GIFT OF The Problem of Rocky Mountain Spotted Fever BY ,VVi • n^^7 P. A. Surgeon W. C. Rucker United States Public Health and Marine-Hospital Service REPRINT FROM U/te MILrlTA^RY SVRGKON WASHINGTON. D. C. THE ASSOCIATION OF MILITARY SURGEONS 1911 The Problem of Rocky Mountain Spotted Fever BY P. A. Surgeon W. C. Rucker United States Public Health and Marine-Hospital Service REPRINT FROM ^he MILrlTARY SVRGEON WASHINGTON, D. C. THE ASSOCIATION OF MILITARY SURGEONS 1911 .A-^ V t^^ THE PROBLEM OF ROCKY MOUNTAIN SPOTTED FEVER.* By p. a. Surgeon W. C. Rucker, U. S. Public He;alth and Marinh-Hospital Service. HISTORY. FOR over a decade Rocky Mountain spotted fever has been a problem of great interest to the physician, the zoologist and the sanitarian. Its geographic limitation, seasonal prevalence, intimate association with wood-ticks and variation in severity in different localities, combine to make it one of the most interest- ing and intricate disease problems which has arisen in our genera- tion. It has a peculiar interest for us because apparently it i§ con- fined to the American continent. Some of the earlier investiga- tive work in this field was done by members of the Association of Military Surgeons of the United States, and it has therefore been considered appropriate to present a brief review of the progress in the study of the disease to the Association and to indicate the lines along which investigative and eradicative work should be carried in the future. Although the disease has been known in Idaho and Montana since 1873, the first specific reference to it in literature is to be found in the report of the Surgeon General of the Army for the fiscal year ending June 30, 1896 (76). It is there stated that "the Surgeonf at Boise Barracks referred in one of his monthly re- ports to the prevalence of spotted fever in the civil settlements in the neighborhood of the post. On being requested to give fuller particulars concerning this fever, he stated that as he had not seen any of the cases that occurred he had called upon his medi- cal friends in civil life for information," These gentlemen (Drs. •Read by title at the 20th Annual Meeting. tThen Captain, now Lt. Col., Deputy Surg. Gen'l, Rtd., Marshall W. Wood, M. C, U. S. A. 244501 4 P. A. SURGEON W. C. RUCKER. C. L. Sweet, W. D. Springer, R. M. Fairchild, L. C. Bowers, J. K. Dubois, D. W. Figgins and H. Zipf ) responded promptly and their reports constitute the first published accounts of Rocky Mountain spotted fever as a disease entity. It was not until 1899, however, when Dr. E. E. Maxey of Boise, Idaho, read a paper entitled, "Some observations on the so-called spotted fever of Idaho," (32) before the Oregon State Medical Society, that the disease began to attract any wide-spread atten- tion. This lucid paper expresses the opinion that spotted fever is a specific disease and gives an accurate description of its clini- cal manifestations. In 1902, the then newly organized Montana State Board of Health selected for its first task the careful investigation of the disease, securing for this purpose the services of Drs. L. B. Wil- son and W. M. Chowning of the University of Minnesota. Their work, which was done in the Bitter Root Valley of Montana, con- stitutes the first serious laboratory study of the disease (12, 72, 72)y 74. 75). afid in a paper written July i, 1902, (69) they sug-' gested the role of the ground squirrel (Citellus columbianus) and the tick {Dermacentor andersoni) as host and vehicle of transmission, respectively. In the same year Surgeon J. O. Cobb of the U. S. Public Health and Marine-Hospital Service, visited the Bitter Root Valley and wrote a description of the disease (13). Subsequent investigations have been made by Ashburn (5, 6, 7), Craig (7, 16), and Keiffer (26), of the Army; Anderson (i, 2, 3), Stiles (64-70, inclusive), Francis, King {2y), and McClintic of the Public Health and Marine-Hospital Service; and by sev- eral others, the most noteworthy among whom are the martyred Ricketts (41-54, inclusive), and his associates. GEOGRAPHIC DISTRIBUTION. The disease has been reported from nearly all the states in the Rocky Mountain group, California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington and Wyoming each having foci. Cases have also been reported from the District of Alaska. The geographic distribution of the disease is shown as follows in tabular form : ROCKY MOUNTAIN SPOTTIW fliVUR. Geographic