22 CONTROL SERIES No. 63 



Results 



All birds in both experiments remained negative to the tube agglutination 

 test. 



The 62 birds (16 died during the course of the two experiments) were necrop- 

 sied and S. pullorum was not isolated on necropsy. 



Conclusion 



While the number of birds was small and the duration of the experiment was 

 not sufficient to show definitely that pullorum disease is not spread through the 

 feces from infected hens, the results obtained would suggest that feces from 

 infected hens are not an important vehicle of transmission to older birds. 



DISSEMINATION OF S. pullorum INFECTION AMONG SEXUALLY 

 IMMATURE FEMALES 



Pullorum disease dissemination is a problem of great import in establishing 

 and maintaining pullorum disease-free flocks. Investigations have shown that 

 there are various modes of dissemination of the disease during the different ages 

 of a bird's hfe. The disease may spread readily among young chicks while af- 

 fected with an acute form of the disease. The causative agent has been recov- 

 ered from the feces of infected chicks. Rettger (70) isolated S. pullorum from the 

 feces of 2- to 3-weeks-old chicks which were artificially infected. Jones (51) 

 observed that non-infected chicks, (24 to 48 hours old), placed in a brooder pre- 

 viously occupied by infected chicks would contract the disease. Chicks revealed 

 the greatest susceptibility to infection during the first 24 hours of hfe. The pos- 

 sibilities of infection seemed to decrease as the chicks became older. Rettger and 

 Stoneburn (73) stated that the disease may be spread by infected feed and water, 

 hence normal chicks may acquire it by picking up contaminated feed and drop- 

 pings. Doyle (27) found that day-old chicks housed with infected hens contracted 

 the disease. Control chicks from the same hatch remained healthy for 1 month 

 when the experiment was discontinued. Mathews (63) found that chicks (24 

 hours old) fed feces from infected hens, as well as chicks placed in contact with 

 infected hens had not contracted the disease at 2 to 3 weeks of age. Mailman 

 (61) reported that the examination of intestinal contents of chicks as a supple- 

 mentary procedure to the culture of other organs increased the number of posi- 

 tive cases of S. pullorum 10 per cent. Emmel (34, 35) was able to isolate S. 

 pullorum from the intestinal contents of naturally infected chicks. He found in 

 15 chicks which survived an attack of pullorum disease that 5. pullorum persisted 

 in the feces of 13 chicks for 1 week, 8 chicks for 2 weeks, 3 chicks for 3 weeks, 

 and 1 chick for 5 weeks after the chmax of the outbreak. Kerr (56) made emul- 

 sions from fecal specimens collected from natural outbreaks of disease and re- 

 covered 5. pullorum. The organism was found to remain viable in the specimens 

 for a period of 101 days. Weldin and Weaver (97) were able to transmit the dis- 

 ease to healthy chicks by placing them in contact with feces from infected chicks. 

 Healthy chicks also contracted the disease when placed in contaminated pens, 

 when placed with diseased chicks, and when placed in pens adjoining those con- 

 taining infected chicks. 



It is also known that the disease may spread among infected and non-infected 

 adults through indirect or direct contact. Rettger, Kirkpatrick, and Stoneburn 

 (74) observed transmission of the disease when hens that had laid infective eggs 

 were placed among hens that did not reveal any evidence of infection according 

 to the flock history and examination of their eggs. Doyle (27) found that the 

 disease was not transmitted from 50 naturally infected birds to 30 healthy birds 



