANNEXURE 3.— DRAFT LEGISLATION. n • , , ;,r tW'-^ Mauritius, Medical & Health Kegisknd No. D/- ,-. ' ,, c ? / 34. Department, iifh Febniary, 1908. Sir, Referring to your letter of the 5th ultimo, 1 have the honour to transmit for your consideration the enclosed copy of a Draft Ordinance which I think will secure the object aimed at. I have on the whole followed the lines indicated by you, and in the drawing up of the draft the Acting Assistant Director, who has liad particular charge of this work, has been kindly assisted by the Honourable the Procureur- General and his substitute. The imposition of mininum fines, except under special circumstances, is not allowed by the existing legislation. As far as manure and useful bodies of water are concerned, it appears to me that private interests will be sufficiently safe-guarded under both the provisions of Regulation No. 198 of 1907 (of which I annex a copy) and those of the Ordinance now proposed. To Professor R. Ross, C.B., F.R.S., H. Lorans, Brodick, Vacoas. Director. Ordinance No. of 1908. 1. In this Ordinance "owner," "occupier," "premises," "sanitary authority," shall have the same meaning as in Ordinance No. 32 of 1894-95. 2. The following paragraph is added to Article 29 of Ordinance 32 of 1894-95 :— K. All collections of water, sewage, rubbish, refuse, ordure, or other fluid or solid substances, and all other conditions which permit, or facilitate, 152 or are likely to permit or facilitate, the breeding or muUiplication of animal or vegetable parasites of men or domestic animals, or of insects or other agents which are known to carry such parasites, or which may otherwise cause or facilitate the infection of men or domestic animals by such parasites. 3. (a) Notwithstanding tlie above provisions or any of the provisions of Ordinances No. 32 of 1S94-95, 21 of 1900, 23 of 1903, 12 of 1S89, 31 and 32 of 1895. It shall be lawful for any Sanitary Authority or any person deputed by him in writing to take immediate stei)s to destroy mosquito larva; on any premises where they may be found, and to take such action as may be necessary to render any pools or accumulations of water unfit to be breeding places for mcstiuitoes. (/') The persons so deputed shall ha\e a right to enter any premises, dwelling houses excepted, between the hours of six in the morning and six in the afternoon. {(■) A\'hen such pools or accumulations of water lie on premises under the charge of a public body or corporation they shall not be dealt with as above provided, unless due warning has been given in writing to such public body or corporation, and no action has within reasonable delay, not to be less than 24 hours been taken by them. In such cases the ex[)enditure incurred shall be borne by such public body or corporation. (c/) Any owner or occupier who shall object to pools and c(jllections of water on his premises being dealt with as abo\e provided, shall within 24 hours submit his reasons to the sanitary authority, who, after in(]uiry, shall order such action to be taken as he shall consider necessary to meet the provisions of ihis ( )rdinance. Should the objections be rejected the measures originally ordered shall be carried out at the expense of the said owner or occupier. 4. It shall not be lawful for any owner or occupier to allow mosquitoes to breed on his premises or to allow the presence on such premises of any receptacle in whii-h water is kept or may collect uiilos such receptacles are properly protected from access of mosquitoes, or unless the water ihey may contain is treated in such a way as to prevent the breeding Uierein of mos(]uitoes. nor shall such owner or occupier allow on his premises any conditions which nia\-, in any way, l)e fa\ourable to the breeding of mos(]uitoes. 5. Trees on all premises shall be- at all times ke])t freely lopped to the salistaction of the sanitary authority by the owner or occupier, and no trees shall be allowed to grow within 10 feel from an\- dwelling house. The sanitary authority may, in writing, direct the said owner or occupier to carry out the al)o\e ])rovision within a reasonable delay, not to be less than 48 hours, and, in case of non-compliance, the trees shall be lopped or cut down at the expense of the owner or occupier.* 6. It shall be lawful for the Director of the Health Department to maki' such regulations as ma\- be necessary to carry ou[ the provisions of this Ordinance. 7. It shall be lawful for the Director of the Health Department in any case when the owner or occupier of any premises is liable for the expense of * Some specific provision ouglit lo be made to enable the sanitarj- authority to fill up with concrete, or otherwise to treat, holes and hollows in trees which breed, or are likely to breed, mosquitoes; and also to con)i)eI owners U> cut insanitary undergrow th (see ])arlicul'arly addendum 3). R. Ross. 1^3 anj' measures carried out on his premises to relieve such owner or occupier from the said expense, if, after inquiry, the Director is satisfied that such owner or occupier is not in a position to incur such expense. In such cases the expenditure shall be borne by Government. 8. Any person acting in breach of Articles 4 and 5, or of the regulations made under Article 6, shall be lial)le to a fine not exceeding Rs. 100. 9. Expenses incurred by the sanitar_\- authorit}- under paragraphs ((■) and {d) of Article 3, and under Article 5, shall be dealt with in the manner provided by Articles 52 and 53 of Ordinance No. 32 of 1894-95. 10. I'his Ordinance may be cited as the Malaria Prevention Ordinance. ANNEXURE 4.— ROUGH ESTIMATES OF WORKMEN AND WORKS, PREPARED:— (A) BY THE MEDICAL DEPARTMENT. ESTIMATE OF MALARIA (;AN(;S FOR THE RURAL DISTRICTS. . V Pamplemousses. Gangs of _ Gangs of 3 men each. ' ' ^ 3 men each. Populous Places — I Riche Terre and I Tombeau Bay ... i I Arsenal and Riv.Citrons i Villages — Pamplemousses Calebasses ... Terre Rouge Pliane des Papayes and vicinity Ville Bngue Eois Rouge and St. Andre Pte. aux Piments Triolet and Trou aux Biches 4 Total for District, 10. ]' ill ages — Poudre d'or Riviere du Remiwrt. - - Populous Places — I Orand (iaul)e... ... i Cap Malheureux and (Irand Bay... ... i Ooodlands ... ... i Pte. Lascars and Roche Noire ... ... i Riv. du Rempart and Ravin ... ... 3 La Mare and Camp Macons ... ... i Plaine des Roches ... i Total for District, 9 154 Flacq. Gangs of Gangs of 3 men each 3 men each Villages — Populous Places — Centre of Flacq ... Bois d'oiseaux and Po.st of Flacq Plaine Larche I St. Julien ... Bon Accueil and Brisee Trou d'Eau Douce Verdiere I Grand River S. Ea.st La Mare and Australia I Riviere Seche Plaine Gersigny and Richelleau ... (^uatre Cocos... Medine and Mont Ida I r 3 Hots and vicinity ... I 7 8 Total for District, 15. ( iRAND Port. Villages — Populous Places — Mahehourg I Bois des Amourettes Rose Belle I and Coast ... 2 Mare d' Albert I Cent Gaulettes ] New Grove... I Mare Chicose 1 Escalier I Riv. des Creoles and Plaine Magnieu I vicinity I Nouvelle France ... I Les Mares, Bouchon,^:c. 1 Mare Tabac ... I 7 7 Total for Sa\ District, 14. axnp:. Villages — Populous Places — Grand Bois I Camp Berthaud and Souillac I Camp Rataud ] Chemin Grcnier ... 2 Surinam I Riv. de.s Anguilles... 1 Petit Cap r Camp Diable I N.B.- — Toiuuship^ Villages — Vacoas ... 2 Phccnix I Coromandel I Folal for District, 9. Pr.AINKS WiLHEMS. be provided for by Boards. Populous Places — Beau Bassin (outskirts) Mon Roche and \icinity Stanley Quatre Bornes (outskirts) Camp Fouquereaux ... Solferino Curepipe (outskirts), N. & S 4 Total fur District, 1 155 Villages — Petite Riviere : Bambous ... Black River. Gangs of 3 men each Gangs of -x men each. Populous Places — rte. Case Noyale .