Distribution of Rocky Mountain Spotted Fever. State. Alaska . . California Colorado Idaho Montana Nevada . . . Oregon Utah Washington Wyoming . . Locality. Klondike . Calneva . . . Carbondale Rifle Valleys of the Weiser, Payette, Boise and Wood Rivers : North bank of the Snake River : Southwestern Idaho West side Bitter Root Valley. Phillipsburg, Clinton, Camas Prairie Rock Creek, Blackfoot, Rattlesnake and Lolo Valleys Bridger Livingston ■. Quinn River Valley Paradise Valley, Win- nemucca. Ft. McDer- mitt, Reno Burns Lakeview Merrill Cedar Valley, Fairfield, Cedarfort Heber City Moses Lakes, Douglas Co Thermopolis, Meyers- ville, Shoshone River. Crow Creek South Pass, Ft. Fetter- man, Ft. Steele, Chey- enne Cody, Meeteese Reporter. Gwinn (21). Snow.* Braden (56). Le Rosignol and Hotopp (56). Maxey (32). Wilson (72) and Chowning. Anderson (i). Stiles (64). Andersofi (2). McCullough (36). Gates (2, 66). Alton (64). Kendall (2). Robinson (56) lieary (19)". Steiner (56). Patterson (56). Noves (56). Wheritt (56). Smith (61). Gates (2, 66). Kieffer (26). Robinson (56). Bradbury (75). •Personal letter. 6 P. A. SURGEON IV. C. RUCKER. Data regarding the prevalence of Rocky Mountain spotted fever in the known infected IccaHties is very sparse except in Montana and Idaho. In the latter state, Dr. Edward K. Maxey of Boise, collected data on 380 cases which occurred during 1908. The following table shows the occurrence of the disease in the Bitter Root Valley from 1885 to 191 1, inclusive, representing data collected by Wilson and Chowning, Anderson, Stiles and Mc- Clintic: Human Cases of Rocky Mountain Sj>otted Fever in the Bitter Root Valley of Montana. Year. Cases. Deaths. Mortality. Year. Cases. Deaths. Mortality. Per Cent. Fer Cent 1885 1 1 100 1899 _, 23 14 60.8 1886 1 1 100 1900 — 12 9 75 1887 1901 -, 14 10 71.4 1888 3 1 33.3 1902 _, 21 15 71.4 1889 3 3 100 1903 -, 14 9 64.2 1890 1 1 100 1904 -, 11 9 81.8 1891 6 4 - 66.6 1905 — 1892 3 1 33.3 1906 __ 1893 4 2 50 1907 __ --- ---- 1894 1908 — 5~" 1895 3 3 100 1909 __ 28 13 46.4 1896 6 6 100 1910 — 19 14 73.6 1897 6 5 83.3 1911 _, 16 6 37.5 1898 3 3 66.6 (*) i 2 50 •Year not definitely known. It might be well to point out at this time the necessity for the careful collection of data regarding the occurrence of cases in the various infected states. Rocky Mountain spotted fever certainly should be put on the list of reportable diseases. SYMPTOMS IN MAN. Passing now to the consideration of the clinical aspects of the disease in man, Maxey's definition of the disease may be modified to read. Rocky Mountain spotted fever is an acute, endemic, febrile disease, occurring chiefly during the summer months, transmitted by the bite of the tick, and characterized clinically by a continuous moderately high fever, severe arthritic and mus- cular pains, and a profuse petechial or purpuric eruption in the skin, appearing first on the ankles, wrists, and forehead, but rap- idly spreading to all parts of the body. After an incubation period varying from three to ten days, ROCKY MOUNTAIN SPOTTED FEVER. 7 usually seven, during which the patient may feel indisposed and complain of ill-defined sensations of cold, nausea and weariness, there is a frank chill. If seen at that time, the patient will gen- erally complain of pain and soreness in the muscles, bones and joints, especially in the lower lumbar region. Severe occipital headache and photophobia are frequent symptoms and the face may appear flushed and swollen. Epistaxis commonly occurs and constipation is the rule. The severity of the symptoms varies in individual cases and is less severe in Idaho than in Montana. Upon examination the face is apt to be flushed, and the con- junctivae congested and yellowish. The tongue is covered cen- trally with a heavy, white coat while its tip and edges are bright red. A slight bronchitis may exist and the urine is scanty and may contain small amounts of albumin and a few casts. Prior co the initial chill there may be a little afternoon fever, but with the chill there is an abrupt elevation of temperature and on the suc- cessive days there is an evening rise with slight morning remis- sions. At any time from the eighth to the twelfth day, usually the tenth, the fastigium is reached when, if the patient is to re- cover, a fall by lysis takes place, the curve reaching subnormal from the fourteenth to the eighteenth day and remaining so for three or four days. In