UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA A SURVEY OF INFECTIOUS LARYNGOTRACHEITIS OF FOWLS W. R. HINSHAW BULLETIN 520 NOVEMBER, 1931 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1931 A SURVEY OF INFECTIOUS LARYNGOTRACHEITIS OF FOWLS 1 W. B. HINSHAW2 FOREWORD Infectious laryngotracheitis (infectious bronchitis, Canadian flu, infectious tracheitis) has been increasing in economic importance in California since the fall of 1924. During October, 1929, the disease became unusually serious in the Petaluma district and continued for two months, sweeping completely through the concentrated area. At the request of the poultry industry, Dr. H. W. Graybill of the State Department of Agriculture, and Dr. J. R. Beach of the University of California, and the writer were asked to make a disease survey of this district. Owing to the assignment of Dr. Beach to the Rockefeller Institute for research on this disease, the survey was made by the other members of the committee. After completion of the Petaluma survey in March, 1930, the studies were continued in other parts of the state by the writer, in cooperation with Dr. Graybill and Dr. E. E. Jones of the Los Angeles County Livestock Department. INTRODUCTION These studies have been an attempt to determine the relation to the disease of the various factors encountered in the field, to establish the status of the disease in this state as well as in the United States at the present time, and to obtain information which would aid in making recommendations for the control of the disease. Admittedly, data collected in such a survey are lacking in detail. Whenever possi- ble, records kept by poultrymen have been consulted, and the most intelligent and reliable men in each district have been sought in order to make the information more authentic. The survey is presented with the knowledge that it has limitations but with the belief that it is representative. i This disease has been described under the name ' infectious bronchitis ' in California Agr. Exp. Sta. Bui. 494. Since the publication of that bulletin it has been found that the name 'infectious laryngotracheitis ' is more descriptive of the disease, and most poultry-disease workers have accepted the latter name. This accounts for the change in the use of the name in this report. 2 Associate Veterinarian in the Experiment Station. 4 University of California — Experiment Station To collect the data, the investigators prepared and took into the field a comprehensive questionnaire and obtained the information by personal interviews with poultrymen, veterinarians, farm advisors and service men. In all, 219 ranches were visited during" the survey, and approximately 1,000 more persons (poultrymen, feed dealers, service men, etc.) were approached through seventeen poultry meetings. Various factors, such as methods used in cleaning and disinfecting poultry crates and second hand feed sacks, topography, type of soil, and weather conditions, were studied in each district to determine, if possible, their relation to the prevalence and spread of the disease. To procure data on the history of laryngotracheitis, the records of the University and State Department of Agriculture were studied, and veterinarians, county farm advisors, and others familiar with the disease in the various communities were consulted. Whenever possible, the ranches reported as having had losses in the fall of 1924 and in the winter of 1925 were visited to obtain information as to how the infection was introduced into the state. To secure information further than could be found in literature on the early appearance of the disease in the United States and Canada, correspondence was ex- changed with pathologists and poultry specialists of America, This was done in cooperation with the Poultry Disease Committee of the American Veterinary Medical Association (1930). 3 A fairly com- prehensive review of the literature on this subject was made in con- nection with the survey, and the bibliography obtained is herewith presented for the purpose of record. Many of the references are of greater historical than scientific value. HISTORY AND DISTRIBUTION OF THE DISEASE IN THE UNITED STATES AND CANADA Geographical Distribution. — The data included in table 1, which were obtained by personal communications and interviews, may fail to give the exact dates of the occurrence of the disease in the various states, but as far as can be ascertained, they are the first authentic records available in the respective states. Information received from Kentucky, Maryland, Virginia, and Wyoming, indicates that the disease exists in these states but that no official reports are available. The disease exists in Texas, Vermont, and Utah, but because those reporting were unable to give definite information as to the time of first outbreaks, these states are not included in table 1. To the best 3 See "Bibliography" at the end of the bulletin for complete data on citations, which are referred to in the text by author and date of publication. Bul. 520] Infectious Laryngotracheitis of Fowls 5 knowledge of those reporting the disease had not existed in Alabama, Arkansas, Idaho, Maine, Mississippi, Montana, New Mexico, South Carolina, West Virginia, and Hawaii, up to the time of making the report, during the spring and summer of 1930. According to Doyle 4 the disease has not been officially recorded in England. Van Heelsbergen (1929) has observed a disease in Holland in which "symptoms and anatomical changes are entirely like those described by the American authors." Judging from his description, however, the writer