-• Grande Case Noyale and Chamarel ... ••• Tamarin and vicinity Black River ... Palma and I'ierretonds Flic en Flac ... rte. aux Sables Villages— Moka and St. Pierre Pailles Total for District, lo. Moka. Populous Places Ouartier Militaire ... \ Camp de Masque • . • Montagne Blanche . . . Beau Bois ... ••• Roslyn Cottage and Bois Cheri ... Riv. Baptiste ... Bocage and Mount Ory ReCAI'ITULATION Pamplemousses ... Riv. du Rempart Flacq Grand I'ort Savanne ... Plaines Wilhems ... Black River Moka Additional Totlil for District, 12. Expenditure per Annum 10 9 15 14 9 13 10 12 92 100 100 Gangs 10 Moustiquiers Extra Urban Port Louis— 3 Moustiquiers 4 Gangs ••■ ••• Implements, Sundries, cVc. 60,000 3,000 900 2,400 (3.7 00 Rs.80,000 = n RV THE IMMIGRATION DEPARTMENT. ^''''"^0 "us ":"' O,™,.:, M <-., -. F,....,. -90.. No. 1,117/08- ^- Witb re.rence to your ^-er o|^tbe^* ultii^, ^..^^^^ direction of the Govenror to ^^^"^"^^^^i^^.fion ^Department, on the "Major Dr. Bolton, Medical Officer f , .^^^/j^ ,"\\f ,^ Xrraken on Estates as part of sanitary works of a permanent nature to an anti-malarial campaign. t^^.q^ Kcenig, Professor R. Ross, C.B., F.R.S., ^^^.^.^ Colonial Secretary. Brodick, Vacoas. 156 REPORT.— I.— ON MAJOR SANITARY WORKS OF A PERMANENT NATURE TO BE UNDERTAKEN ON ESTATES AS PART OF AN ANTI-MALARIA CAMPAIGN. Pampkmoiisst's District. Beau Plan Instate. — The factory and camps of this estate, situated in the flat low-lying part of the district, have in their immediate vicinity a large marsh, resulting from tht damming of the discharge canal of all the ponds in the Botanical Gardens. The land all round this marsh is boggy over a considerable area, and contains numberless pools and puddles overgrown with aquatic plants and weeds. The Malaria Committee have under consideration a scheme for the suppression of this dangerous nuisance. In my opinion the most important factor operating in producing high malaria prevalence in one part of the district of Pamplemousses is the state of die banks of the river of the same name. The banks of this water-course are overgrown with a thick jungle, impenetrable in some i)Iaces and composed of brambles, bamboo, raffia palms and weeds of all kinds. Any number of collections of stagnant water exist on each bank. The roots of trees, stones, aquatic plants and vegetable matter in different stages of decomposition, by impeding the flow of water, help to form collections of stagnant water. This most insanitary condition of things from a general, as well as from a malaria point of view, is the result of " the manner in which the forest laws have been applied," and of the " fanatical reverence for trees which is shown by those in charge of river reserves." Besides the above obstacles to the flow of water and the resulting nuisances, several dams exist on this river to supply water to Rosalie-Con- stance, Le Plessis, The Mount, Maison Blanche and I'Esperance Estates and lastly to the Botanical Gardens. Acres of land have thus been submerged, acjuatic plants and weeds have grown, water stagnates and mos(]uitoes abound. 'I'hese estates have always given high malaria percentages on the total deaths, 50-60 % being common figures. The camps of the.se estates have all been built close to the river on account of the water supply. Anti-malaria measures on a small scale will not be of any use. Rosai.ie-Constance, The Mount, Maison Blanche, L'EspifRANCE. — To abate the nuisances existing on these estates will necessitate perhaps alterations in the method adopted in supplying water to the factories of the first two estates ; removing some of the dams, cutting down the trees and jungle on the banks of Pamplemousses river, cultivating the land thus reclaimed, training and l)anking the stream wherever this may be found necessary. But inasmuch as Pamplemousses Village begins immediately after I'Esperance Estate, and as the river flows through part of it, I should say there should be one comprehensive scheme of sanitation embodying the estates mentioned above l\implemousses Village, including the Botanical Gardens and Beau Plan Instate as far as the Royal Alfred Observatory. Needless to say this calls for the interference of the sanitary engineer. Riviere dit Rempart District. The coast line of this district being low and flat i)resents numerous marshes, the most important l)eiiig at I'Union, Poudre d'Or, Haute Rive and Schoenfeld. i!7 L'Union.- — -This at one time large estate has been parcelled out, and we have now to deal with a scattered population living in isolated huts, so that I do not advise any major works. PouiiRK d'Or. — This estate now forms part of St. Antoine Estate. There is a camp with about three hundred souls. In the vicinity of this camp there is a large marsh which empties itself into the sea by a small stream which skirts Poudre d'Or village. Here again any works to be undertaken should comprise the village as well and must be entrusted to a sanitary engineer. ScHOENFKLD. — -There is a marsh on this estate which in my oi)inion is the cause of the high prevalence of malaria. I have not inspected it carefully, so can form no idea of the works which should be undertaken. A careful survey is necessary. Haute Rive. — Several large marshes overgrown with rushes exist on this estate and a river passes through one of the camps. I do not think it will be easy to drain all marshes, as the land is very low and there is barely any fall to the sea, which is quite close. A proper survey and plane tabling will have to be made preliminary to any substantial and permanent work. Flacq District. There is but one estate in this district where comparatively extensive works will have to l)e undertaken. Here again, however, as in the case of Pamplemousses, whatever scheme is eventually adopted should comprise Centre of Flacq Village. The estate alluded to above is Constance (d'Arifat). Constance (d'Arifat) — The portion of this estate where the factory and camps are situated is only a few feet above sea level, very flat and boggy in many places. A sluggish river serpentines through it ; the banks are so Hat that it often overflows. When the water recedes, part remains behind to stagnate in small pits and hollows, and this occurs under the usual thick impenetrable jungle, the river reserves. Besides this one there is another river which comes from Centre de Flacq \'illage to meet it. The above description applies equally well to the latter. Grand Port Dist' ict. Union Vale. — This is the only estate in this district where sanitary works of any magnitude are called for. Between the factory and the hospital exists a marsh which should be drained, but as its oxcrflow runs through private property lower down, I am not in a position to judge the magnitude of the works which may be required. On no estate in the districts of Savanne, , " Plaines Wii.hems, . ,. MOKA, AND PjLack River. are major works necessary in the fight against malaria. Such as may I)e undertaken will be connected with a general scheme for all villages, townships and hamlets and need not be discussed here. If the major anti-malaria undertakings are not numerous in connection with estates, the same cannot be said with regard to 158 II.