certain of those cases which do not reco/er there is a continuous fever of 105° F. or higher. In other cases there is a sharp drop in the temperature curve followed by a sud- den rise just before death. The pulse is very rapid and apt to be thready. There is a pro- gressive decrease in tlie erythrocytes and haemaglobin. A leu- cocytosis with considerable increase in the large mono-nuclears occurs. The respiration rate is increased in proportion to the pulse. An initial bronchitis is not uncommon and hypostatic pneumonia sometimes occurs. Usually on the third day (sometimes on the fourth) the erup- tion appears on the wrists and ankles, first as a macular roseola, which as it spreads to the arms, legs, forehead, back, chest and abdomen, in the order named, becomes papular and may terminate in indefinate blotches or petechiae which may become large ecchymotic spots. In severe cases even the palms, soles and scalp may be invaded. From twelve to forty-eight hours are re- 8 P. A. SURGEON W. C. RUCKER. quired for the rash to reach the maximum. The macules vary in size from a pinpoint to a split-pea and are bright red except when the case is unusually severe when they are dark purple. Not infrequently they assume this color after death. It was this sign which caused the earlier cases to be called "the blue disease" or "black measles." The macules disappear readily on pressure rapidly to return — the papules do not disappear on pressure until the patient is progressing to recovery. With the fall in the fever, the eruption begins to fade, but for a considerable time after re- covery it may reappear as a subcuticular mottling after free perspiration or a warm bath. Cases have been reported in which there was no exanthem. Late in convalescence there is a gen- eralized desquamation. Gangrene of the ears, fauces, fingers or toes, scrotum, penis, or entire pudenda may occur as distressing sequelae. Haematogenous jaundice usually occurs and in addi- tion the face may have a bloated appearance erasing the lines of expression and giving it a stupid look. The teeth are covered with sordes early and the tongue is coated throughout the disease. This coating is at first white, but later it becomes light yellow and finally dirty brown. The mouth is dry and cracked. Constipation, sometimes extreme, ex- ists throughout the disease. Initial nausea which may extend throughout the disease is not uncommon. There is splenic and hepatic enlargement. The urine is high colored, acid and reduced in amount. Albu- min and granular, hyaline and epithelial casts are found in about fifty per cent of the cases. Haemaglobinuria almost never occurs. The mind is usually clear throughout the disease. During the period of invasion there may be restlessness and insomnia owing to the attendant pain in the bones and muscles. Later this is ab- sent. Kernig's sign is not found. Ocular symptoms are very rare. SYMPTOMS IN ANIMALS. The reactions which occur when laboratory animals are inocu- lated with the disease are fairly constant. Guinea pigs when given 0.5 cc to 5.0 cc of defibrinated infected blood, serum or washed corpuscles, subcutaneously or intra-peritoneally present a rise of temperature after an incubation period varying from two to five days. From the fifth to the seventh day the temperature ROCKY MOUNTAIN SPOTTED FEVER. 9 may reach 107.6° F. Coincident with the fastigium, the scrotum and testicles become swollen and oedematous and subsequently the overlying skin of the pudenda becomes the seat of hypodermic haemorrhages of varying size and outline. Vulvar changes occur in female guinea pigs, but are less constant. The soles of the fe^t and the ears are red and congested, and if the animal be depilated, reddish macules may be observed on the dorsal and lateral aspects of the body. Emaciation is rapid, and death usually occurs from the seventh to the eleventh day. Recovery, when it takes place, is gradual and may be accompanied with scrotal sloughing, followed by deforming cicatrix formation. There is desquamation of the soles of the feet and the ears become dry and brittle, subsequently dropping off leaving a short thickened, irregular stump. The animal is emaciated and may not regain its normal weight for several weeks. When the disease is transmitted by ticks the signs are much the same, except that there may be areas of necrosis and patchy alopecia at the points where the ticks attached. In monkeys {Macacus rhesus), the