is inclined to believe that Van Heelsbergen is confusing a tracheitis caused by the fowl pox virus with laryngotra- cheitis. If this is not true, the cases he describes must have been associated with outbreaks of fowl pox, for he consistently refers to this virus as a probable cause of the disease, a supposition contrary to the latest reports on the disease in America by Beach (1930), Graham (1930a), and Kernohan (1930), and to observations made during the survey. Previous Existence. — Kernohan (1930) cites Salmon (1899), Rob- inson (1917), Kaupp (1917), Pearl, Surface, and Curtis (1920), and Ward and Gallagher (1920) as having described respiratory diseases resembling infectious laryngotracheitis previous to 1920. Table 1 shows that Orr believes it to have been present in Oklahoma as early as 1919 ; that Graham observed it in Illinois and Weaver in Canada in 1922 ; and that Beaudette in New Jersey, Brunett in New York, and May and Tittsler (1925) in Rhode Island diagnosed it in their respective states as early as 1923. Hallman (1923) reported a diagnosis of acute purulent tracheitis in Michigan during the year 1923. Gwatkin (1924) described outbreaks of a similar disease under the name of avian diphtheria following poultry shows in Canada during the fall and winter of 1923-24. From the historical information available, this disease appears to be one confined principally to the North American continent, and most investigators believe that it had existed for many years before being diagnosed. Not until the summer of 1924, however, did it become of economic importance in the United States. On October 7, 1924, H. F. Jones, executive secretary of the National Poultry, Butter, and Egg Association, in a circular letter to poultry buyers, county agents, and others, called attention to " ... a peculiar disease which is reaching various markets of the country." The disease referred to proved to be the one now known as infectious laryngotracheitis, although at that 4 T. M. Doyle, personal interview, 1930. University of California — Experiment Station ^ b 9 § EH o 00 03 O bO 03 bD O oo 03 >> s 03 a h O 73 03 oo 3 q o 4) 00 03 a o S3 73 03 U O ft oo 00 CO ec (4 11 la GO ■** I.s. 03 73 03 > 03 ~o3 3 a o "o3 00 .s 'S 05 03 a o X ■ M •a a «* .5 a .2 x* w -*^ 00 00 _s 03 00 «•, 3 52 _o "o! '% c3 £ CO ,£3 03 a oo 03 03 U 0) 00 03 ■*« 05 > 03 05 (^ X £§a >1l CD* ft ° o3 oo 3 73 03 03 3 ^ 03 00 3 O 05 3 03 -^ O 05 ^ 05 > 03 >> rt 0) U os « a 05 05 fi "3 a M 03 05 a 03 « 03 X! 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PC "S 3 3 pq 73 3 03 U Ji e -73 33 fl 3 -§o?s§ o3 fe 3 & 03r5 o S hj3 'o3 o >s 03 M 3 73 G^TX g a.s a a 73 3 03 3 a s> Pi £ 5 o PC hJ PMq " • . 03 < 03 X O PEs« -iO ^H W Otf pq w «^ p4 k4^e^* WW > o CO OS go Ol 00 05 03 > WO 00 73 00 ,9 GO 3 05 a £v CO i3 be 3 t- M h a Fh fl 03 o3 03 03 o3 o3 03 "o OS- 'oo o3 0) N 03 a MS a ■>*< o a a «5 go a go OJ 0) CM 03 CN CO 05 o OS 05 fc OS ^2 03 0Q CO a •> ' o 03 a 73 o 00 OQ I X 12 00 'o _3 o3 3 03 o .2 03 3 > OJ -s 05 u 03 73 3 ^03 03 73 O X - a u o "o3 03 3 .2 73 3 03 00 03 00 3 o3 3^ be 05 ^ a 3 O 00 O « O & fe PC? o O M ii § a o go 03 05 s a 3 03 0> 03 u h O s a a 03 05 x 03 X 3 XI s a a a a to o o o X 03 3 3 o e o H S3 S3 o > [S ft bfi SSj 3 ■S s o o o3 a O 43 o 03 3 03 3 03 fc fe h Uh fe O fe fe OQ -5 g '*3 3 B o a m m ha 3 o e O Occurred in epizootic form in 1929. First outbreak at Las Vegas. The only other record is that of a case near Reno in 1930. During 1929, 6 more outbreaks were reported. L. Van Es B. F. Kaupp A. F. Schalk R. 0. Biltz, E. L. Stubbs, and R. P. Tittsler B. A. Beach I. E. Newsom G. L. Dunlap and C. S. Gibbs L. W. Goss M. Jacobs W. R. Gunn D. E. Warner W. C. Burkhart C. W. Upp C. E. Sawyer 3g 2S 3 2 a H WW a a d d H. R. Baker K. W. Niemann C. A. Bottorff W. T. Johnson 1924-25 No comment See remarks 1924-25 See remarks 1925 No comment Occurs sporadically 1926 See remarks No comment 1926 1926 Increasing yearly u a a 03 03 V o <- ti o o C G 7 OS 1929 See remarks No comment Sporadic outbreaks Nebraska North Carolina North Dakota Pennsylvania Wisconsin Colorado Massachusetts Ohio Tennessee British Columbia, Canada Connecticut Georgia Louisiana Washington c3 6 aa c -3 3 o Delaware Nevada New Hampshire Oregon Fall Fall No comment Fall Fall January November No comment No comment No comment No comment Fall Fall June 4 u 0) a*? 3 a COCO No comment No comment January 15 March 15 CM 00 "■0 3 3 8 §5 8 University of California — Experiment Station time many confused it with fowl pest, which existed simultaneously in the eastern part of the United States. References to the epizootic of infectious laryngotracheitis of 1924 and 1925 have been made by Beach (1925, 1926), Beaudette (1925), Eriksen (1924, 1925), Gwatkin (1924, 1925), Gouge (1926), Hendrick- son (1926), Hinshaw (1924, 1925), Kaupp (1924), McCosh (1925), and Stafseth (1925). Present Status. — The present status of the disease in America is difficult to determine. The correspondence received from the various states shows, however, that laryngotracheitis is increasing in im- portance in most of the important poultry-producing states and provinces. It was the general opinion that poultry-fattening stations in the Middle West were either having less trouble with the disease or were in a better position to keep it under control, but that more farm flocks in that region were being affected annually. Poultry shows, egg-laying contests, and similar exhibitions were generally conceded to be important agencies of dissemination. A respiratory disease of chicks which resembles infectious laryngo- tracheitis has been increasing in importance in the middle western and eastern states, according to Beaudette and Hudson (1931), Bushnell, 5 Fitch (1931), Graham, Thorp, and James (1930a), Schalk and Hawn (1931), and Taggart. 