CHAPTER VIII 
AVIAN TUBERCULOSIS 
Characterization. Avian tuberculosis constitutes an affection 
closely related to the same disease in mammals, characterized by the 
development of tubercles principally in the visceral organs. 
Poultrymen refer to the disease as spotted liver, liver complaint, 
rheumatism, or describe the birds as going light. 
Species affected. A considerable number of domesticated and 
wild birds are affected. The disease has been observed in the 
fowl, guinea-fowl, peafowl, turkey, duck, goose, swan, pigeon, os- 
trich, parrot, canary, pheasant, sparrow, and in a large number of 
species of wild birds kept in zoological gardens. 
Etiology. Typical strains of the avian variety of B. tubercu- 
losis possess characteristics enabling them to be differentiated from 
the human and bovine varieties. Avian bacilli are more readily 
isolated and cultivated in pure culture, than are the mammalian 
varieties. The avian organisms are somewhat shorter and stain 
more evenly than those of the mammalian variety. While the 
guinea pig is most susceptible to mammalian strains, inoculation 
with avian material may result in emaciation with no visible lesions, 
or in relatively slight lesions of a non-progressive character. When 
lesions are not visible after inoculation, it does not preclude the 
possibility that tubercle bacilli may be present and demonstrable 
microscopically, or culturally, or by further inoculation of the tis- 
sue into other guinea pigs. 
The transmissibility of avian tuberculosis to mammals and vice 
versa is of interest in connection with the control of the disease. 
As a general rule, fowls are not susceptible to the human and bo- 
vine varieties. Experimental evidence exists to show that calves 
may be infected by injections of avian tubercle bacilli, and that 
fowls have been artificially infected with tubercle bacilli of mam- 
malian origin. The majority of experiments to test this trans- 
mission have given negative results. In view of these findings, 
the simultaneous occurrence of tuberculosis in cattle or man, and 
in fowls exposed to infection from them, has slight value as evi- 
dence of transmission. All three varieties of the disease are so 
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