— MINOR SANITARY WORKS AND MEASURES FORMING PART OF AN AN'ri-MALARL\ CAMI'AKIN ON ESTATES. There is not a single estate in the island upon which, on close inspection, there is not something to be attempted, something done to drive away the fever carrier. All the estates of the island were started long before the memoral)le vear 1867, when malaria showed itself in an cpidtmic form. Isolated cases had been met with long before : in fact, from the beginning of Indian immigration into the island. Mauritius then enjoyed a well deserved reputation for its salubrity. The parcelling out of estates had not begun, and the island was not stocked, as it is now, with agglomerations of Indian huts forming hamlets, villages and camps, inhabited by Indo-Creoles and free immigrants who have served their original indenture. The streams, and even rivers of the island, furnished a supply of pure water or water nearly so. Such being the hygienic conditions prevailing before 1867, all Estate Camps were constructed in the vicinity of streams, in view of an easy and abundant water supply. Alas 1 how altered the ante-1867 local conditions. \\'hal a harrowing picture could a facile pen draw of the present most insanitary conditions to be met with all over the island, from the Morne Brabant in the south to Cap Malheureux in the north, from Port Eouis on the west to 'I'rou d'Eau 1 )ouce on the east. Everywhere the same : polluted rivers, foul boggy moscjuito-haunted jungles on each side ; filth, rank vegetation on the outskirts of villages ; and dark, ill-constructed, unventilated tenements ; with the ever-present Anopheles Mosquito ready to inoculate the first person who hajjpens to come within the range of his jieregrinations. To facilitate reference, I give a list of all estates where a stream or river plays a by no means unimportant part in the malaria endemicity and periodical outbursts. Paniplemoiiss^s. Rosalie, The Mount, Rosalie-Constance, 1 -e Plessis (pari of The Mounl), Maison Blanche (part of Mon Rocher), TEsperance. All these camps are within mosquito reach of Pamplemousses and have already been considered. At Maison Blanche malaria is at times \ery bad. Riviere du Rcfiipa/-t. Haute Rive is the only estate in this district where there is a stream close enough to the camps to operate against the healthiness of the camps. There are two small ones near the two camps of He d'Ambre and a river at Haute Rive. As these camps are, so to speak, within a stone's throw from the sea, the river should be t-leaned, all jungle removed and the banks trimmed. Flacq. In this district the following have water-courses near their camps. Constance (d'Arifat) has already been dealt with under the heading of Major Works. Argy, Beau Bois (a few huts near the river), I propose to have this small camp removed, Belle-Rive, Belle Vue, Constance (M), Deep River, Olivia, Rich Fund and Union. 159 Grand Port. Anse Jonchee, Beau Vallon, Ferney, Joli Bois, Le Vallon, Riche en Eau St. Hubert, Union Park. On all of these, streams or rivers exist with the usual reserves, which have to be attended to. Savaniie. In this district there are numerous streams in too close proximity to the camps. Bel Air, Bel Ombre, St. Aubin, St. Avoid, St. Felix, Sav.mnah, Terracine, have all a heavy malaria percentage on total deaths. With exception of St. Avoid, they are all situated near the coast ; they have no neighbours along the river between them and the sea, so that no possible harm can accrue to any one if the different streams were to dry up after cutting away all the river reserves, a thing I do not anticipate. Plaines Wilhems. Bassin, Trianon, and Eb^ne (part of Stanley) are the onl}- Estates in this district which have filthy streams near the camps. Moka and Black River. The first district is the healthiest of the Island, malaria prevalence low. The Malaria Committee had this district under its consideration in 1902, and with most beneficial results. (See my report on Estate Hospitals for the second half of 1902). In Black River district, Medine Estate has streams near the camp. I propose now to enumerate the Estates where other measures are called for besides destruction of jungle on river side or concurrently therewith : these consist in filling in pits, draining small marshes or filling in as the case may be, searching for old tins, broken bottles, hollow stumps of trees, collections of stagnant water in factories, boilers, tanks, &c., removal of rank vegetation in the vicinity of camps, and lastly a change in the style of hut adopted on Sugar Estates (sanctioned by law) for the housing of the coolies. The system of having long ranges of huts divided into eight, ten, or more compartments, should be condemned, as they favour infection from one to the other — the partition between being never an efficient protection. To obtain a radical change in this direction, the Labour Law and Camp Regulations will need alteration. On the following Estates, collections of water represented by small pools and marshes and tanks will call for special attention : Pampkmousses. Belle A'^ue (Harel) ... Tanks, wells, factory. Belle VueS.E. Co , Mon Piton ... ... ,, old pits, no factory, Mon Rocher ... ... ,, ,, ,, Rosalie ... ... ,, ,, factory. Rosalie Constance ... ,, ,, ,, Solitude ... ... ,, ,, ,, canals, small marshes. Mount ... ... ,, ,, Maison Blanche . . . Old pond, canal L'Esperance ... ... Old pits, canal. i6o Riviere du RefHparf. Antoinette. — Old drain near Mon vSonge Camp. Old disused molass pits in the closed factories of La Lucia and Mon Songe. J^its near manure heaps. Beau Skjour. — If the boilers are not emptied after the crop, they should be kept closed to keep out moscjuitoes. Tanks and other receptacles for water. WvAA.v. Vue-L'Amitik. — Old molass pits at L'Amitie. factory tanks, c\:c. liON Esi'oiR. — Canal, old factory. 1^si'i';rance — Cistern at the wall near the hos})ital, collections of stagnant water. MoN LoisiR (A). — Ponds in \ard near camj). L' Union (R). — Tanks in yard in vanilla plantation. Labourdonnais. — About halfway between the factory and the hospital on the right hand side of the road, I have often noticed a collection of water which in the rainy season will persist for weeks. This should not be allowed to continue. At Forbach, an annex of this estate, the cisterns should be care- fully watched or pro[jerl\- closed to keep out mosquitoes. The same precautions should be taken at .Mai)ou. F/aaj. IJkaux Chami's. Part of the camp of tMs estate has been erected to the leeward and within anopheles range of some Ijoggy lands which are converted into stagnant pools during the rainy season, the j)eriod of greatest malaria prevalence. In presence of the high death rates and persistent increasing malaria prevalence, I have recommended the removal of this part of the camp to a healthier locality. This will soon be an accomplished fact. Deep River. — The reservoir for sup]:)lying the factory of this estate with water is a large pond dug in the earth. The sides are overgrown with brush- wood and rank vegetation in which the water stagnates : although the pond is stocked with some fish, they cannot reach the larva; of the gnats living among the grass in water barely half an inch deep in certain places. An ordinary road separates this sheet of water from one of the estate camps. The necessity of exploring the pond and clearing and trimming its sides is obvious. La Gaiktk.- -Draining and filling in of sonic small collection of marshes. The factory has been closed for years ; as is usual in such cases, open pans, old tanks and pits are to be found : as water ma\- stagnate in them, the\- should be searched for and dealt with. *'. '* Grand Port. 