6 Kernohan (1931a) and Sawyer (1929) have reported the disease in young chicks in California and Washington. Reference to the importance of the disease in chicks in California will be made later. HISTORY AND DISTRIBUTION IN CALIFORNIA Early History. — The first authentic record of the occurrence of laryngotracheitis in California is a report of a diagnosis made by Dr. J. R. Beach on November 20, 1924 on chickens sent to the Division of Veterinary Science from Hayward. A record obtained from Dr. J. P. Iverson, State Department of Agriculture, shows that a. diagnosis of the disease was made in poultry at Pasadena in November, 1924 (exact date not available). On December 17, 1924, Drs. J. R. Beach and D. E. Davis of the University, and Dr. F. D. Marquis of the State Department of Agriculture investigated an outbreak in a car- load of poultry consigned to Oakland from Nebraska. Another out- break of laryngotracheitis in a car of live poultry was investigated at Oakland by the State Department of Agriculture on January 30, 1925. 5 L. D. Bushnell, Manhattan, Kansas, personal communication. 6 J. I. Taggart, Cleveland, Ohio, personal interview. Bul. 520] Infectious Laryngotracheitis of Fowls 9 Since official inspection of cars of live poultry by the State Depart- ment of Agriculture was not begun until the early part of December, 1924, it was impossible to determine whether or not shipments of birds from the Middle West may have suffered similar losses before that time. A diagnosis of the disease was made January 15, 1925 by Dr. Beach in chickens shipped from Owensmouth, Los Angeles County. Further investigation of this case, made during the survey, showed that the specimens were shipped from a poultry colony near Owens- mouth and that the disease has existed there since November, 1924. Information from reliable sources in Pasadena and Arcadia shows that there was an epizootic of the disease in Arcadia in the fall and winter of 1924-25 and that it started in October or November, 1924. Evidence that the disease has existed in the Arcadia district since 1921 or 1922 was also secured though authentic case reports were not available. Records of diagnoses in Monterey and Palo Alto during January, 1925, and in Petaluma in February, 1925, are on file in the Division of Veterinary Science at Berkeley. The first Petaluma outbreak was reported on February 9, 1925, and was diagnosed by Dr. D. E. Davis, then in charge of the University Poultry Disease Laboratory at Peta- luma. Reports of earlier outbreaks in Petaluma were investigated but no data were obtained to substantiate their authenticity. Diagnoses were also made in 1925 in birds from Hopland, Rio Linda, Hollister, Norco, and Santa Cruz. Thus, by the end of 1925, the disease had gained a foothold in many poultry sections of the state. Method of Introduction. — All attempts to determine how infectious laryngotracheitis was introduced into California were futile. As the disease is known to have existed in the Middle West as early as August, 1924, it is probable that sick birds arrived at the numerous terminals within the state, but there are no authentic records of the disease being transmitted to farm flocks from these sources. The possibility that poultry within the state suffered losses from a respira- tory disease resembling laryngotracheitis as early as 1921 or 1922 makes it just as likely that the 1924 outbreaks originated from within the state as from diseased poultry shipped into the state from the Middle West. No information to substantiate either theory was ob- tained during the survey. Present Distribution. — Table 2 summarizes the authentic reports of initial outbreaks by years, and the distribution of these is given graphically in figure 1. These records were secured from the files of 10 University of California — Experiment Station the Division of Veterinary Science, from the Los Angeles Poultry Pathological Laboratory, and from poultrymen visited in the 1930 survey, and are complete to August 15, 1930. The numbers within the circles in figure 1 indicate the year of the first diagnosis of the disease Fig. 1. — Location of initial outbreaks and year of occurrence of infectious laryngotracheitis in California. in that area. A glance at the figure will give an idea as to how this disease is spreading to the more or less isolated poultry districts of the state. It may exist in sections other than those recorded, but accurate information is lacking. Bul. 520] Infectious Laryngotracheitis of Fowls 11 a b* d re o re 3 2 o a 3 o a o- re co re re 3 o* re 3 3 3 re 2 ■ << > p re 3* re a- 3 P «-. P 3 C P o 3 b o (V a- f? •< •< B* ?r B O 3 £3 O 3^9w P *j> ^ 3S P (?* P P 2^ P - aag * EL gs-§s P S o- 3 to to WMO CO O O £&& S P 3 S.B P 3 p P GO P 3 P O 3 M s E O co 15 3 P w o « p" 3 0- re E 3 p Mg O 3 >re r* re 0<< to ?r Downey Bellflowe Inglewoo Van Nuy San Fern (3 1?? £ W re o CD •a p re O p 2- Br «o B o^ to Pu towh >• or >go o ^g 2 W hj GO jjft) p p a 3 p p 3-o p o o S 3 c P ° ^ - a WB* P 5 3 re 3 2 5'g.g CO 5?B re 3 <* < pSS P3 33P P c^o 3* S 3 re P J3 CO » re P re P 3 P o- P 3 K 3 re f s B re "* r«al< Z5 I I I I I I I I I CUUoU Z4 Fig. 6. — Mortality and egg production during outbreaks; representative outbreaks from table 7. 