CONSTITUTIONAL DISEASES 143 



TUBERCULOSIS 



This is a disease of great importance to the poultrynian, not 

 only on account of its destructiveness to his flock, but also 

 on account of its relation to the health of himself and family ; 

 for wliile fowls are not very likely to contract tuberculosis 

 from domestic animals or from man, yet fowls that have the 

 disease are a serious menace to the other animals on the farm 

 as well as to the poultryman and his family. 



Cause. — The Bacillus tuberculosis, which was discovered by 

 Koch in 1882, is the cause of this disease. There are four prin- 

 cipal types of this organism. The one most commonly in- 

 fecting man is designated as the human type. The one pe- 

 culiar to cattle is designated as the bovine type ; and the one 

 peculiar to fowls the avian type ; and there is still another type 

 of the tubercle bacillus which affects fish and other cold-blood- 

 ed animals. 



While there are some differences in the shape of the organ- 

 isms grow^n for a considerable time in the various animals and 

 some differences (biochemically) when grown in artificial 

 media after isolation, yet the type peculiar to any of the 

 warm-blooded animals will grow in any of the other warm- 

 blooded animals, that is, the types are interchangeable, which 

 means that the bovine type may cause tuberculosis in man and 

 the human type may cause tuberculosis in birds, etc. Most 

 authors consider that while the chicken has considerable re- 

 sistance to the human type, it will and does become infected 

 by this type. 



It has been found that a large percentage of hogs fed swill 

 from houses where tuberculous persons have expectorated into 

 it. become tuberculous, and when slaughtered, there is a con- 

 siderable loss from condemnation of those badly affected. 

 (Busman.) 



Tuberculosis among chickens is rare in some portions, and 

 is very common in other localitie.s in the United States. Al- 

 though it is widespread throughout the United States and 

 Canada, it was first reported in this country in 1900 and 

 received but slight attention until 1908. It also occurs in tur- 

 keys, pigeons and pheasants, and two cases in wild geese were 

 reported at the Ontario Agricultural College. The loss from 

 this disease seems to be increasing. 



VanEs and Schalk have produced tuberculosis experiment- 

 ally in twelve sparrows by feeding them chopped tuberculous 

 liver of a hen. 



Mode of Hpread. — In the progi-ess of tuberculosis of chick- 

 ens at times there is noted a diarrhea. In these cases there 

 are tuberculous ulcers of the mucous lining of the intestinal 



