CHAPTEE VII 



TUBERCULOSIS OF THE COW IN EELATION TO HUMAN DISEASE 



By far the most important disease of cows is tuberculosis. 

 This disease as it exists in cows demands very careful con- 

 sideration on account of its wide prevalence, the frequency 

 with which the bacilli of the disease gain access to milk, and 

 because the disease can be transmitted to man through the 

 cow. The available literature is enormous, and the different 

 aspects of the problem numerous. An attempt has been 

 made to treat the subject with a due regard to the relative 

 importance of the different parts of the question. The ad- 

 ministrative control of the disease and the prevention of 

 infection to man is considered in Chapter XVIII. 



The Peevalence oe Bovine Tuberculosis 



The very extensive investigations which have been carried 

 out have shown that tuberculosis of cattle is extremely pre- 

 valent in most parts of the civilised world. The prevalence 

 varies greatly from a few small areas of infection up to a 

 condition affecting more than half the number of cows. In 

 a few places, such as the Channel Islands, the disease is un- 

 known in cows, but these cows readily become attacked when 

 they remove to an infected area. 



The extent to which tuberculosis is prevalent in cows can 

 only be determined by the use of tuberculin.. Writing in 

 1901, and basing his figures upon the tuberculin test. Dollar^ 

 remarks that Hunting, who examined 4000 English cattle, 

 found 20 per cent tuberculous, and quotes figures from other 

 countries giving a percentage for Denmark of 31, Sweden 



1 Trans. British Congress on Tuberculosis, 1901, vol. iv. p. 44. 

 125 



