ERADICATION OF PULLORUM DISEASE 1931-32 55 



by inflammatory changes, and this suggests that the organisms may have entered 

 the conjunctiva or associated structures. In birds exposed to the organism by 

 the ocular route, agglutinins appeared in the blood stream around the seventh 

 day, whereas in those birds exposed by oral administration, agglutinins ap- 

 peared around the tenth day. In all birds exposed by the ocular route agglutinins 

 were produced, while in the orally ex-posed group some birds did not produce 

 agglutinins. Gross lesions were more common and the percentage of isolation 

 of S. pullonim was higher in the ocular ex-posed group. The occurrence of infec- 

 tion through the ocular route appears to be possible under natural conditions. 

 Contaminated litter, feed, and droppings coming in contact with the eye might 

 lead to the establishment of infection in the body. It is possible that this avenue 

 of infection might play a role in the dissemination of the disease among chicks 

 in the incubator, especially in the forced draft type where hatching debris is more 

 or less in constant circulation and in that way comes in contact with the eye of 

 the chick. 



While agglutinins appeared earlier in the birds ex-posed through the cloaca 

 than in the birds exposed through the skin incision, yet the persistency and the 

 strength of their titers were not as great. The infection did not appear to be as 

 well established in the group ex-posed through the cloaca. Exposure to infection 

 through these channels demonstrates that even though the organism did not 

 become permanently established in the body, agglutinins existed to indicate 

 that transient infection had been present. Also it may be possible that even 

 through the use of the most careful and thorough necropsy technique, the re- 

 covery of the organism from some reacting birds may meet with failure. Under 

 natural conditions with suitable environment, it appears possible that birds 

 might contract the disease through these channels. 



In comparing the four different avenues as to the ease with which the organ- 

 ism may enter the body, no direct comparisons can be made since the different 

 avenues were not all tested at the same time and under identical conditions. 

 However, the results suggest that birds might be more subject to contracting 

 the disease, if ex-posed through the eye route than through the other avenues 

 studied. Infection appears to occur less readily w-hen the organism is adminis- 

 tered through the oral route than through the other avenues. 



Conclusions 



1. Pullorum disease can be reproduced in chickens by dropping a suspen- 

 sion of the organisms on the conjunctiva, into an incision in the skin of the 

 plantar surface of the foot, into the cloaca, and by oral administration. 



2. The introduction of organisms through the oral route did not appear 

 as successful in reproducing the disease as the other avenues of exposure which 

 were studied. 



3. It appears possible that pullorum disease dissemination may occur through 

 all these avenues under natural conditions where a suitable environment exists. 



OBSERVATIONS CONCERNING DIAGNOSTIC TESTS FOR 

 PULLORUM DISEASE 



Since pullorum disease is inherent in character and may exist in apparently 

 normal birds, the fact has become recognized, as supported by an abundance of 

 data, that the disease can be eradicated by detecting the infected adult birds. 

 Various methods of detecting such birds have been investigated. According to 