'I'he remarks concerning 1 ,a Caiete apply also lo Anse Jonchee, Ferney, Le \'al!on, X'irginia, as regards sluggish and stagnant water. At La Rosa and New Grove, parts of Rose Bell Estate, Anse Jonchee, Savinia (])art of La P)ara(pie), Sauveterre, Virginia, the factories have been pulled down : old pans, cisterns, molass pits, iS:c., should be carefully investigated and dealt with as cinnunstances mav retiuire. Scn)a)ine. P)KNAREs. — The land all round the reservoir should be kept free of jungle, any collection of stagnant water suppressed. The canal passing i6i through the camp kept cfcan, and the sides propedy .rim„,ed ar.d freed of '"" UUn.on -a large depression next to the camp should l.c carefully watched and no stagnant water allowed tn the ratny seaso,. ^^ S.W.^NNAH.-There .s a d.tch on one sde o ^« 1°«« "y" l,e or less --i;lr":hrb:t;r^«;yc^^^U;:;lul;!properi; trimmed, and '""1 I have already ol«™d the es.tes ..this d. J.t being comparatively one time a marsh had been formed )";;''^e ,7 'y^P^^^' Committee with i;r;!:;is=r;'^- .s^rrr eS\:ti^^o it. orig,na, ... ''"''^J:::::^:'::""^^ or a„y of the e.atesofthe.e.wod,stric.s beyond what I have already written. Execution and Cost of Major Works. I am sorry I a., not n. a position - lay^n e^:^^rox..^-,jhe cost of some of the works to l.e ^^Ttont h sm'eyed vels taken, and separately, and the area to be attacked I ^H^.'^^^^^ the nature of the works to be undertaken spec.fid ^^^^^^^^^^ ,, the I am still of the opmion expressed " . "^^ ;,^P°/\ ';^\„o6 that the Honourable the Protector of Immigrants, -\ ^^^^ f ^^.'./^^A.^^of the island so-called "reserves" should ^'V' -ef to t e pa u n p oprietors, and the where malaria prevails, the wood f^"^^^^ '^^ J^ \h,s be effected, land thus reclaniied cultmated. A very lai^e sau^.^^ ^^^^^^^ ^^^ I ^a/SiJt" "J? r i:Sd at"; m^S: hild o. ... Sth of August, 1906. Minor Works These can easily be undertaken by ordinary Jaboui^rs und^ the^directi^ of a trained overseer; the tools required beinjy.easun^ ^^^^ hoes, pick-axes, crowbars, and baskets. Lach ^listrici gang or gangs distributed over ^^^am areas I pr^^^^^^^^^^^ district into sections, each section to be m charge ot p ^^ ^i^ ^^^ ^^^ One Sanitary (iuard at .•• ' 64 p. m Four labourers at • • • ' • " ' ' ' ^ . Rs.99 p. m ,. ,3 p. ™.;be se..ices of an mtelligent ^^^J^^^Z;; ^a^d'e^o" ^he^dis^^ic^t, ^^:^fi -'S^'s IXerTtt^ rS^^wlfnS be entitled to the refund of any travelling expenses where the > be available. ^2 l62 The Sanitary (kiard will be hound to send weekly reports to his chief showing the area travelled over, the nature of the nuisances detected, and the measures adopted by him to abate them. I believe the following scheme should prove satisfactor\-. I'a/iiphi/iousses. Two sections. Upper and lower. One guard and four men to live at Terre Rouge ... .. Rs.qcj p. m. One guard and two men to live at Plainc des Papayes 67 Rs.i66 The first to patrol as far as the western bank of Pamplemousses River from Rosalie Estate to the sea, and the second over the remainder of the district as far as the boundary of Riviere du Rempart. Riviere du Reynpart. Two sections. The railway line from Pamplemousses boundary to Poudre d'Or Station and the road leading to the village. One guard and two labourers to reside at Piton ... ... Rs.67 And the same number at Poudre d'Or X'illage ... ... 67 Rs.134 Flacq. One guard and four men at centre of Flaccj ... ... Rs.99 One guard and four men at Riviere Seche ... ... 99 Rs.198 'J'lie district to be divided into two sections by the road leading from Camp de .Mas(iue Station to .\rg\- and Palmar. Grand Port. This district can be divided into two sections by the Main Road from Port Pouis as far as the entrance of Plaisance I-^state, thence by a straight line to the sea. One guard and three men to each section ... ... Rs.i66 One patrol to be stationed at Rose Belle and the second at Mahebourg. Sava)iiic. The sinuosities of the Riviere du Bain des Negresses will do very well for the boundary between the two sections of this district. Each to have one guard and three men li\ ing at Chemin Grenier and Riviere des Anguilles ... ... ... R.s.166 Plaiiu's 1 11 //it- his. One guard and three men for Curepipe ... ... ... RS.S3 One guard and three men for Middle Plaines Wilhems including \'acoa, Phcenix, and marked out by a line drawn from west to east and passing through Phicnix Old Mill to the boundary of Moka ... ' RS.S3 Lower Plaines Wilhems. .\11 that remains of the district below that line. One guard and two labourers at Ro.se Hill ... ... RS.7L One guard and two labourers at Coromandel 71 i63 Moka. One guard antl four men at Failles ... ... ... Rs. 99 One man and one labourer to live at Quartier Militaire ... ... ... ... ... Rs. 51 The boundary being a line drawn drawn from the eighth mile post to the mountain and thence to the Piton du Milieu hill. Black River. One guard and four labourers to live at Bambous ... Rs. 99 Total Rs. 1,287 The above figures may be modified as circumstances may recjuire. It is just possible that after the first year the gangs may be reduced in number owing to permanent works having been executed or to some legislative measure by which the burden of keeping up some of the works may be thrown upon the planters and owners of private property. Again the distribution of the gangs may later recjuire modification, in which case it will perhaps be possible to have one guard in charge of two patrols. Major Ross does not say in whose pay the malaria patrols are to be ; from W (a) I should say Government, as these men may be called upon to " distribute (juinine" and to report local outbreaks of malaria. If my surmise is correct, these men ought to suffice for the area allotted to each, as they will have to attend to villages, hamlets, and Indian camps outside Sugar Estates as well as Sugar Estates. Take, for example, the man stationed at Chemin Grenier. He will have Souillac and Chemin Grenier villages. Petit Cap, Bassin Blanc, and Riambel hamlets, Surinam Indian village, Ruisseau Michel hamlet, Chamouny, L'Union Bel Air, Terracine, FonTenelle, and Combo estates, with their camps, numbering all together 13. The distance he will have to travel over will be barely 10 sc^uare miles, for it must be borne in mind that large areas covered with sugar cane will not require inspection. He will have ample time to peer into every nook and corner in search of mosquito breeding places, and even occasionally take charge of quinine distribution in any particular locality. "On almost all the estates of the island the Dispenser Steward has ample leisure during the day to distribute quinine should such a measure be deemed advisable, and to patrol the camps and surroundings. He could be made to report periodically to the Sanitary Inspector of his district on the number of inspections, the area covered by them, the nuisances detectedj the steps taken or recommended by him for the abatement of the same. One man could be told off on each estate to accompany him to perform any little job which he may order. The cost to the estate will be very trifling, about Rs.150 per annum, and the gain ten times that amount. I beg to suggest the appointment of a medical man of Colonial experience in fighting malaria to take charge of anti-malarial measures and the training of patrols and overseers. After a year or two he could be replaced by the Sanitary Wardens attached to the Medical and Health Department unless his permanent appointment be considered advisable. A considerable part of the expenditure to be incurred could be secured by a hut tax, by imposing a licence of Rs. 