ANNUAL REPORT, 1941 101 



Poultry Farm. There were 147 females and 61 males. A wide variet\' of diag- 

 noses was made on these birds, but no unusual outbreaks of disease were noted. 

 The mortality in this \ear's flock was widely distributed over the year, whereas 

 the mortality in flocks hatched in previous \ears had a tendency to be con- 

 centrated in the late spring or just after the birds were more than ane year of age. 

 Cannibalism was materially reduced in this group of birds, whereas fowl paralysis 

 and staph\lococcosis were markedh' increased. 



4. Salmonella Types Isolated. The identification of paratyphoid organisms 

 isolated from diseased specimens continued during the past year, and 21 were 

 added to those previously reported. Eighteen were S. typhi- murium, one was 

 5. anatum, and two (from different organs of the same specimen) appear to be a 

 new type. These 21 strains came from six flocks. One strain was isolated from 

 a pigeon and all others from turkeys (7 mature and 13 poults). 



During the past year, 4104 turkey blood samples were tested for paratyphoid 

 infection by the macroscopic tube agglutination test. An autogenous antigen of 

 S. typhi-murium was used as a test fluid. While infected birds can be detected 

 by such a procedure, the method can not be relied upon to eliminate the infec- 

 tion to the degree accomplished in pullorum-disease testing. Owners of flocks 

 that are apparently free of this infection should investigate thoroughly the 

 history of the source from which stock may be introduced. 



We are greath- indebted to Dr. Philip Edwards, Department of Animal Path- 

 ology, University' of Kentucky, Le.Kington, Kentucky, who identified these 

 strains as to type. 



5. Avian Encephalomyelitis . The infective agent was passed through chicks 

 (intracerebral inoculation) 21 times during the past year and is now in its 125th 

 passage since its first isolation. Its characteristics do not appear to have under- 

 gone any permanent change during the twelve months. An attempt was made to 

 determine the presence of avian encephalomyelitis virus in the brain of adult 

 birds which had e.xhibited topical s\mptoms of the infection as chicks. Six hens 

 of this type were destroyed and brain suspension prepared from each for inocula- 

 tion intracerebrally into bab}' chicks. In no instance did the brain suspension 

 produce symptoms of avian encephalomyelitis. A suspension prepared from the 

 ovary of one of the six birds also gave negative results when inoculated into baby 

 chicks. The virus appears to lose its potency very slowly if stored at 10° C. ±. 

 This conclusion is based on inoculation of three brain suspensions prepared 

 10/8/38, 4/12/39, and 8/24/39 and stored until 1 21 41. The oldest (stored 

 837 days) produced t\pical symptoms in 50 percent of the chicks inoculated; 

 the next oldest (stored 650 days), in 67 percent of the chicks; and the most recent 

 (stored 517 da\s), in 86 percent of the chicks. 



Additional data were obtained from inoculation of embryonated eggs and trans- 

 mission of infection to chicks hatched in the incubator at the same time with the 

 inoculated embryos. A total of 188 ten-day embryos was inoculated in six dif- 

 ferent settings of eggs. Of the 91 chicks hatched from these embryos, 23 showed 

 typical sAmptoms of avian encephalomyelitis. Seven of these chicks showed 

 symptoms before they were taken fromthe hatching tra>', and one chick showed 

 no symptoms until it was 29 da>s of age. All others showed symptoms at ages 

 between these extremes. None of the 107 chicks exposed in the incubator while 

 hatching developed s)'mptoms of avian encephalomyelitis infection. The elTect 

 of fumigation on brain suspensions of avian encephalomyelitis v^rus was in- 

 vestigated in three trials. Chicks inoculated with a virus suspension previously 

 fumigated by the standard formaldehyde gas method did not develop clinical 

 symptoms. 



Consignn^ents of chick brains were received from Georgia, New Mexico, 



