CHAPTER XXI 

 TUBERCULOSIS 



Tuberculosis is one of the most important communicable 

 diseases of both man and domestic animals. In the lan-r 

 it is of both economic and sanitary importance, since, as 

 noted in the spread of diseases by means of foods, a portion 

 of the tuberculosis occurring in man is due to the organism 

 from bovine sources. Statistics show that one seventh of 

 all deaths of human beings are due to tuberculosis, and 

 that one third of the mortality occurring between the ages 

 of twenty and forty-five, the productive period of life, is 

 caused by the tubercle bacillus. 



Animals affected. All of the domestic animals may be 

 affected, but the disease is most prevalent among cattle, 

 hogs and fowls. The ottfer domestic animals are rarely af- 

 fected. Besides the domestic animals, a large number of 

 wild animals ,-ire also susceptible. There is probably little 

 or no opportunity for wild animals to come in contact with 

 the organism in nature, but when placed in captivity where 

 there is opportunity for infection, the disease makes rapid 

 strides. It is the chief cause of death of monkeys, caged 

 animals, and birds in zoological gardens. In the London 

 zoological garden 30 per cent, of the birds that died wen 1 

 found to have tuberculosis. A disease caused by an organ- 

 ism belonging to the same group as the tubercle bacillus 

 produces what has been termed tuberculosis in some of the 

 cold-blooded animals. 



Distribution. Within very recent times the commerce 

 in domestic animals and their products and in cultivated 



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