6 p. a. on each day labourer and by a house tax outside townships where the same is not already levied. The Indians and Creoles in Indian villages, hamlets, and camps outside estates are the principal sufferers from malaria (see what happens at Clair- 12 A 164 fond), they do not contribute to the revenue, and in case of sickness are a burden on the Colonial finances — gratuitous medical aid. The total Indian population of the island may be roughly estimated at 280,000 souls. Of these 99,000 reside on Sugar Estates. So that there is a population of 181,000 to be accounted for. Of these fully 40,000 work as day labourers. A licence of Rs. 6 per annum equal to 2 c. per working day imposed upon every day labourer, Indian and Creoles would bring in K.s. 240,000 p. a. at least. And a house and hut tax ])crhaps considerably more. (Sd.) JOHN BOLTON, Aledical Officer, 18/1 08. Immigration Df.partmext. ANNEXURE 4. — C. BY THE PUBLIC WORKS AND SURVEY DEPARTMENT. X(i. 24/08. Colonial Secretary's Office, Mauritius, \']th Feln-umy, 1908. Sir, With reference to that i)art of your letter dated the 5th January last asking for an estimate of the cost of labour involved in the destruction of breeding places of anophelines, I am directed by the Governor to transmit to you herewith a copy of a minute and annexures from the Director of Public Works and Surveys giving the desired information. Professor R. Ross, C.B., F.R.S., J. MIDDLKTON, "Brodick," Vacoas. Assisfa/if Colonia/ Secretary. P.W'. 67. The HoNOURAiiLE the Colonial Secretary. I have seen Professor on this subject shortly after receiving these papers and have explained to him that to supply to him accurate estimates would take a considerable time, and would mean a very serious expenditure, cer- tainly a good deal more than Rs.300. In fact, it was a practical impossibility to give an accurate estimate within a month's time for instance. 2. Profe.ssor Ross informed me that he only wanted a rough estimate for the purposes of his report, and that the details of each individual work might be entered into later on : that the Medical Director was collecting the information n,'(iuired and would send it on to me as soon as he would get it. 3. On the receipt then of a list of marshes and marshy streams made by the Sanitary Inspectors and controlled by the Sanitary \\'ardens, I had conferences wuh Drs. Momple, Masson, Keisler, and Castel, who kindly had their inspectors in attendance. ^Ve discussed together the points in ques- tion, and I have thus been able to get at a rough estimate of cost, as per Schedule i annexed with fifteen detailed annexures, containing all the information supplied by the Medical Department. 4. I have had the advantage of seeing Professor Ross subsequently, who inspected with me some river diversion drains at Mare aux Vacoas and the water works generally, and I have submitted to him one of the annexures, which appeared to answer his requirements. 5 The total works out at Rs.630,000. Perhaps it would be prudent to add 10 per cent, more making a grand total of Rs. 700,000 to cover any works which may have been left our in the lists submitted to me. i65 schedule 3 gives the probable cost ^^;^^Z. ' i^tot, 'T^^Z be modified of course after a yeat s expeuence, exaggerating. ^ performed, though costly, are 6. I may pomt ou that the ^^o>-ks t j.^^.'.ij.eer's work will come in for not works of art properly so called. ^ ^^^ \'^='f ^^^.^t^^,, of levelhng, with very httle, as all there is to be done comes to a que,tK. ^^^^^^^^ ^^.^^^^^ perhaps one or two exceptions, as in the case ot l^^o. u ^^ probably works of art may be required, not to intertere wi rinarian owners. , ;,w1ami-nt and is active ^ 7. So that any one who has s^ome ^-;-^;^'^;\ .^'^^' t^^sary) and our may with the help of one or several Surveyor (a. ma b.nce >^^^^_ ^^ technical advice (when required) c^i out ^^ -ork ^^1^^^^^ ^^^^^ Government decides to ?^Pl-";/°Ot^ceTn que' don would be the proper works generally, I consider the Office ^'^^1^^^ ,^^^,^ ^i,, jata of the person to be entrusted with the f^^^'^^'^^ to look after, will far Schedules to serve as a base, ancl, having /nrtor of Fublic Works and Surveys. ic^tJi February, 1908. «r,TT~ /-r^cT np DRAINING MARSHES No. Of I'i--- '^i Annexui-e. ^^^ 21,700 1 Port Louis ••• ••• •. 87,590 2 Pamplemousses, Northern section •■ ^ 20,500 3 Pamplemousses, Southern section • ••• - 33,000 Riviere du Rempart '■ ... 64,500 Flacq, Northern section •■■ ••• ■■ ■" .. 17,400 SouUiern section ••• ■• t.m', ^^,,'i"n ■•• 33,500 Plunes Wilhems, Beau Bassin and Rose Hill se.aon .. ^^^ ^^ ^qq ■ ^, Quatre Bornes section ... ••• ••• _ 55300 q " " Vacoas section ... ••• ••• ■'■ "■ 60,000 ^Q '' ',' Curepipe section ... ••■ ■•• ••• ■ 26,000 11 Mok; 41,400 I 19 Cinnd Port, Rose Belle section ■■■ •■• ••• •■• ;" 16,500 W Mahebourg „ -• •• -• - 25,000 14 Savanne':.. - •• - -. ■;.■. ;■.: 63,500 15 Black River - - -^^^ 1 66 SCHEDULE NO. 2 OF PROBABLE COST OF ANNUALLY RECURRENT EXPENDITURE FOR MAINTENANCE OF DRAINAGE WORKS WHEN COMPLETED. No. DistrJLi. i'artirulars ol Labour 300 W'oikiiv^ lk\ 1 Port Louis ... I gang fe 60 " ID men cents. & [ sirilar I ru|iec 2 I'anipleniousses- North South I I " 15 -. 10 ,, " " 3 4 5 Riviere flu Rem Flacq, North South Plaines Will Beau Ijassin Rose Hill (^)uatre Bornes Vacoas .art lenis ami 1 I I I 2 '• 10 „ 10 ,. 10 „ 10 ,, 15 •: 10 „ ; )» 6 Cure])i|)e Moka I I '■ 10 ,, 15 n " " 7 (irand Port, Belle ... Maliebourt; ... \(>se I I •' 15 » 10 ,, " " 8 Savanne I ,. 15 .. ,, „ 9 Black River 2 ij 10 ., , 205 Probable cost Rs. 2,100 3.000 2.100 2,100 4.200 2,100 2,100 3.000 4.200 2.100 3,000 3,030 2,100 3,000 4,200 42,300 DETAILS. DISTRICT OF PORT LOUIS. No, Place. l-) rci|uiiccl. Cleaning and improving on 2 miles ... Do. Draining on a length i)f aliout j mile 200 feet of drain about required. Concerns Dcjiartment. Cleaning and imiirnxingon I mile ... 1 III. 1' mile ... Do. o mile ... Do. 2 miles .. Do. I mile ... 1 Latanier .Stream 2 Terre Rouge River 3 Ste. Croix Marsh 4 I'anfaron Stream 5 I>a Paix Stream 6 Pouce Stream .. 7 Tranquel)ar Stream 8 Cassis Stream .. 9 St. Louis the War No. DISTRICT OF PAMPLEMOUSSES Northern Sectiom Place Description of work^ rciiuired. (■ and plemousses Mon Rocher Terrain Boulle Beau Plan ... imprt )f Rixer 2 nines Draining marsh of about 5 acres .. Draining marsh of about 2 acres ... Draining marsh of about 30 acres with works of art neces.sary for compensation of water rights Ruisscau des Citrons Cleaning and improving stream on 3 miles .St. Andre ... ... Draining marsh Solitude ... ... Draining marsh Probable cost. Rs. 5.000 3.800 1,200 2.500 1.800 1,200 5,000 1.200 21,700 Probable cost. Rs. 5.000 5.000 5.000 50.000 7.500 JO.OOO 5.000 87,500 1 6; DISTRICT OF PAMPLEMOUSSES (Southern Section). No. Place. 1 Riviere Si,-che.. 2 River Tene Rouge 3 Callebasses ... 4 Do. 5 Toml^eau Hamlet 6 Long Mountain 7 Canton Xaney Description nf works required. Iminoving and cleaning stream on a length of three miles along Terra Rouge antl Riche Tcrre Improving ami cleaning stream near La Briquetenc on about i mile Draining marshy lands by side of main road Draining marshy lands near the Infirmary ... Draining marshy lands near Tombeau Bridge on about half a mile ... ... Draining of Mare Sanassee ... Draining marshy lands Probable cost. Rs. 7,500 2,500 3,000 1,000 2,500 2,000 2,000 20,500 DISTRICT OF RIVIERE DU REMPART. No., Place. Description of works required. Citronnier river ... Clearing and imprnriruj Poudre d'Or village ... Clearing of marsh in neighhourhoo Schoenfeld estate ... Clearing of marsh Figette ... He d'Amltre Hermitage Draining of marshes and I'ointe Bourrique Hamlets. Ruisseau Chevrettes ... Clearing and improving on I mde Riviere du Rempart ... Clearing and improving on 3 miles Grand Bay, Hamlet ... Filling ponds Cap Malheureux ... Filling ponds Probable cost. Rs. 2,500 500 5,000 5,000 2,500 7,500 5,000 5,000 33,000 DISTRICT OF FLACQ Northern Section). No. 1 Centre de Flacq 2 River Croignarde 3 Tost of Flacq River . 