ERADICATION OF PULLORUM DISEASE 1931-32 



45 



whose serum completely agglutinated the antigen in a dilution of 1 :20 or higher 

 was considered to be a reactor. Immediately upon detection, reactors were iso- 

 lated in individual cages and the pens were cleaned thoroughly. After all of the 

 reactors were detected, the non-reactors were tested at biweekly intervals. 



Group A consisted of 50 chicks which were subjected to one exposure. At 

 the age of 23 days, 1 chick died and 5. pidloriim was isolated. All the reactors, 

 16 in number, were detected by the end of the ninth week. Observations con- 

 cerning 32 chicks made during the period between the fourth and eighteenth 

 weeks are shown in Table 16. 



S. ptillorum was isolated from 2 of the 5 non-reactors and from both of the 

 reactors which died. Of the 19 non-reactors which were killed, 5. pullorum was 

 isolated from 1 (No. 302). This chick had been considered a reactor in earlier 

 tests. 5. pullorum was isolated from 3 of the 6 reactors which were killed. 



At the end of the eighteenth week, 10 non-reacting and 7 reacting pullets 

 remained in Group A. The non-reacting pullets were placed in individual cages 

 at the age of 5 months and, with one exception, were retained until at least 1 

 month after having attained sexTial maturity. This 1 bird was killed because of 

 infectious laryngotracheitis at approximately 9 months of age. The agglutina- 

 tion reactions indicated these 10 birds to be non-reactors at aU tests, and 5. pul- 

 lorum was not isolated. 



Data concerning the 7 reacting pullets are shown in Table 17. 



Table 17 — Serological and Necropsy Data Concerning Seven Pullets 

 Exposed to Artificial Infection as Chicks (Part V) 



Sexual maturity was attained by 5 birds, which were killed 2 months later, 

 and 5. pullorum was isolated from 2. The agglutination titers of 2 of the other 

 3 birds gradually became lower. At the age of 41 weeks, the 2 pullets which had 

 not attained sexual maturity were killed, and S. pullorum was isolated from both. 



Group A-1 consisted of 24 chicks which were subjected to two exposures. 

 By the end of the ninth week, 11 reactors were detected. Observations con- 

 cerning 14 chicks, made during the period between the fourth and eighteenth 

 weeks, are shown in Table 18. 



5. pullorum was isolated from 1 (No. 253) of 7 non-reactors and from 2 of 7 

 reactors. The sera of 3 (Nos. 257, 270, and 273) of the 7 reactors did not produce 

 complete agglutination in some of the tests prior to necropsy. 



At the end of the eighteenth week, 6 non-reacting and 4 reacting pullets re- 

 mained in Group A-1. The non-reacting pullets were placed in individual cages 

 at the age of 5 months and, with two exceptions, were retained for at least 1 

 month after having attained sexual maturity. The first of these 2 was killed 

 because of "paralysis" at approximately 5 months, and 5. pullorum was not 