24 University of California — Experiment Station tendency. It will be noted that the production was not markedly affected until 5 days after the onset of the disease. The minimum pro- duction occurred 18 days after the onset of the disease, or 7 days after the maximum mortality. Production did not equal that previous to the outbreak until 34 days after the inception of the disease, or 29 days after production began to decrease. There was a maximum drop of approximately 12 per cent during the period. Figures 5 and 6 show representative outbreaks from table 7. Out- breaks 2 and 23 were in young birds which had been laying for a few weeks previous to the onset of the disease. Outbreak 24 is an example of young birds in which the laying period was some- what retarded and in which the disease with a slightly above-normal mortality had little effect on the ultimate percentage produc- tion. Outbreak 11 was in a flock which on November 1 was in 15 per cent production and which by November 20, the first day of the disease, had increased to 40 per cent production. As in outbreak 24, the disease slightly retarded production but did not seriously affect it. Outbreak 21 was in two-year-old hens, and outbreak 25 was in a house consisting of 77 per cent old hens and the remainder pullets. In the latter, the disease started in the pens of old hens on October 20. and in the one pen of young pullets on October 27. Separate records for the two groups could not be obtained and therefore both the mortality and the egg-production curves are somewhat affected by this factor. Most poultrymen believe that this disease has little if any effect on the recovered bird, provided no complications accompany or follow the outbreak. The only information obtained on this subject is sum- marized in table 8. These birds were in the Southern California Egg Laying Contest, and all were removed from the original pens to the hospital where they recovered before being returned. The information was furnished through the courtesy of Mr. Irving Denny. The birds suffered from the disease during November and December. The data, though limited, are considered accurate because they were taken from trapnest records at an official institution cooperating with the Los Angeles Poultry Pathological Laboratory. In the group of 23 birds reported in table 8 it will be noted that only 3 birds laid eggs in December, 14 laid in January, and all but 4 in February. According to Mr. Denny 11 of those laying in Feb- ruary failed to pay their feed bill ; only 6 of the 23 birds reached the flock average for the year ; and 8 of them could not be considered profitable producers. Bul. 520] Infectious Laryngotracheitis of Fowls 25 TABLE 8 Production After Kecovery from Infectious Laryngotracheitis in One Flock During 1926-27 Hen To hospital Number of days in hospital Days to first egg after recovery Number of eggs laid No. Nov. Dec. Jan. Feb. Year 141 142 149 156 159* November 17 November 23 November 24 November 23 * 11 7 7 7 4 7 5 8 7 8 17 4 4 8 6 5 9 11 4 19 17 14 53 51 70 93 24 49 35 94 54 77 70 53 53 89 80 60 8 31 59 52 1 15 9 14 11 13 5 17 16 1 12 3 11 3 16 9 17 5 16 2 8 9 3 18 3 17 7 9 11 5 16 14 3 2 7 7 16 18 18 12 20 18 9 14 17 19 1 9 22 8 21 18 25 173 165 190 37 202 166 170 172 November 27 November 22 198 124 147 175 178 188 207 220 229 232 249 254 460 461 465 848J November 22 November 23 November 20 November 15 November 25 November 24 November 23 November 25 November 23 November 28 November 28 November 27 December 26 156 178 150 209 181 212 t 156 218 162 147 205 135 868J 869$ December 27 December 31 1 125 * Record not complete. t Number 232 was returned to the hospital December 28 to February 19 with a cold. In March it was again taken to the hospital and died April 12. t Nos. 848, 868, and 869 were of heavy breeds. 1 Number 868 did not lay an egg before its death on June 24, when it was found to be suffering from a diseased ovary. According' to the data, collected during the survey, approximately 90 per cent of the flocks in the congested poultry districts get this disease before they are twelve months old and 30 per cent develop it before they are five months old. At least 50 per cent suffer from the disease during the early laying period of their lives, or just as they are starting to lay. The loss in egg" production as well as the mortality loss in the diseased flock must therefore be considered. The loss in egg production has already been discussed and is treated graphically in figure 4. From the data used to produce figure 4, the loss in this group of 25 flocks has been estimated to be at least 22,604 eggs, which at 36 cents a dozen equals a monetary loss of $678.12. In order to make these calculations, it was assumed that the egg production for the 10 days previous to the drop caused by the disease was the normal production for the period. The total actual production subtracted from the estimated normal production gave 26 University of California — Experiment Station the estimated loss. As the majority of the outbreaks occurred in the late fall,. the price was considered slightly above the average price for the year. The mortality in this group was 1,916 birds, which were valued at $2,500.00. Thus the total loss was about $3,200.00 From these and other data obtained during the survey the usual monetary loss resulting from a drop in egg production is estimated to be at least one-fourth that resulting from mortality. These figures necessarily vary in individual outbreaks and are dependent on the breed of birds, the season of the year, the price of eggs, the percentage production, etc. SUSCEPTIBILITY OF FOWLS OTHER THAN CHICKENS Kernohan (1930, 1931a., 1931&) reported natural cases of diseases showing symptoms similar to those of infectious laryngotracheitis in turkeys, ducks, sparrows, blackbirds, quail, pheasants, and