4 Riviere Francoise 5 Riviere du I'oste 6 Riviere Cere 7 Ruisseau Sarcelle 8 ,, I'ondard 9 ,, Cresson 10 ,, St. Louis .. 11 ,, Grande Barb 12 Mare Jacquot... 13 I'rcividence Hamlet 14 I'risee Verdiere 15 Riche ]\Lare Hamlet . 16 Quatre Cocos... Description of Woiks required. Draining of Marsh • Clearing and improving on aliout 4 miles Draining by about h, mile ot drain ... Clearing of ponds averaging 7 acres Pilling up of ponds Draining small ponils Draining of marshes in neighbourhood Probable cost. Rs. 2.500 10.000 5,000 5,000 7,500 5,000 5,000 2,500 2,500 2,500 2,500 3,500 5,000 1,000 5,000 64,500 1 68 DISTRICT OF FLACQ Southern Section). No. Place. 1 Riv. Seche Village 2 La Lucie 3 Clemencia 4 Etoile Estate ... 5 Sebastopol 6 Belle Vue estate 7 Montague Bamlinus 8 Terrain Dubois 9 Trois Hots ... 10 Bois d'(_)iseau.\ 11 Olivia estate Camp 12 La NfHirrice and Commune La Description of works required. Clearing and improving stream Clearing niarsii Clearing and improving stream on i ,6oo feet ,ooo , , 6oo ,, Clearing marshes on the estate camp ,, and draining Clearing marsh Clearing and imjiroving stream Clearing of marshes ... Clearing and improving of streams on i^ miles Probaljle cost. Rs. 2,500 500 800 1,500 800 1.000 2.000 500 2,000 1,000 1.000 3,800 17.400 DISTRICT OF PLAINES WILHEMS Beau Bassin and Rose Hill Section . No. PI.-ice. r'escri|5tion of works required. Probable cost. Rs. 1 Plaines Wilhems River Improving and clearing river on a length of 2 miles 5,000 2 Aliphon's premises. Ruse Hill ... ... (letting rid of marshes formed by masonry channel 2,500 3 Ciillector from lidvvard VII. .Street to Plaines Wilhems River ... Large repairs to masonry conduits ... ... ... 2.500 4 ("orps de Garde .Moiin- Draining marsh on the north and eastern side of the 5,000 tain. mountain. 5 Summerfield drain. Beau Re])airs to channel and dispo.sal of the water in 3.500 Bassin. absorjjtion well. 6 Beau Ba.ssin, between Construction of a large open drain in fairly rocky 15,000 Alice Mangues and ground on aljout 5,000 feet. Maingard -Street. 33,500 DISTRICT OF PLAINES WILHEMS Quatre Bornes Sections No. Pl.-ice. Descri|)tion of works required. 1 La Louise ... ... Draining of marshes to discharge at La l-'enetre ... 2 riaines \Vilhems River Clearing and improving river on 2 miles 3 Riviere Seche, behind Trianon Instate ... Draining marshes (small) 4 Beau Scjour ... ... ,. ., 5 Mesnil River Clearing'and improving river from Phrenix Old Mill to junction wiih Plaines Wilhems River. Length 2 miles 6 .Solferino ... ... Clearing of stream terminating in neighbnm-hood of Solferino on a length of 3 miles ... 7 Papayes River ... Clearing and improving river on 2 miles ... . . Probable cost. Rs. 30,000 5,000 1,000 1.000 5.000 7,500 5,000 54,500 1 69 DISTRICT OF PLAINES WILHEMS (Vacoas. No. Place. 1 Clairfond 2 River Plaines VVilhems 3 River Camp Fouque- raux 4 River Terre Rou!j;e . . . 5 Allee Brillant and Camp Fouqueraux 6 Phrenix 7 Perichon stream 8 Papayes River 9 Riviere du Rempart .. 10 Rivers Tatamaka aiK Si. Martin 11 La Croisse 12 Alesnil River 13 Riviere Seche Uescription of works required. Draining of marshes, already provided for. Clearing and improving on 2 miles ... ,, ,, i| miles ... Marshy streams in the neighbourhood of these roads to be drained on a length of about 5)000 feet Marshes caused by War Department Sewerage works. Should be removed by War Department Clearing and improving stream on i mile ... Clearing and imjiroving stream on i mile in the neighbourhood of Camp Mapou and Camp Roshc Clearing and improving on about 25,000 feet Clearing and improving on about 30,000 feet Clearing and improving 2 feeders of Riviere du Rempart on 3,000 feet Clearing and improving from Allee Brillant to Phoenix Iron Bridge on a length of about 3 miles ,, ,, ,, about 2 miles Probable cost. Rs. 5.000 5,000 3,800 5.000 2,500 2,500 12,500 15,000 1,500 7,500 5,000 65,300 No. DISTRICT OF Place. 1 River Mesnil ... 2 Do. 3 Do. 4 Do. 5 Do. 6 Eau Bleue River 7 I'oule d'Eau Ri\er 8 Do. 9 Riviere Seche... 10 Do. 11 Curepipe generally No. Place. 1 L'llsperance ... 2 Providence Lesur 3 Moiitagne Blancht 4 PaiUes 5 La Dagotiere . 6 Alma Estate ... PLAINES WILHEMS (Curepipe Section). Description of works required. Draining marshes near Town Hall ... Deejiening stream on about 2,500 feet Draining marshes on Forest side portion Deepening ilrain along Lees Street Improving course of stream from D'Arifat Street to Allee Brillant, about 10,400 feet Improving course of stream on about 9,700 feet and draining marshes connected therewith ... Cutting bed of stream on 3,000 feet Improving course of stream on 12,600 feit Improving course of stream on 34,300 feet as far as Allee Brillant Improving course of stream on western side of Curepipe on 5,600 feet ... Draining other small marshes and incidentals, say DISTRICT OF MOKA. Description of works rei^ui.'ed. Marsh reijuiring draining about 2 miles of drain A series of marshes re([uiring draining on about 2 iniles Marshy streams in the hamlet to be cleared of vegeta- tion ... Two marshy streams requiring clearing and trimming on a length of about 2 miles Three marshy streams requiring clearing and trim- ming on a length of about 2 miles... Large marsh to be drained ... Probable cost. Rs. 4.000 2,500 4,000 3,000 5,200 4,850 3,000 6,300 17,150 2,800 7,200 60,000 Probable cost. Rs. 5,000 5,000 1,000 5,000 5.000 5,000 26,000 I70 No. DISTRICT OF GRAND PORT Rose Belle Section IMace, I >e-rrlplion of works requiiLil. 1 M;uc Chicose... 2 Rose Belle 3 Xouvelle France stream 4 Balisson stream 5 Ruisseau Sec and Trilnitary 6 Eau Blcue stream 7 New Grove ... 8 River Tal^ac ... 9 Bonne Source 10 L'Escalier 11 Carreau Esnouf 12 Rviisseau Copeau Drainint; of marsh into Ruisseau Tranquille Marsh on Rose Belle estate to be cleared .. Clearing and improving on about 2 miles .. I 2.L No. 500 feel DISTRICT OF GRAND PORT Mahebourg Section^. l-'laco. Description of works required. 1 Mahebourg 2 Riviere des Creoles 3 Riviere La Chaux. 4 Riviere des Delices 5 Generallv Marsh to be filled u]) ... Clearing and improving on I mile Clearing and improving sources ol streams in the neighbourhood of the St. Hubert. Cent Gaulettes. Bel Air. Anse Jonchee. following localities : — Le Vallon. Beau Vallon Mon Desert. Virginia. 1.000 1,000 5,000 5,000 6,300 5.000 2,500 6,300 1,300 2,500 5,000 500 41,400 ]'rol.al;le cost. Rs. 1,000 2.500 2.500 2,500 8,000 16,500 No. Place. DISTRICT OF SAVANNE. ] Icscripliuu uf works required. 1 Camp Rabaud Hamlet 2 Si. Avolt estate Camp 3 Biilannia 4 l\i\iere des Angvulles \illage ... ' ... 5 Surinam Handel 6 7 Souillac Milage 8 Riambel Hamlet 9 Ste. Marie Hamlel ... 10 Beau Cham ]) estate Camp 11 Bel Ombre l-'.slate Camp 12 St. Martin Hamlet ... 