ERADICATION OF PULLORUM DISEASE 1931-32 41 



Among 15 chicks 5 to 19 days of age, from 6 flocks, the sera of 14 chicks 

 were negative to the tube agglutination test and 5. pullorum was isolated from 

 10 chicks. The serum of 1 chick contained agglutinins, but not in sufficient 

 quantity to produce complete agglutination, and 5. pullorum was not isolated. 



PART II 



In three groups, at different times, 119 day-old chicks were exposed to arti- 

 ficial infection and 22 day-old chicks were used for control purposes. Among 

 the exposed chicks, 26 died and S. pullorum was isolated from each of these 

 chicks. The remainder, with the exception of 4 controls, were killed at various 

 ages. Blood samples were obtained immediately prior to necropsy. The results 

 of tube agglutination tests in dilutions of 1:25, 1:50, and 1:100 and bacteriological 

 examinations of 111 chicks are shown in the following table. 



♦Incomplete agglutination in one chick. 



Among 93 artificially exposed chicks, varying in age from 5 to 19 days, no 

 sera showed complete agglutination, and S. pullorum was isolated from 60. 

 The serum of 1 chick showed an incomplete agglutination in all dilutions, and 

 5. pullorum was not isolated. The 18 control chicks were negative to the tube 

 agglutination test and to bacteriological examination. 



Whole blood agglutination tests were made on 43 exposed and 4 control 

 chicks, and all reactions were negative.' 



Chicks were hatched, in two groups, from a flock of 19 reacting hens and 1 

 reacting male. A few eggs for the second hatch were obtained after a non- 

 reacting male had been added to the flock. 



For the first hatch, 123 eggs were placed in a Prairie State incubator (144 

 egg capacity). Three eggs were broken during the incubation period. Of the 

 remaining 120 eggs, 73 (60.83 per cent) were fertile, which yielded 22 (18.33 per 

 cent) chicks. However, only 19 chicks were suitable to be placed under the 

 brooder. In the second hatch, 135 eggs were placed in the incubator with the 

 following results: three eggs were broken during incubation; 98 (74.24 per cent) 

 were fertile and 21 (15.91 per cent) chicks were hatched. The chicks in both 

 groups were tested with the tube agglutination test in dilutions of 1 :25, 1 :50, and 

 1:100, and higher if the titer exceeded these dilutions. Both groups were also 

 tested with the whole blood agglutination test.' 



Group I consisted of 19 chicks. At respective ages of 3, 5, and 7 days, 3 chicks 

 died and 5. pullorum was isolated from 2; the remaining 16 and 2 controls of the 

 same age were killed on the seventh day. 



The antigen for the whole blood agglutination test was furnished by Dr. M. Dorset, Bureau 

 of Animal Indiistry, United States Department of Agriculture. 



