Contamination of Milk. 39 



Tuberculosis of the cow. As will be seen in a subse- 

 quent chapter, the tubercle germs may be given off from 

 the body of the diseased animal in the "open" stage of 

 the disease. They may come from the lungs, intes- 

 tines, and udder. Leaving the body from any of these 

 sources they may reach the milk. In tuberculosis of 

 the lungs the cow coughs up material from these or- 

 gans and swallows it. It is digested, but the tubercle 

 bacteria it contains pass off from the body in the ma- 

 nure. When the disease affects the intestines, the ma- 

 nure also contains the tubercle organisms. 



The bacteria are carried into 'the milk with the ma- 

 nure aird barn-dust. The udder is often affected by the 

 disease. In this case the milk is certain to contain 

 large numbers of the tubercle organisms, although it 

 may be perfectly normal in appearance and taste. 



Milk containing tubercle bacilli is often a means of 

 producing the disease in man, especially is this true 

 in the case of children, who use larger quantities of 

 milk than do adults and who seem to acquire tubercu- 

 losis by way of the intestinal tract more easily than 

 does the adult. If milk containing tubercle bacilli is 

 fed to calves and hogs, they are certain to be infected. 



In order to be certain that the milk does not contain 

 any tubercle bacilli it must have come from healthy 

 animals. Many tuberculous cows may give milk which 

 is perfectly healthful, but sooner or later the milk of 

 such animals is certain to contain the organisms of the 

 disease. No one can tell when this condition obtains, 

 hence the only safe way is to reject all diseased animals 

 from the dairy herd. 



Miscellaneous diseases of the cow. Certain other 

 diseases may be acquired by man from cattle through 