13 I 'el it Caj) Hamlet 14 Do. 15 St. Aubin l-"state Camp 16 District generally Clearing of marsh Clearing and improving stream (Ri\-. Dragon' on 1,000 feel ... Clearing and impro\ing stream (Ri\-. Dragon) on 1,000 feet Clearing and improving River on 2,500 feet Clearing small marsh Clearing and improving Riviere la .Savannc on 10,000 feet Clearing and improving streams Ruisseau MiU'liell and olhers on 2,000 feet ... Drying small marshes Clearing and improving river on 2,000 feet Clearing and improving river on i.ooo feet Draining small marshes Marsh to be cleared near Cemetery Clearing and improving Choisy river on 1,000 feet Clearing marshes Clearing and imjiroving of streams on 2,000 feel ... Add for other parts I'roLable cost. Rs. 500 500 500 1.500 500 500 1.500 1,000 1.000 500 1,500 4.000 500 2,000 1,000 8.000 25,000 171 DISTRICT OF BLACK RIVER. No Place. 1 Albion 2 Gros Cailloux 3 Mouna 4 La Ferine 5 Flic en Flactj 6 Clarens 7 Tamaiin 8 Wolniar 9 10 11 Yemen ... Black Ri\er ... District LrcncralK' Description of works required. Draining of Marsh Ditto Ditto Ditto C'learing and inipri.iving marsh Draining of marshes ... Ini|iroving of marsh, as it may not he draineil nn accnunt of water riglits A large marshy district covering hundreds of acres. It seems hardly worth while to spend a lot of money for a \er\- thinly i>o]iulated ]ilace. .Might cost Draining small marshes I )raining a small marsh Draining other small marsh)' lands distrihuted over the district ... ProbaMe cost. 4,000 1,500 3,000 5,000 2,000 1,000 5,030 30,000 1,000 1,000 10,000 63,500 172 TABLE I. GIVING POPULATION, DEATHS, AND DECLARED DEATHS FROM FEVER IN MAURITIUS FROM 1831 TO 1906. Years. Population. 1 'calls. De.-ith Rate per 1,000, Fever Deaths. Fever Death Rate 1 per 1,000. 1831 92.951 2,495 . 26-8 1832 93,038 2,917 31-3 — _ 1833 93,643 2,561 27-4 — — 1834 93,209 3,417 39-8 — — 1835 93,631 3,367 360 — — 1836 97,534 3,020 310 — — 1837 103,935 3.862 37-2 — — 1838 115,110 3,533 30-7 — .— 1839 114,989 4,483 39-0 — — 1840 115,476 3,464 30-0 — — Mean 101,361 3,311 32-9 — — 1841 114,380 4,750 41-5 _ 1842 112,242 4,760 42-4 — — 1843 144,137 4,993 34-6 — — 1844 149,564 8,737 58-4 — — 1845 156.967 6,198 39-5 — — 1846 162,170 5,305 32-7 — — 1847 162,535 4,764 29-3 — — 1848 166,529 4,403 26-4 — 1849 169,770 5,235 30-8 — — 1850 176,307 5,547 31-5 — — Mean 151,460 5,469 36-7 — — 1851 184.496 4,890 26-5 _. 1852 199,158 5,591 28-1 — — 1853 208,800 6,192 29-6 — — 1854 212,482 17,978 84-6 — — 1855 220,238 7,269 33-0 — 1856 223,736 11,312 50-6 — — 1857 234,153 6,107 26-1 — — 1858 257,736 7,242 28-1 — — 1859 297.267 9,179 30-9 1860 309,901 9,805 31-6 — — Mean 234.797 8,556 36-9 — — 1861 324,287 6,854 31-1 __ 1862 330,575 13,719 41-5 — — 1863 335.310 11,566 34-8 — — 1864 341,392 11,649 34-1 5,789 17-4 1865 360,337 12.042 33-4 5,181 14-8 1866 365,051 11,702 32-1 4,913 14-0 1867 332,968 40,114 120-5 31,920 99-5 1868 324,370 18,403 56-7 10.923 34-9 1869 322,892 11,295 35-0 6,330 20-6 1870 328,604 7,423 22-6 3,329 10-6 Mean 336,579 14,476 44-1 9,769 30-3 173 TABLE \.--continued. Years. PopiilatiDii. J )eaths. Death Rate per i,ooo. Fever Deaths. Fever Death Rate per looo. 1871 319,470 8,171 25-6 3,578 Ill 1872 325,960 8,745 26-8 4,235 - 12-8 • 1873 332,476 11,210 33-7 5,031 . . .15-1 1874 339,806 10,019 29-5 4,024 11-8 1875 345,037 8,584 24-9 4,061 11-7 1876 346,390 9,525 27-5 4,845 . 14-0 1877 349,060 10,335 29-6 5,787 16-6 1878 355,058 9,649 27-2 5,144 14-5 1879 357,774 11,485 321 5,303 14-8 1880 360,328 10,143 28-1 5,173 14-3 Mean 243,135 9,787 28-5 4,718 13-7 1881 359,419 10,746 29-9 5,826 16-2 . 1882 359,322 12,563 35-0 7,483 20-8 1883 360,221 12,770 35-4 6,741 18-7 1884 368,813 11,247 30-5 6,103 16-5 1885 367,288 12,352 33-6 7,423 20-2 1886 368,145 10,624 28-9 5,839 15-8 1887 368,163 12,690 34-5 7.690 20-8 1888 369,302 11,193 30-3 6,110 16-5 1889 372,664 12,567 33-7 7,338 19-6 1890 370,624 12,781 34-5 7,004 18-8 Mean 366,396 11,953 32-6 6,758 18-4 1891 373,985 10,080 27-2 5,003 13-3 1892 374,079 13,055 38-4 5,598 14-9 1893 371,798 15,307 40-9 6,032 16-2 1894 376,219 10,792 29-0 5,655 14-9 1895 378,041 13,958 37-1 7,509 19-8 1896 374,942 15,843 41-9 8,181 21-8 1897 377,856 11,066 29-5 5,890 15-5 1898 378,872 12,064 31-9 6,507 17-1 1899 379,659 13,222 34-8 4,576 12-0 1900 389,897 13,691 34-8 4,844 12-4 Mean 377,535 12,908 34-5 5,980 15-8 1901 380,212 14,971 40-3 5,612 14-7 1902 383,410 12,716 34-0 4,456 16-6 1903 382,483 15,034 39-9 5,840 15-2 1904 387,395 12,064 32-2 4,333 11-1 1905 386,128 15,379 40-6 6,764 17-5 1906 383,206 15,118 40-0 5,827 15-2 Mean 383,606 14,214 360 5,472 14-2 174 TABLE II. STATEMENT SHOWING THE DEATHS FROM MALARIA AND FROM ALL CAUSES FOR THE YEARS 1896 1906. Districts. 1896. 1S97. j i8y8. 1S99. I goo. 601 1901, Port Louis... Malaria 1,565 1,111 1.394 789 802 All causes ... 3,184 2,262 2,699 2.836 1.982 3,002 PaniplL-moiisses Malaria 1,302 688 871 616 691 916 -Ml causes ... 1,966 1,110 1,282 1,319 L346 1,626 Kiv. (Ill l\am]).irt ... Malaria 598 308 378 241 219 299 All causes ... 1.042 580 674 629 722 839 I'Licq Malaria 1,309 982 1.153 1.002 1.112 1.000 All causes . . 2,065 1.572 1.855 1,670 1,961 1,759 Chand Port Malaria 1,007 915 691 625 690 823 All causes ... 2,234 1,702 1,508 1,492 1,633 1,751 Savannc Malaria 592 491 324 374 437 524 All causes . . . 1,299 974 479 969 992 1,231 Plaines WilliL-iiis ... Malaria 1,012 783 944 346 384 351 All causes .. 2,292 1,644 1,894 1,810 2,201 2,124 Muka Malaria 393 349 428 231 296 453 ^\.ll causes ... 1,197 787 943 915 1,054 1.142 Plack River Malaria 403 263 324 352 416 442 .Ml causes ... 564 435 460 508 607 685 T)istri(;ts. Port Louis... Pampleniousscs Kiv. ) 102 20 8 2 5 5| 1 355 12 60-0 4-4 — — 24-5 — 3,110 1.615 504 636 1.495 48-0 3-25 Savanne Beau Chaniji 777 125 505 41-9 Ulco 49 27 19 4 1 3 8 29-6 2-4 Plaine Magnien R.C. 250 104 62 44 12 4 2 18 29-0 20 Mare d' Albert 500 125 95 75 9 7 4 20 21-1 20 Noiivelle France 1,500 „ 37 35 1 1 2 5-4 1-2 PlainelMagnienGovernment 250 ,, 61 33 2 14 12 28 45-9 3-8 iVIahebourg Boys' Govern ,, 119 78 16 lb 10 41 34-b 2-6 ment. Mahebourg Girls' Govern- ,, ,, 73 bl 4 12 6 22 30-1 2-6 ment. Mahebourg Girls' R.C. ... 80 66 2 10 2 14 17-b 1-9 ,, Boys' Aided ... 47 25 6 10 6 22 46-8 6-6 New Cirove R.C. ... 930 68 54 2 3 9 14 20-6 2-3 ? Totai ? ,, 40 18 2 5 7 4 16 88-9 bS — 1,152 813 144 116 79 339 29-4 2-30 Savanne ... Souillac Convent, Aided ... , Masson 1 66 37 11 10 8 ' 29 43-9 3-1 ,, Government — 1 86 58 8 12 8 28 32-7 2-6 Surinam Aided ? — 58 29 4 12 13 29 50-0 3-9 Chemin Grenier, Govern- ? — 79 62 5 8 4 17 21-5 2-0 ment. Grand Bois ' „ — 41 i 40 1 : 1 2-4 1-0 Bale du Cap 6 — 59 21 9 8 21 38 67-4 4-8 Riviere des Anguilles Totai 400 Ross, Fowler — 60 53 b 1 1 7 11-7 1-4 — 449 1 300 43 : 51 55 149 33-2 2-74 Black Tamarin Bay Masson 25 17 1 7 4 5 ! 16 94-1 5-3 River Petite Riviere 250 55 29 11 10 7 1 18 62T 3-2 Cazela Government 350 32 19 5 9 3 2 14 73-7 3-6 Case Noyale Totai )) 31 1 11 3 1 4 3 1 8 72-7 1 3-4 — 76 20 30 17 9 56 173-7 ; i 3-85 Moka Cote d'Or Aided ... St. Pierre Convent Camp Saury R.C. ,, Ch. Eng. Moka Government Total 1,200 , Castel 35 35 33 1 1 31 31 29 2 41 41 34 6 1 61 61 45 13 2 1 95 95 68 19 41 4 8 4 5 263 263 209 2 5-7 2 6-4 7 17-1 16 26-2 27 284 54 20-5 1 1-2 1-1 1-4 1-7 1-9 1-61 i8o TABLE IV.— B {coiitimied). = Spleens "J District. i School. 1 Examiner. o I ' 3 6 9 Total with Spleen. Spleen Rait T. o u > V\ .AINES Brown Sequard St. Ciue- 1 1,800 1 Castel 181 181 174 1 2 4 7 3-8 1-2 VVlI.HEMS (I) pipe. Girls' R.C., Curepipe 151 151 146 4 1 5 3-3 IT Boys' ,, „ „ 130 130 123 3 3 1 7 5-4 1-2 Girls' Government, Cure- ,, ,, 125 125 123 2 2 1-6 10 (2) pipe. Curepipe Road Aided Total Camp Fouqueraux S.P.Ci. 1,450 ,, 71 71 68 3 3 4-2 IT 658 658 634 13 6 5 24 3-6 1T5 23 23 22 1 1 4-3 IT (3) ,, ,, Government Total Camp Mapou, Vacoas Glen Park Aided ... 