disease produces cyanosis of the face and ears, a skin eruption varying from an erythema to a macular and petechial marking distributed over the external aspects of the arms, legs, buttocks and back. The scrotum a: penis are enlarged and haemorrhagic. The rabbit (Lepus sp.) is mildly susceptible to the virus, but in far less severe form than in guinea pigs and monkeys. After an incubation period varying from three to six days, the temperature reaches 104° F. and falls by lysis. Aside from congestion of the scrotum no marked anatomical changes have been recorded. The susceptibility of the various domestic animals and the mammals of the infected zone will be discussed elsewhere. PROGNOSIS. In the Idaho cases, the prognosis seems to be very favorable, as a rule the mortality averaging less than 4%. The disease is far more lethal in Montana and there the mortality averages close to 75%, although in some years it has fallen as low as 33.3%. Death . may occur as early as the third or as late as the eighteenth day of the disease. In general, if the patient survive the tenth day, the 10 p. A. SURGEON W. C. RUCKER. prognosis is far more favorable. Continuously high fever or a sudden drop in temperature are grave signs as is also delirium or loss of consciousness. GROSS PATHOLOGY. The pathological changes are not extreme but they are fairly characteristic. In man, rigor mortis usually appears early and is intense. The skin changes observed at necropsy are practically the same as those seen ante-mortem and include the small wounds the result of tick bites. Icterus is constant and cutaneous haemorrhages of varying sizes and shape are usually seen. In the Idaho cases, gangrene of the fauces, tonsils, and palate, and of the scrotum, penis, and vulva have been noted. Aside from occa- sional hypostatic congestion and a rare pneumonia, the respiratory apparatus is usually normal. Epicardial haemorrhages over the ventricles were constantly found in Anderson's cases (2). The heart muscle is flabby, soft and pale. The right heart is usually full of firmly coagulated blood while the left heart is contracted and empty. The spleen is usually enlarged to three or four times its normal weight, is dark purple, soft and very friable. The liver is enlarged and shows cloudy swelling and fatty degeneration. The pancreas is about twice its normal weight. The intestines may show submucous haemorrhages. Le Count (28) notes the enlargement of the superficial and visceral lymph glands. The kidneys are usually enlarged and present subcapsular and pelvic haemorrhages. The other abdominal viscera are not markedly affected. The changes in the nervous system are not constant enough to be of value in the post-mortem diagnosis of the disease. In guinea pigs, the pathological changes noted include coagula- tion necrosis about the site of inoculation; enlargement of the superficial lymph glands with central haemorrhages and degenera- tion; splenic and hepatic changes similar to those observed in man; enlargement of the supra-renal bodies; localized haemor- rhages with necrosis of the pudenda ; and gangrenous changes of the ears. The lesions in monkeys are practically identical with those observed in man. MICROSCOPIC PATHOLOGY. The microscopic "changes are of two sorts, those connected ROCKY MOUNTAIN SPOTTED FEVER. 11 with the occlusions of vessels and the more diffuse lesions affect- ing entire groups of organs. The diffuse changes are hyperplasia of lymphoid tissues and cloudy swelling and acute fatty changes in organs commonly the seat of such lesions in acute infectious diseases. The focal lesions are more varied in their nature since they include not only the processes leading up to the occlusion of vessels, but the results of such obstructions, necrosis in different degrees and the haemorrhages responsible for so many of the clinical and gross anatomic features of the disease as well as for the name 'spotted fever' (28)." The minute changes have been made the subject of a careful study by Le Count (28) to whose article the reader is referred. TREATMENT. Many methods of treatment have been advised and employed in the attempt to cure this disease. They run the gamut of the pharmacopoea from sage tea to quinine and they have returned to that tacit admission of ignorance "good nursing and symptomatic medication." Ricketts (52, 54), has produced a protecti\e (and if given very early, and in large doses, curative) serum