EXTENT AND IMPORTANCE OF THIS INDUSTRY 33 



it is not known whether it may or may not multiply ra 

 milk. 



Bovine Tuberculosis. — Investigations have shown that 

 tuberculosis of the bovine type is common in children. The 

 infection may be caused by the ingestion of meat from 

 tubercular animals; it may be caused by inhaling infected 

 air; and in all probability it may be caused by drinking 

 milk from tuberculous cows. Indeed, when we consider 

 that meat is usually cooked before being eaten, while milk 

 is used raw, and that children consume a relatively small 

 amount of meat and a very large quantity of milk, we 

 cannot but conclude that milk is the main food that dis- 

 seminates this disease among children. 



In milk examined for the presence of tubercle bacilli, 

 an average of 5 per cent of all samples examined in various 

 cities in this country contained tubercle organisms viru- 

 lent for guinea pigs. In many places the percentage was 

 much higher. In Philadelphia, 14.6 per cent of the samples 

 of milk examined were tuberculous. Hess found 16 per 

 cent of the milk supply of New York City to contain viru- 

 lent tubercle bacilli. 



Butter and cheese are of much less importance in this 

 respect, but it has been shown by Mohler, Washburn, 

 Rogers and Doane, that tubercle bacilH retain their viru- 

 lence for six months in butter, and for eight months in 

 cheese. 



Parke of New York City has found bovine tubercle 

 bacilli in 26 per cent of the cases of tuberculosis in children 

 under 5 years of age. 



Of the fatal cases of tuberculosis among children inves- 

 tigated by the German and British tuberculosis commis- 

 sions, about one-third was foimd to be due to the bovine 

 type of bacillus. 