1,400 )) 25 25 22 3 3 12-0 1-9 48 48 44 1 3 4 8-3 1-54 31 80 31 80 29 73 1 5 2 1 2 6-4 7 8-7 1-3 1-2 La Caverne Aided ,, „ 87 87 84 2 1 3 3-4 11 (4) Vacoas Road Total Phoenix Aided 141 339 141 134 3 3 1 7 4-9 1-2 339 320 11 6 2 19 5-6 1-20 39 39 34 3 2 5 12-8 1-4 St. Paul's Convent Ross, Eowler 109 44 30 7 4 3 14 31-9 2-8 (5) Phcenix (Police Station) ... Total Quatre Bornes Government 11 1,050 Castel 33 33 17 6 2 8 16 48-4 3-6 — 116 81 16 8 11 55 301 2-38 91 91 72 8 6 5 19 20-8 1'9 Belle Rose Avenue ,, 55 55 50 5 5 91 1-2 (6) „ Convent Total Rose Hill, Lalj.s. St. 950 40 40 39 1 1 2-5 IT 186 186 161 13 7 5 25 13-4 1-54 65 65 62 3 3 4-6 IT Edward VII. St. ^, ,, 55 55 54 1 1 1-8 TO ,, Ch. Eng. Aided „ 70 70 66 3 1 4 57 1-2 , , M a h m e d a n ,, 98 98 97 1 1 10 TO Aided. Rose Hill Government ... 75 75 72 2 1 3 40 1-2 „ St. I'nfant Jesus 166 166 156 7 ^ 10 60 1-2 (7) K.C. Aided ... Total Beau Bassin Ch. Eng. >> ICO 100 96 3 1 4 4-0 IT 629 34 629 603 20 5 1 26 4-1 112 750 34 33 1 1 2-9 IT ,, Convent Ch. 53 58 54 3 1 4 6-9 1-2 ,, Guslav Colin St. 72 72 64 5 1 2 8 11-1 1-4 ,, Girls' and Bo)-s' Total TOT.\L » 105 105 100 5 5 1 4-7 IT 269 269 251 14 1 3 18 6-7 151 6-7 1-22 2.245 2,094 88 33 30 1-26 i8i TABLE IV. C. SHOWING THE SPLEEN RATES OF CHILDREN EXAMINED IN VARIOUS LOCALITIES, 1907-8 section 20;. Spleens. c . rt g District. Locality, <'*" E.\aminer .— £ I 3 6 9 Total with •3 s >'3. 1 i "^ 61 59 48 38 spleen. 145 Pample- Terre Rouge School and 100 Milne. 206 66-5 4-2? MOtJSSES. Village. Pamplemousses School and 200 186 58 18 49 6I; 128 68-8 i 5-1 Village. Calebasses Milage 200 116 22 26 29; 39, 94 810 54 Belle Vue Harel Estate 350 100 88 10 2| 12 120 1-3 Long Mountain School and 500 194 82 45 34i 33' 112 57-7 37 Riviere du Village. Poudre d'Or School and 50 150 39 34 32 45' 111 74 4-9 Rem PART. Village. Riv. du Rempart School and 150 208 115 32| 37 24 93 44-7 3-1 Village. L'Esperance Estate ... 200 174 125 28 12 9 49 281 ! 2-1 Beau Scjour Estate ... 400 i „ 100 77 8 8 7! 23 230 [ 2-1 Mont Piton Camp 650 100 65 18 14 3i 35 35 2-3 Flacq. Trou d'Eau Douce School and 50 185 67 49 42 27| 118 63-8 3-8 Village. Post of Flacq School and 50 162 20 31 39 72' 142 87-6 6-1 Village. Constance d'.\. Estate 100 166 7 41 181100 159 95-7 ' 7-5 Beau Champ Estate ... 100 „ 202 33 49: 50 70 169 83-7 5-5 Centre of Flacq School and 150 237 25 33 86| 93, 212 894 6-2 Village. Riviere Seche School and 200 202 21 67 46 68 181 89-6 5-8 Village. Olivia Estate 350 113 17 25 36 35 96 84-9 4-7 St. Julien Village 450 150 126 10 5 9 24 16-0 1-8 Rich P\uk1 Estate 600 151 122 15 6 8 29 19-2 1-8 Seliastopol \'illagc 650 150 117 20; 7 6 33 220 1-8 MOKA. Pailles Village 200 162 29 341 46 53l 133 82 1 6-0 Montagne Blanche School and 900 150 137 8 4 1 13 8 6 1-3 Village. .Sans Souci Estate 950 200 178 17 2 3 22 110 1-2 Quartier Militaire Village 1,350 )) 143 3,907 129 1,768 8 677 5 657 ll 14 9-7 1-3 805 2,139 54-7 3-83 Grand Port. Pl. Wilhems. Black River. Nmivelle France Milage Tintaniaree ('r) Flic-en-Flac Village ... Bambous School Anna Estate ... Carried forward 1,500 Massun 61 60 p ; 47 45 40 9 400 ' „ 73 32 p .39 22 260 168 1 10 1 1 6 15 10 15, 14 12 7 6 1 2 31 41 17 leii-i 4-3 ! 1-2 77-5 ! 5-2 56-1 1 3-8 43-6 : 2-9 29 36' 271 92 l82 I'ABLE IV.— C {contiinu'd). District. Locality. Examiner. £"2 .2'S Spleens. , 369 Total with 1 ^i- 29 36 spleen.; Brought forward 260 168 27 1 92 i Pi,. WlLHEMS. Phcenix, collected children ... 1,350 Ross, 27- Fowler 12-07. 163 74 37 46' 6 1 i 89 55-3 3-16 Do. House to House in 1,350 Ross, Fowler 339 98 104 82 55 241 71-1 4-12 1 19 Houses. Feb 1908. Highlands Estate 1,400 Ross. Fowler 50 47 10 2 3 6-0 1-36 7-12-07. Phoenix along Curepipe Road 1,450 38 36 2 2 52 1-10 Le Reduit — Ross 58 55 111 3 5-1 1-26 ToKi Louis. Men's Training Government School. Ross, Fowler 169 102 43 17 7 67 39-6 2-34 S.WANNE. St. Felix Estate 400 30 24 3 1 2 6 200 1-9 Tampi.e- Beau Plan Estate 200 )> 26 4 16 5 1 22 1 84-6 3-5 MOUSSES. 1,133 £08 236188101 525 46-3 2-96 MlsCELI-ANEOUS Curepijie 1,800 107 106 1 0-9 Curepipe to Phienix Road ... 1,700- 1,400 130 124 — — — 6 4-6 La Caverne 1,350 104 104 — — — — — Henrietta 1,600 ,, 62 59 — _ — 3 4-8 — Solferino 1,200 1 ,, 51 43 — 1 8 15-7 La Louise 1,100 63 51 — — 12 19-0 — West of Rose Hill 700 56 30 — — — 6 16-6 — Moka 1,200 •)•> 62 59 — — — 3 4-8 — Camp Fouquereaux ... ! 1,450 26 26 — — — — — Petite Riviere 200 62 23 — — — 39 62-4 — Tranquebar 50: ?j 32 — — — 32 1000 Port Louis 41 19 — — — 22 53-6 Road to Arsenal 100 " 109 72 — — — 37 169 33-9 — 885 716 — 190 i83 TABLE IV.— D. SUMMARY OF SPLEEN RATES (section 20) 2 2 Spleens Total 2 jj j= ■< 1 3 6 9 '^^ ■■-■0. uw spleen. 's-.oi. <4 i86 PLAN OF VACOAS CAMP AND CLAIRFOND MARSHES. (For Addt'iidiiDi 2.) 1. The fractions (such as 3 '7), denote the ratio of the number of chiUh'en with enlarged spleen (3) to the total number examined (7). 2. The Roman numerals denote the houses referred to in Dr. de Chazal's re[)ort, as follows : — ■ - - House I. Affected January, 1906. II. )i August, „ III. „ November, 1906 IV. if December, „ V. » February, 1907. VI. 51 March, „ VII. )) April, MIL )' Servants in June, children in December. IX. )) September, 1907. X. „ December, ,, XL )) January „ XIl. )) February „ XTIT. to XWT. not affected by Ma'aria. H. w here rasi >>< rif I'.lrifl,- w.i tr>r fi'\ijr nrniirrpd House H*, case of Blackwater had moved in here from House HI. four weeks before he was attacked. 'i'he marshes are entered in black. I4A >*'■• . it 4.- ^-"' < #; / ^ 189 PHOTO. I.-Plateau of Plaincs Wilhen.. In.n, near Curei-ipe, looking norlh^vard. Thoto. 2.— Plateau of Plaines Wilhems from near Curepipe, looking westward. Cane fields. IpO \ I % ,.;i^- '--^'^' -'^ Photo. 3. — The Black River, near the Coast. By Maior Fowler. Photo. 4 — Portion of a Cane-Field. m Photo. 5. — The Bishop's House at Mok Photo. 6. — Labourdonnais House on Estate. 192 Photo. 7.— Middle-class Creole's tlouse at La Caverne. Photo. 8. — Shanty at Port Louis, made mostly of old tins. nor 193 Photo. 9. — Indian's IIousl-. By Miss Lane. V '■10^: ^^ ;i r- '.V, - , .,. Photo. 10. — Indian's House near Clairfond Marsh. 194 Photo, ii. — Moustiquiers at work in Marsh at Curepipe. Photo. 12. — Marsh in Wood at Phoenix. 195 Photo. I3.-Marsliy condition at Clairfon.l, made l.y a Cnservancy Road. Photo. 14 i4._Ornamental Pond in Gardens at Curepipe. Aloustiquier at work. IS 196 I'Horo. i5.-Anopheiine Breeding Breeding Pool in discharge from Factory, Esperance Estate. Photo. 16 .-Densely-Nvooded Ravine from Government House Gardens, Le Reduit. 15A 197 PHOTO. i7.-Anophelme Breeding Place in uncanalised part of La Paix Stream at Port Louis. By Major Fowler. 19^ Photo. iS.— Cartload of Bilbcrgia (breeding Stcgomyia) removed from a single house at (hiatre Bornes. Photo. 19.— Travellers' Palms at Mare-aux-Vacoas. 199 Photo. 20. — Tub containing pots filled \wtli i;un water and biLcdm'' ,^tt£v///j'ta. 200 Photo. 21.— Child with enormously enlarged spleen. Photo. 22.— Net used to estimate number of Anophelines given off by nine square yards of Clairfond Marsh. 20I Photo. 23. — Part of channel at Qairfond Marsh cleared by three men in one day. Photo. 24. — Rough canalisation of Latanier River, Port Louis. 102 Photo. 25. --Rough canalisation of Mesnil River, by Forest Department, at Rs.o-37 a runnintj foot, for Ijoth banks. RETURN BIOSCIENCE & NATURAL RESOURCES LIBRARY TO — ^- 2101 VALLEY LIFE SCIENCES BLDG. 642-2531 LOAN PERIOD 1 2 3 ' uNl, ^ONTH L„^^ ALL BOOKp^4/ m^ijA^D^^ 7 DAYS DUE AS STAMPED BELOW JAN '^ 1 IMMEDIATELV UNIVERSITY OF CAUFORNIA, BERKELEY FORM NO. DDO, 50m, 1 1/94 BERKELEY, CA 94720 (D647l8lU)4:7t> Berkeley CDSlba3t33D