pigeons. Beach, 10 however, was unable to reproduce the disease by inocculation in sparrows, wild doves, crows, starlings, pigeons, ducks, rabbits, guinea pigs, rats, and swine. During the survey only two instances were found where fowls other than chickens had apparently suffered from this disease. One of these outbreaks occurred in pheasants at the same time that the disease was present among chickens in adjoin- ing pens. During this time there were six varieties of pheasants, several varieties of ducks, geese, pigeons, and canaries, as well as several peafowls, Indian green wing doves, a parrot, and other small house birds on the ranch. Only two varieties of pheasants (Golden and Amherst) developed symptoms, and according to the owner none of the other birds showed any indications of the disease at any time. Several bantam chickens suffered from the disease at the same time as the flock of White Leghorns. The second possible outbreak was in a pen of five or six-month-old turkeys located between two pens of chickens that suffered from an outbreak of the disease diagnosed in a poultry laboratory. None of the turkeys were taken to the laboratory but when the farm was visited several months later the owner described typical symptoms in the turkeys, which suffered immediately after the outbreak among the chickens. Information was secured from at least 20 other ranches where both turkeys and chickens were kept and where the disease caused losses in chickens with no symptoms among the turkeys. In many of these instances, the turkeys were penned in yards adjoining those of chickens. io J. R. Beach, personal communication, March 24, 1931. Bul. 520] Infectious Laryngotracheitis of Fowls 27 A limited amount of information from pigeon growers indicated that this disease is not a problem in that industry. No reports of outbreaks of a similar disease among pigeons were obtained. One ranch where several thousand pigeons are raised annually and cared for by the same attendants who handle the 3,200 chickens has experi- enced at least three severe outbreaks among the chickens with no losses or similar symptoms among the pigeons. The disease, in its usual form at least, is not common among wild birds and appears to be one primarily affecting chickens. TREATMENT AND CONTROL The observations made show that no satisfactory medicinal treat- ment for infectious laryngotracheitis has been found. Most poultrymen who have had several years of experience with the disease have con- cluded that good management, careful nursing, and attention paid to diet and comfort of the birds during an outbreak will do more to prevent excessive losses than sprays, bronchitis pills or capsules, or other forms of medicinal treatment, • However, in spite of what Beaudette and Hudson (1930), Kernohan (1930), and other experi- ment station workers have found to the contrary, a surprisingly large number of poultrymen have concocted a so-called remedy, which, according to their claims, will cure the disease. The number of proprietary remedies for this disease that are being sold in California cannot be accurately estimated. Practically every poultry community in the state has one or more drug peddlers who have a 'sure-cure' for this disease. In addition to the locally-manu- factured products, numerous advertised nostrums have been sold to poultrymen. The nostrum salesmen nearly always demonstrate their products on birds that have passed through the first week of the disease and without leaving any untreated birds to act as checks or controls. A glance at figure 4 will show that the natural course of the disease is such that a remedy given at the end of the first week might easily be supposed to produce good results when, as a matter of fact, the disease was passing through a normal course. Many of the nostrums used, some of which are sprays, have unquestionably done more harm than good, and have apparently been mixed together with little thought of chemical reactions or incompatibilities. Thousands of dollars are annually wasted by poultrymen for these drugs, the benefits of which are principally to the manufacturer and salesman who profit by the sales. If poultrymen would insist on leaving pens of untreated birds for checking the natural outcome against the out- 28 University of California — Experiment Station come of treated pens in all cases where salesmen desire to demonstrate a new untried product, fewer sales would be made and less money would be wasted on worthless remedies for this as well as other poultry diseases. One practice which apparently has aided in preventing heavy losses in laying flocks is to stop egg production by having the protein content reduced in all pens that have not previously suffered attacks of the disease ; this should be done at the first indications of the disease in a flock. In these cases the birds are encouraged to eat as much grain as possible in order to prevent lowered resistance. Crushed or rolled oats or barley soaked in milk is in common use for this purpose in some poultry sections. So far as the writer knows, this method of preventing losses has not been tried under experimental condi- tions, and can be considered only an observation. Another observed procedure that appeared to have merits was a practice of keeping sick birds in small units in an artificially-heated and well-ventilated room. Excessive handling of infected birds and unnecessary excitement appear to increase losses. This fact would suggest that wholesale spraying of birds is contra-indicated even though the spray itself might be of some value. Relieving