SPIROCHETE GROUP 449 



Isolation and Culture. The organism has not been cultivated 

 upon artificial media. 



Pathogenesis. Experimental Evidence. Many birds may be 

 infected by inoculation, among them the goose, duck, fowl, guinea 

 fowl, turtle-dove, sparrow, and other birds; usually not the pigeon, 

 although there is disagreement on this point. The rabbit, white 

 mouse, guinea-pig, monkey, horse, and man are not susceptible. 

 Each of the various types described have usually showed the 

 greatest virulence for the species of bird from which it was originally 

 described, and many variations in virulence have been observed. 



f 



Fig. 198. Spirochaeta anserina (gaUinarum) . An agglutinated group from 

 the blood of a fowl (Xovy and Knapp, in " Journal of Infectious Diseases ") 



It is believed that transfer through the intermediary host is neces- 

 sary for the retention of virulence. 



Character of Disease and Lesions. The disease is characterized 

 as a true septicemia; Levaditi has shown that the organisms also 

 invade the intercellular spaces in various organs. The disease 

 runs an acute course, marked by fever. Young fowls may show 

 relapses, but the adults rarely. In this respect the disease differs 

 from that caused by Spirochceta obermeiei'i in man. The organisms 

 are present in the blood in great numbers during the crisis. They 

 rapidly disappear during convalescence. The mortality varies 



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