which Heinemann and Moore (22) have attempted to concentrate. The number of cases in which it has been used is too small to judge of its efficacy. Dr. Karl Kellogg of Stevensville, Montana, and Dr. J. Wilson Reed of Victor, Montana, have each used sodium caccodylate with apparent success in a single case, but until we are better informed as to the etiology of the disease all attempts at its cure must be empirical and groping. ETIOLOGY. When we attempt the consideration of the etiology of this disease we are in a certain measure entering a terra incognita. As noted by Maxey (32), in his original paper, spotted fever is a "place" disease, being definitely limited to a certain locality, for example, to a single side of a valley. It is also rather sharply limited to a definite season of the year, usually to the months of March, April, May, June and July. It attacks all ages and both sexes, although the greater number of cases have occurred in males between 30 and 40 years of age. Persons whose occupa- tions take them into the wooded foothills seem more liable to the disease, therefore the bulk of the cases have occurred in lumber- ]2 7'. A. SURGEON W. C. RUCKER, men, miners, prospectors, ranchers, and sheepherders, and bridge builders, carpenters, civil engineers and others concerned in rail- road construction work. It is apparently non-contagious, more than a single case rarely occurring in a given household at the same time. It has been impossible to incriminate water or food of any kind as the vehicles of infection, although when Maxey presented his first paper he suggested that the drinking of snow water might be the means of receiving the disease. THE TICK HOST. Wilson and Chowning in their original report (72) suggested the hypothesis that the wood-tick {Dermacentor andersoni) acted as the transmitting agent and offered in support of this theory several facts which may be thus summarized : 1. The appearance of the disease is coincident with the period of ac- tivity of the wood-tick. 2. The disappearance of the disease is coincident with the disappear- ance of the wood-tick. 3. The limitation of the disease in a certain locality suggests the con- veyance of the germ to man by a temporary parasite "traveling slowly and not widely and which is not carried far by the wind. The tick answers this description." 4. The great bulk of patien-ts give a history of having been bitten by ticks prior to their illness. 5. Mosquitoes may be eliminated from the problem because their ap- pearance and disappearance does not coincide with that of spotted fever; because of their lack of geographic limitation; and because they would be more apt to bite and thus infect a greater number in a given family. Bedbugs and fleas are omnipresent and perenial — spotted fever is not. Cobb (13), Anderson (i, 2), Westbrook (56), and R. W. Smith (56), coincided in this view, but Stiles (64), was "unable to confirm this hypothesis." Ashburn (5) reached the same con- clusions as Stiles. In 1906, King (27) succeeded in transmitting the disease from one guinea pig to another guinea pig by an adult male tick and Ricketts (41-46) was able to similarly transfer the infection by an adult female tick. The following year, 1907, Rick- etts (45) demonstrated that infected ticks exist in nature on the west side of the Bitter Root Valley of Montana and by their bites he reproduced the disease in guinea pigs. He further showed that the larvae and the nymphs, and both adult male and female ticks ROCKY MOUNTAIN SPOTTED PEVER. 13 infected by feeding on an infected animal may transmit the disease to normal susceptible animals : that larvae and nymphs may acquire the disease in a similar manner and that they are capable of transmitting it in their subsequent stages of develop- ment: that infected females may transmit the disease to their young through their eggs : that the infection is generalized in the body of infected ticks : that the virus remains active in the body of the nymphal tick : that infected ticks are infective as long as they live and will bite. From the foregoing, it may be deduced that the tick is the disseminator of the causal agent of the disease in nature. As a final and clinching proof, McCalla (34) re- moved a tick from a man suffering with the disease, and with their consent, infected a man and a woman by its bite. Since it has been proven that the disease exists in ticks in na- ture, it is to be expected that the