suffocating birds by removal of the exudate which often collects in the superior larynx and separation of sick birds into small units in warm, well-ventilated rooms have appar- ently saved many birds. PREVENTION Infected Areas. — The subject of prevention can be conveniently discussed from two viewpoints, i.e., infected areas and noninfected areas. Little information of an encouraging nature regarding pre- vention in infected areas where the poultry population is congested was obtained during the survey. Keeping flocks healthy and free of parasites, avoiding overcrowding, and practicing the best possible feeding and housing procedures along with a strict observation of sanitary measures are all points well worth considering. In congested poultry sections, community problems arise which make it difficult for the individual to cope with the situation. The constant brooding of chicks in the community furnishes a medium for the continual propagation of the virus in susceptible birds. The carrier must be considered as a possible means of dis- semination, and care should be taken to avoid unnecessarily intro- ducing the disease by mixing susceptible stock with birds that have once been affected. The practice of purposely introducing infected Bul. 520] Infectious Laryngotracheitis of Fowls 29 birds in pens of young stock to allow the disease to take its toll before the laying season starts cannot be recommended until proved an efficient method under experimental conditions. The mechanical carrier problem is one yet to be solved, but never- theless one which cannot be ignored in communities where poultry ranches are in such close proximity to each other as in localities such as Petaluma and the San Fernando Valley. Methods of disposal of dead birds, manure, and litter; cleaning and dissinfection of second- hand feed sacks and poultry crates ; and the control of sparrows, rats, dogs, etc. are problems that can be best handled by an official sanitary supervision of the individual district. The supervision of the Peta- luma district under the direction of the State Department of Agri- culture with funds appropriated by the district is an example of an attempt to solve health problems in a concentrated poultry community. The method of disposal of dead birds used, under proper sanitary supervision, in the Petaluma district appears to be one that might be applicable to other districts. A commercial scavenger concern in Peta- luma has specially constructed leak-proof trucks, which are used to pick up the dead birds at the ranch under private contract with ranch owners. The ranch owner places all dead birds in a closed garbage can at the entrance of the ranch on the day of collection, and these dead birds are placed in the trucks and hauled to a fertilizer factory where they are sterilized and made into fertilizer. The truck is steam cleaned each night. This method appears to be reasonable in cost to the rancher and when properly handled under official supervision, to be superior to burial or incineration on the ranch. Some of the disadvantages and dangers of such a system are: carelessness in placing dead birds in the truck, improper cleaning and disinfection of the truck, carelessness on the part of the poultrymen in keeping all dead birds in the closed garbage can, failure to provide sufficient receptacles so that the cover may always be tightly clamped on the can, and improper daily cleaning and disinfection of the garbage can itself. Next in importance to the method of disposal of dead birds is perhaps the handling of manure and litter in congested areas. In southern California this problem is not so vital as in northern Cali- fornia because there is a ready sale in that section of the state for poultry manure and litter as fertilizer for citrus orchards. In the northern part of the state it is often impossible to find a buyer for this by-product, and it was not uncommon during the survey to see several months' collection stored in yards, with the drainage from these storage places towards the adjoining poultry ranch yards. Poultry- 30 University of California — Experiment Station men in such communities will do well to attempt organized efforts to eliminate, by suitable means, this source of contagion. The possibility of spread of disease during transportation should of course be guarded against by use of properly constructed vehicles that will prevent loss of the manure en route. Noninfected Areas. — In localities where the disease has not yet been introduced, the same community precautions as are applicable to infected areas should be observed. A single brooding season, care in introduction of new stock, thorough cleaning and disinfection of poultry crates and used feed sacks before allowing them to be brought from infected into disease-free areas, are other examples of methods of prevention. The purchase of adult stock should always be dis- couraged from the standpoint of prevention of all poultry diseases. The buying of day-old-chicks from healthy flocks is much the safer way to add replacements. Hatcherymen in infected areas should cooperate in preventing this disease by taking every precaution to avoid keeping chicks in battery brooders that are very near the incu- bation rooms, for there is danger of infecting chicks that are being packed for shipment if the disease is present in chicks being brooded by the hatchery. Beaudette and Hudson (1930) go so far as to dis- courage buying of chicks from premises known to be infected. Poultry shows, fairs, egg-laying contests, and all public exhibitions of poultry are likewise sources of disease dissemination, and