480 IOWA DEPARTMENT OP AGRICULTURE 
and gradually to eliminate the disease. At the end of six or eight years 
he should have a herd of cattle free from tuberculosis and be prepared to 
destroy all of those which have reacted. 
BOVIXE TUBEKCULOSIS AND PUBLIC HEALTH. 
The increasing amount of evidence point to the identity of human and 
animal tuberculosis, combined with the extraordinary mortality of hu- 
man 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 ani- 
mals to man, how does the transmission 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 countries 
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 re- 
stricted 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. Ac- 
coding to Walley it appears chiefly in the spongy bones of the head and 
backbone and in the long bones of the limbs. Occasionally the ends of 
the bones, where they are covered by the synovial membrane of the 
joints, are dotted with tubercles. The muscular system itself is very 
rarely the seat of tubercular deposits, although the Imphatic glands lying 
near and among the muscles may be not infrequently diseased. 
(2) Whether tubercle bacilli are found in muscle juice independent 
of any tubercular deposits is a question which must be approached ex- 
perimentally. 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. Experiments 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 re- 
lated 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 through- 
out the various organs, that the bacilli have been distributed by the 
blood and may have been carried into the muscular system (generalized 
tuberculosis). 