distribution of the disease is the same as the distribution of the dermacentor. This has been made the subject of a study by Bishop (9) and while Rocky Mountain spotted fever has not been reported from the entire life zone of this tick, with the exception of the cases which occurred in the Klondike, the disease has not been found outside the area which the tick infests. This includes the northern part of the Rocky Mountain region in the United States, and the river valleys and sagebrush plains to the west, the western corner of South Dakota, almost the entire states of Montana, Wyoming and Colorado, the northern portion of New Mexico, Utah and Nevada, all of the state of Idaho, the eastern half of Washington and Oregon, and the northeastern corner of California. It also occurs in southern British Columbia, and eastern Alberta. There has been more or less discussion regarding the taxonomy of this species, but that is a question for zoological nomenclatur- ists which need not be considered here, and it should be borne in mind that Maver (31) has transmitted the disease by three other species, Dermacentor marginatus (Utah), Amhlyomma Ameri- canum, Linnaeus, (Missouri) and Dermacentor variabilis, (Mass.). It may be of profit, however, to describe briefly the com- monest form {D. andersoni) and to outline its life history,* ♦The writing's of Stiles (68, 69) and Ricketts have been freely drawn upon in the preparation of this description. For a more technical con- sideration of the subject the reader should consult Bull. 62. U. S. Pul). Health and Mar. Hos. Serv., Hyg. Lab., 1910. 14 P. A. SURGEON IV. C. RUCKER. THE ANATOMY Ol-" TICKS. Ticks, superfamily Ixodoidea, order Acarina, class Arachnida, represent the giant mites. Anatomically a tick may be divided into a head, rostrum, or capitulum, and a body. The capitulum consists of a neck which connects it with the body ; a hard, usually quadrangular portion called the base, which presents two porose areas and supports the palpi, which are composed of four seg- ments, the hypostome, and elongated structure in symmetrical halves, which are covered with minute recurving teeth, and the mandibles or biting apparatus. The body is more or less ovoid in shape and varies greatly in form, color, outline and structure in the different species and at different periods of development. The body is divided for purposes of description into a dorsal sur- face, a ventral surface, and anterior, posterior, and lateral mar- gins. The dorsal surface presents a hard, chitinous plate, marked by two longitudinal grooves. This is called the scutum and is smaller in the female than in the male. The eyes are seen at each lateral margin of the scutum and on each side of the median line, near the third and fourth legs, are small, oval, chitinous structures called the dorso-submedian porose plates. Along the posterior margin of the body are the postero-marginal festoons, eleven in number. The ventral surface presents for examination the genital pore, situated between the coxae of the first three pairs of legi-; the anus, similarly situated in the median line but behind the pot;- terior pair of legs; and the stigmal plates placed laterally just be- liina tiie tourtli pair of legs. The anterior, posterior, and lateral margins vary in the different species. The legs are four in number on each side and each is seg.nented into a cova, trochanter, femur, patella, tibia, and tarsus. Both the dorsal and the ventral surfaces present grooves, pits, hairs and spines which are of value in distinguishing the various species.* THE DERMACENTOR ANDERSONI. The Dermacentor andersoni Stiles (1905), male is oval, narrov/ •For a description of tlie internal anatomy see CHRISTOPHERS, (S. R.) The anatomy and histology of ticks. Calcutta, 1906, . ROCKY MOUNTAIN SPOTTED VEVHR. 15 in front, broad behind, with scutum variegated brown and white. Anteriorly there is an elliptical area, called the pseudo- scutum, limited by a white border and possessing two lateral brown stripes, with a median brown stripe or spots between them. Behind this there are four brown stripes arranged in a curve, open anteriorly. Posterior to these there are usually five brown stripes, one central and two on each side. Elsewhere the whole dorsum is speckled with small brown dots. The eleven festoons of the pos- terior border are roughly quadrangular in outline and consist of a white area with one brown spot and small brown specks. On the ventral surface, it is noted that the first coxae arise by two roots, bidentate, while the others arise by a single spine. The fourth coxa is very large, being two or three times the size of the third. Opposite the second pair of legs is the genital aperature. The stigmal plates are somewhat comma shaped.