if birds must be taken to such places they had better not be returned to the ranch after the exhibition is over. If they are returned, they should be placed in absolute quarantine for two weeks. If the disease is introduced into a previously free area, absolute quarantine measures and even destruction of the flock, followed by thorough cleaning and disinfection of the premises, appears to be a safe recommendation from the standpoint of the future health of the poultry in that community, as well as on the individual ranch. That such a procedure is workable was proved in one poultry subdivision in southern California. Infectious laryngotracheitis was introduced into two flocks by the addition of breeding cockerels; quarantine of the flocks prevented the disease from spreading to other flocks. Extreme care was used further to prevent spread, by cleaning and disinfection, and by burning of dead birds. As soon as the birds had recovered and were fit for market, they were sold for meat purposes. The premises were cleaned and disinfected and left vacant for about two months. Eigtheen months later, when the community was visited by the writer, no new outbreaks had occurred either on the formerly infected prem- ises or in other flocks. Bul. 520] Infectious Laryngotracheitis of Fowls 31 SUMMARY The information reported in this bulletin was collected during 1930 in a field survey covering the most important poultry sections of California, and by correspondence with poultry specialists and vet- erinarians in United States and Canada. Infectious laryngotracheitis (infectious bronchitis) has been rec- ognized in North America since 1922 and has been increasing in economic importance annually. It has been reported in at least 39 of the states and two of the provinces. In California, it was first diagnosed in November, 1924, and is now prevalent in most of the poultry sections of the state. The method of introduction into the state was not determined, though the disease was diagnosed in live poultry shipments from the Middle West at about the time of the initial outbreaks on poultry ranches in 1924. In the majority of the instances reported, the disease has been introduced into new localities within the state by the purchase of mature or partly grown stock from infected areas. Concentration of poultry ranches and continuous brooding of chicks in a community were found to be important factors influencing the yearly recurrence and spread of laryngotracheitis. Evidence to support the carrier theory was obtained, but controlled experimental data were lacking. Weather, topography, and housing were found to have little pre- disposing influence on the susceptibility of birds to the disease. There has been a seasonal trend of outbreaks in the state with the greatest number in the late fall and early winter but it has been impossible to determine whether or not this has been due to an age susceptibility or to a seasonal influence. The average mortality based on filed records on 75 flocks was 11.15 per cent with extremes of 0.00 to 48.66 per cent. There was no signfi- cant difference in the mortality in flocks of southern and northern California, The average course of the disease in the investigated cases was 15 days with extremes of 4 to 39 days. In a group of 25 producing flocks, 85 per cent of all deaths occurred within 15 days, and 98 per cent within 21 days. The greatest mortality occurred on the eleventh clay and 70 per cent of all losses were from the fifth to the fif- teenth day. Immunity is conferred by one attack of the disease. 32 University of California — Experiment Station In a composite group of 25 producing flocks the minimum produc- tion was on the eighteenth day after the onset of the disease, or 7 days after the maximum mortality. The production started to drop on the fifth day of the disease and reached the predisease percentage pro- duction on the thirty-fourth day after the onset, with a maximum drop during the period of 12 per cent. The monetary loss from drop in egg production was approximately one-fourth the monetary loss from mortality. Fowls and wild birds other than chickens are not as a rule suscep- tible to natural outbreaks of infectious laryngotracheitis. No satisfactory treatment for the disease was found. Careful nursing, attention to the comfort of the birds, avoidance of excessive excitement, and proper feeding were observed to be the best control measures. Prevention in an infected area is a community problem and con- sists of proper attention to disposal of dead birds, manure, and litter ; the control of mechanical carriers; attention to the cleaning and disinfection of secondhand feed sacks and poultry crates; and the control of community and plant sanitation, as well as individual atten- tion to the health of birds. Prevention in a disease-free area involves precaution in the introduction of stock, in addition to the above recommendations. ACKNOWLEDGMENTS The writer wishes to express his thanks and indebtedness to the staff of the Los Angeles Poultry Pathological Laboratory and to Doctors H. W. Graybill and E. E. Jones in particular, for their cooperation and aid in collecting the data for the bulletin. Apprecia- tion and acknowledgment are also given for the cooperation received from the various county extension services, veterinarians, and poultry- service men, who have aided in making these observations possible. Bul. 520] Infectious Laryngotracheitis of Fowls 33 BIBLIOGRAPHYn American Veterinary Medical Association. 1930. Report of Special Committee on Poultry Diseases. Jour. Amer. Vet. Med. Assoc. 77 (n.s. 30):503-506. Anonymous. 