420 DISEASES OF CATTLE:" 



mortality of human beings from this disease, often amounting to 10 

 to 14 per cent, has raised the question in all civilized countries as 

 to how far animal, and especially bovine, tuberculosis was to blame 

 for this high mortality. The medical and veterinary professions have 

 approached this problem with equal zeal, and much has come to light 

 within recent years which enables us to come to some conclusion. If 

 this disease is transmitted from animals to man, how does the trans- 

 mission take place? As comparatively few people come in direct 

 contact with tuberculous cattle, it must be either through the meat, ' 

 the milk, the butter, the cheese, or through all of these products that 

 the virus enters the human body. The question has thus narrowed 

 itself down to the food products furnished by cattle. 



It has become a very urgent question, especially in the poorer coun- 

 tries of Europe, whether all flesh from tuberculous animals is unfit for 

 human food. It is argued there that if it can be shown that in the 

 majority of cases of. tuberculosis the bones and the muscular system 

 are free from infection, there is no reason why the meat should not 

 be put on sale under certain restrictions. The question may be 

 resolved' into two divisions: (1) How frequently does the disease 

 invade those parts of the body which are used as food? (2) When the 

 disease process is manifestly restricted to the internal organs do 

 tubercle bacilli circulate in the blood and lymph? and can they be 

 detected in the muscular tissue? 



(1) Disease of the bones is not unknown, although very rare. 

 According to Walley it appears chiefly in the spongy bones of the 

 head and backbone and in the long bonea of the limbs. Occasionally 

 the ends of the bones, where they are covered by the synovial mem- 

 brane of the joints, are dotted with tubercles. The muscular system 

 itself is very rarely the seat of tubercular deposits, although the 

 lymphatic glands lying near and among the muscles may be not infre- 

 quently diseased. 



(2) Whether tubercle bacilli are found in muscle juice independent 

 of any tubercular deposits is a question which must be approached 

 experimentally. There is on record a great variety of opinions on 

 this matter, some authorities considering all flesh from tuberculous 

 animals unfit for food, while others hold a contrary view. Experi- 

 ments have shown that in rare cases the flesh of tuberculous cattle 

 contains a small number of tubercle bacilli. In Germany the flesh of 

 animals in which the disease is just beginning, or in which it is 

 restricted to one or more related organs, is not rejected. When, 

 however, the disease has affected the muscles, or bones, or lymphatic 

 glands situated on or between them, the flesh is condemned as unfit 

 and dangerous. Animals are also rejected in which it is evident, 

 from the general distribution of tubercles throughout the various 

 organs, that the bacilli have been distributed by the blood and may 

 have been carried into the muscular system (generalized tuberculosis). 