* The non-engorged female is about the same size as the male, 5 by 2.5 millimetres. The body is oval and broader posteriorly than anteriorly. The scutum extends as far back as the third pair of legs and is marked like the corresponding portion of the scutum of the male. There is a dorsal marginal groove and three longi- tudinal grooves. Eleven festoons on the posterior margin. The genital aperature on the ventral surface is opposite the second coxa and from it the genital grooves run backward diverging lat- erally behind the fourth coxa and ending between the second and third external festoons. There is a short anomarginal groove. The replete female is about 16 by 10 millimetres and deep brown or slate color. LIFE HISTORY D. ANDERSONI. The adult male and female feed in common on various mam- mals and it is during this time that copulation and fertilization takes place. The female continues to feed for several days after fertilization until she has become a slate colored, swollen ovoid •See Stiles' "The taxonomic value of the microscopic structure of the stigmal plates in the tick genus Dermacentor." Bull. 62., U. S. Pub. Health and Mar. Hos. Serv., Hyg. Lab., 1906. 16 P. A. SURGEON IV. C. RUCKBR. body. This increase in size is due to the ingestion of blood from the host and the enlargement of the ovaries and beginning forma- tion of hundreds or even thousands of minute eggs. After com- plete engorgement, the female drops from the host and after a resting period of about two weeks begins oviposition. To accom- plish this the head is bent ventrally until the capitulum rests on the edge of the genital opening. At the same time there is protruded from beneath the scutum a delicate white gelatinous membrane which terminates in two delicate cones covered with an adhesive secretion. The extrusion of this membrane covers the head and as the two small sticky cones reach the genital orifice the egg is expelled on to them. The membrane is then withdrawn and the head extended, the egg resting on the front of the scutum. In this way an adherent mass of eggs gradually forms in front of the tick.* Unless observed closely it appears as though the eggs were being extruded from beneath the scutum. As this process continues the tick begins to shrivel and at the end of oviposition it dies. The number of eggs deposited varies from several hun- dred to three thousand. The length of time before the eggs begin to hatch depends on the surrounding temperature. In the summer months, it is from thirty to fifty days, but in the cold season it may be delayed for several months. From the egg appears the larval form of "seed- tick" stage. These are minute specks which are first pale and soft, and later become covered with a hard brown coating. They have six legs and are without genital and spiracular orifices. They are seen in nature in clumps on blades of grass or twigs where they wait with outstretched legs for passing mammals. Having attached themselves to a warm-blooded host they feed to engorge- ment in about six days. During this time the original bulk is in- creased many fold, reaching about the size of a head of a pin. The color, which depends on the character of the food taken, blood or serum, varies from light pink to dark brown. Having fed to sur- feitment, the tick drops off and lies dormant for about four weeks •See BRAUN, (M.), "The animal parasites of man." "Wm. Wood & Co., N. Y., 361. ROCKY MOUNTAIN SPOTTED FEVER. 17 prior to moulting. Here again the time varies, being as short as two weeks and as long as two months. Unless the larvae se- 2. See also Contrib. to Med. Science, Ricketts, Univ. Chicago Press, 191 1, .333-342. 49. Recent studies of Rocky Mountain spotted fever in Montana and Idaho. Med. Sentinel, Portland, Oreg., 1908, XVI, 668-697. (Dis- cussion 704-711.) 50. General report of an investigation of Rocky Mountain spotted fever, carried on during 1906 and 1907. Fourth Bien. Rep. St. Board of Health of Montana, Helena, 1908, 86-130. 51. A report of investigations carried on during the winter of 1907-8 and the spring and summer of 1908. Fourth Bien. Rep. St. Board of Health of Montana, Helena, 1908, 131-191. 