1925. The epizootic of bronchitis among chickens. Vet. Med. 20:106-107. 1929. Infectious bronchitis in fowls. North Amer. Vet. 10(9) :44-46. 1930. Respiratory disease in baby chicks takes big toll. U. S. Egg and Poultry Mag. 36:44-5. Beach, J. R. 1926. Infectious bronchitis of fowls. Jour. Amer. Vet. Med. Assoc. 68 (n.s. 21): 570-579. 1930. The virus of laryngotracheitis of fowls. Science 72(1887) : 633-634. Beaudette, F. R. 1930. Bronchitis in poultry. New Jersey Agriculture 12(5) :3-4. Beaudette, F. R., and J. J. Black. 1926. Poultry pathology section, frew Jersey Agr. Exp. Sta. 39th Ann. Rpt. 1925-26:389-390. Beaudette, F. R. and C. B. Hudson. 1930. Infectious bronchitis. New Jersey Hints to Poultrymen 18(12) :l-4. 1930. Some observations on an outbreak of infectious bronchitis in bat- tery brooded chicks. Proceedings of the 22nd Annual Meeting Poultry Sci. Assoc. July 9-11, 1930:74-77. MacDonald Col- lege, Quebec, Canada. Bunyea, Hubert. 1929. A survey of poultry pathology, past, present, and future; infec- tious bronchitis. Jour. Amer. Vet. Med. Assoc. 74 (n.s. 27): 468-^69. Bushnell, L. D., and C. A. Brandly. 1929. Poultry diseases and their prevention and control. Kansas Agr. Exp. Sta. Bui. 247:42-43. California Agricultural Experiment Station. 1925. California Agr. Exp. Sta. Rpt. 1924-25:72. 1929. California Agr. Exp. Sta. Rpt, 1928-29:108. Emmel, M. W. 1931. Spirochetosis associated with infectious bronchitis. Jour. Amer. Vet. Med. Assoc. 78(n.s. 31) :710-711. Eriksen, Sivert. 1924. The epizootic of bronchitis among chickens. Missouri State Poultry Board Year Book and Bien. Rpt. 1923-24:48-52; published by Mo. State Poultry Exp. Sta., Mountain Grove, Mo. 1925. The epizootic of bronchitis among chickens. Missouri State Poultry Exp. Sta. Avian Pathology 2(3) :6-8. 11 This bibliography contains references not discussed in the text. An attempt has been made to list all papers that relate to the subject of infectious laryngo- tracheitis. 34 University of California — Experiment Station Fitch, C. P. 1931. Infectious bronchitis of baby chicks. Vet. Med. 26:36. Gibbs, C. S. 1930. Infectious tracheitis. New England Poultryman ll(Dec.):71. 1931a. Saprophytic and secondary microorganisms occurring in the respiratory tracts of domestic fowls and chickens in health and disease. Jour. Bact. 21:97-109. 1931&. Infectious tracheitis. Massachusetts Agr. Exp. Sta. Bui. 273:1-55. Gouge, M. E. 1926. Infectious diseases of poultry of new importance. Vet. Med. 21: 333-334. Graham, B., and F. Thorp, Jr. 1929. Infectious bronchitis in poultry. U. S. Egg and Poultry Mag. 35:32-4. 1930. Pleomorphic micro-organism associated with acute avian laryngo- tracheitis. Jour. Inf. Dis. 47:83-86. Graham, Bobert, Frank Thorp, Jr., and W. A. James. 1930a. A note on avian laryngotracheitis. Jour. Amer. Vet. Med. Assoc. 77(n.s.30):587-594. - 1930b. Subacute or chronic infectious avian laryngotracheitis. Jour. Inf. Dis. 47:87-94. 1930c. The pathogenicity of a pleomorphic micro-organism isolated from avian laryngotracheitis. Jour. Inf. Dis. 47:340-344. 1931a. A filtrable virus-like agent in avian laryngotracheitis. Jour. Amer. Vet. Med. Assoc. 78(n.s. 31) :506-517. 1931&. A summary of laryngotracheitis investigation at the Illinois Experiment Station. U.S. Egg and Poultry Magazine 37:34- 41, 62. Gwatkin, Boland. 1925. Some notes on avian diphtheria. Ontario Vet. Col. Bpt. [Guelph, Ont., Canada] 1924:54-61. 1926. Further notes on avian diphtheria (chicken pox) tracheitis. On- tario Vet. Col. Bpt. [Guelph, Ont., Canada] 1925:64-68. 1929. Infectious tracheitis. Ontario Vet. Col. Bpt. [Guelph, Ont., Canada] 1928:61-63. Hallman, E. T. 1923. Michigan Agr. Exp. Sta.. Bpt., Dept. Anim. Path. Section 1922^23: 89. [Beport of diagnosis of acute purulent tracheitis.] Hendrickson, J. M. 1926. Beport of the Poultry Disease Diagnostic Laboratory at Farming- dale, Long Island. New York State Vet. Col. Ann. Bpt. 1925-26:57. Hinshaw, W. B. 1924. Studies in poultry diseases found in poultry feeding station. Natl. Poultry, Butter, and Egg Bui. 9(la):3-6. 1925. Infectious or epizootic bronchitis of chickens. North Amer. Vet. 6(5):17-19. 1931. Infectious laryngotracheitis of fowls. Vet. Med. 26(8) :324-327. Bul. 520] Infectious Laryngotracheitis of Fowls 35 Hudson, C. B. 1931. Neither a buyer nor a seller be. Proceedings of 22nd annual meet- ing Poultry Science Assoc. July 9-11, 1930. p. 78-81. [Mac- Donald College, Quebec, Canada.] 1931a. The influence and environmental temperature on the mortality in chicks inoculated with the virus of infectious bronchitis. [Ab- tract.] Abstract and notes on 23rd annual meeting Poultry Science Assoc, Lexington, Kentucky, Aug. 10-12, 1931. Illinois Agricultural Experiment Station. 1928. Measures sought for checking fowl bronchitis. Illinois Agr. Exp. Sta. 41st Ann. Ept. 1927-28:174-175. 1929. Establish many characteristics of fowl bronchitis. Illinois Agr. Exp. Sta. 42nd Ann. Ept. 1928-29:116-117. 1930. Pathogenic organism involved in bronchitis of fowls. Illinois Agr. Exp. Sta. 43rd Ann. Ept, 1929-30:104-107. Indiana Agricultural Experiment Station. 1928. Chicken pox and roup. Indiana Agr. Exp. Sta. Dept. of Vet. Sci. 41st Ann. Ept. 1927-28:62. 1929. Investigation of disease outbreaks. Indiana Agr. Exp. Sta. 42nd Ann. Ept. Dept. of Vet. Sci. 1928-29:70. Kaupp, B. F. 1917. Poultry diseases. 169 p. American Veterinary Publishing Co., Chi- cago, 111. 1924. Bronchitis a common ailment. Vet. Med. 19:651-652. 1929. Poultry diseases. 5th ed. 436 p. Alexander Eger, Chicago, 111. Kernohan, George. 1930. 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