TUBERCULOINFECTION OF MAN THROUGH ANIMALS 
AND ANIMAL PRODUCTS.* 
By A. O. Zwick, Ph.G., M.D., Cincinnati. 
Tuberculo-infection of man through animals and animal pro¬ 
ducts is essentially food transmission. At least I shall so take 
the subject which your president has done me the honor of pro¬ 
posing for my discussion. It is milk, cream, butter, cheese and 
meat, then, derived from tuberculous cattle that we must discuss, 
together with their effect upon the human economy when con¬ 
sumed, as they abundantly are, as articles of food. 
At the Veterinary Congress in Cassell, in 1903, Von Behring 
stated that the development of tuberculosis is always the result of 
infection in childhood, which in the great majority of cases is 
caused by the ingestion of milk from tuberculous cows. We now 
know that this view is much too sweeping, and finds contradiction 
in a mass of clinical and experimental data since accumulated 
bearing on this point. 
It is, indeed, as untenable as the opposite view, advanced by 
Robert Koch: “ That tubercle bacilli of bovine origin are entirely 
innocuous to man.” Since the astounding communications of 
these two men, the many, many investigations that have been 
carried on in various countries have abundantly proven that the 
human animal, particularly during early childhood, is capable of 
contracting bovine tuberculosis through the digestive tract, and 
probably through the tonsils. In J. B. Murphy’s laboratory I 
examined numerous tonsils, removed on account of disease, and 
found over 50 per cent, of them to be tuberculous. In fact, at 
every period of his existence man, particularly on manifold, re¬ 
peated or continuous exposure, is subject to tubercular infection, 
and the most important factor in the spread of tuberculosis is 
* Reprinted from Year Book, 1912-13, Ohio State Veterinary Medical Association. 
Read before said Association at Columbus, January, 1912. 
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