52. Some aspects of Rocky Mountain spotted fever as shown by recent investigations. {Carpenter lecture.) Med. Rec, N. Y., 1909, LXXVI, 843-855. See also Contrib. to Med. Science, Ricketts, Univ. of Chicago Press, 1911, 373-408. See also Med. Sentinel, Portland, Oreg., 1909, XVII, 674-700. 53. A micro-organism which apparently has a specific relationship to Rocky Mountain spotted fever. J. Am. Med. Ass., Chicago, 1909, LII, 379-384. See also Contrib. to Med. Science, Ricketts, Univ. Chicago Press, 191 1, 368-372. Ricketts, (H. T.) and Gomez, (L.) 54. Studies on immunity in Rocky Mountain spotted fever. J. Inf. Dis., Chicago, 1908, V, 221-244. See also Contrib. to Med. Science, Ricketts, Univ. Chicago Press, T911, 343-367. (Abstracted in Science, N. Y., and Lancaster, Pa., 1908, n. s., XXVII, 651.) Ricketts, (H. T.) and Wilder, (R. M.) 55. The relation of typhus fever (tabardillo) to Rocky Mountain spot- ted fever. Arch, of Int. Med., Chicago, 1910, V, 361-370. See also 28 P. A. SURGEON n\ C. KUCKUR. Contrib. to Med. Science, Ricketts, Univ. Chicago Press, 1911, 479- 490. Robinson, (A. A.) 56. Rocky Mountain spotted fever, with report of a case. Med. Rec, N. Y., 1908, LXXIV, 913-922. Ross, (P. H.) and Milne, (A. D.) 57. Tick fever. Br. M. J., Lond., 1904, II, 1453. S AMBON, (L. W.) 59. The spotted fever of the Rocky Mountains. Sys. of Med., Albutt and Rolleston, II, pt. 2, 307-313. Shipley, (A. E.) 60. The infinite torment of flies. Med. Rev., St. Louis, 1905, XXIII, 445. Smith, (R. J.) 61. A case of. spotted or tick fever. Alkaloid. Clinic, Chicago, 1904, XI, 1252-1254. Smith, (W. F.) See Stewart. Spencer, (W. O.) 62. Mountain or spotted fever, as seen in Idaho and eastern Oregon, Med. Sentinel, Portland, Oreg., 1907, XV, 532-537. Stewart, (J. L.) and Smith, (W. F.) 62,. Clinical phases of Rocky Mountain spotted fever. Med. Sentinel, Portland, Oreg., 1908, XVI, 704-711. Stiles, (C. W.) 64. Preliminary report upon a zoological investigation of the so-called spotted fever of the Rocky Mountains. Ann. Rep., Surg. Genl., U. S. Pub. Health and Mar.-Hosp. Serv., 1904, Wash., Govt. Print. Office, 1904, 362-363. 65. Preliminary report upon a zoological investigation itito the cause, transmission, and source of the so-called spotted fever of the Rocky Mountains. Pub. Health Rep., U. S. Pub. Health and Mar.- Hosp. Serv., Wash., 1904, XIX, 1649. 66. A zoological investigation into the cause, transmission, and source of Rocky Mountain "spotted fever." Bull. 20, U. S. Pub. Health and Mar.-Hosp. Serv., Hyg. Lab., Wash., Govt. Print. Office, 1905. 67. Zoological pitfalls for the pathalogist. Proc. N. Y. Path. Soc, 1905, 1-21. 68. The common tick (Dermacentor andersoni) of the Bitter Root Val- ley. Pub. Health Rep., U. S. Pub. Health and Mar.-Hosp. Serv., Wash., Govt. Print. Office, 1908, XXIII, 949. 69. The taxonomic value of the microscopic structure of the stigmal plates in the tick genus Dermacentor. Bull. 62, U. S. Pub. Health and Mar.-Hosp. Serv., Hyg. Lab., Wash., Govt. Print. Office, 1910. 70. The correct name of the Rocky Mountain spotted fever tick. J. Am. Med. Ass., Chicago, 1910, LV, 1909-1910. ROCKY MOUNTAIN SPOTTED FEVER. 29 TUTTLE, (T. D.) 71. Some indications for state control of Rocky Mountain tick fever. Med. Sentinel, Portland, Oreg., 1908, XVI, 697-711. Wilder, (R. M.) , See RiCKETTs. "Wilson, (L. B.) and Chowning, (W. M.) 72. The so-called "spotted fever" of the Rocky Mountains. A prelim- inary report to the Montana State Board of Health. J. Am. Med. Ass., Chicago, 1902, XXXIX, 131-136. y2,. Spotted fever of Montana. Med. Sentinel, Portland, Oreg., 1902, X, 238-239. 74. Report on the investigation of so-called spotted fever. First Bien. Rep. Montana St. Board of Health, Helena, 1903, 26-91. 75. Studies in pyroplasmosis hominis, "spotted fever," of the Rocky Mountains. J. Infect. Dis., Chicago, 1904, I, 31-57. Wood, (M. W.) 76. Spotted fever as reported from Idaho. Rep. Surg. Genl., U. S. Army, 1896, Wash., Govt. Print. Office, 1896, 60-65, THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DU^. THE PENALTY WILL INCREASE TO 50 CENTS ON THE FOURTH DAY AND TO $1.00 ON THE SEVENTH DAY OVERDUE. MAY 4 193f. tVlAR 221937 DEC 2 19^ JMN 2 <^ I9b4 \ -^ jAM 1-^ 1^^^ APR 26 1937 APR 1 1233 AP[? ^"^ i93j ^^'^' 12 1933 •^^^^^ 8 IMO FFP 14 1942 7 1943 '^mMh. LD 21-100m-7,'33 -■■' ^44-50/ RCI64. 97K8 BfOLGG/ LiBBARY THE UNIVERSITY OF CALIFORNIA UBRARY