, DISEASES CAUSED BY INFECTED MILK 105 



for butter, may be free from the danger in question. Oleo- 

 margarine may become infected in two ways: by fat de- 

 rived from tuberculous animals, or by butter and sour milk 

 that sometimes enter into its composition. Morgenroth 

 examined twenty samples of oleomargarine purchased in 

 the open market and found that nine of them contained 

 virulent tubercle bacilli. 



It is perfectly plain, therefore, that cream, ice cream, 

 butter, cheese, and other milk products are a source of 

 danger to man so far as tuberculosis is concerned, for these 

 articles not only contain tubercle bacilli, but some of them 

 contain the infection in concentrated form. 



The 'prevention of bovine tuberculosis. There are two 

 clearly defined methods by which man may protect himself 

 from the dangers of bovine tuberculosis. One is the elimin- 

 ation of tuberculosis from cattle: the other is pasteuriza- 

 tion. The elimination of bovine tuberculosis in cattle is a 

 large undertaking, but may successfully be accomplished 

 in isolated herds, in a reasonably short time, through the 

 aid of the tuberculin test, and by the information derived 

 from physical examination. Until the milk supply is de- 

 rived from tuberculin-tested cows or from milch cows 

 known to be free of infection, our only protection is pas- 

 teurization. A temperature of 60° C. (140° F.) for twenty 

 minutes kills tubercle bacilli and renders them entirely 

 harmless. 



The bovine tubercle bacillus is transmitted from cattle 

 to man, in the great majority of cases, through milk. So 

 infrequently does it come to us through the meat or other 

 beef products that we may almost ignore all, except milk, 

 from a public health standpoint. Tuberculosis of the 

 muscles is very rare; furthermore, meat is usually cooked. 

 The heat of cooking gives us a similar protection in eating 

 tuberculous liver or other glands. Finally, the system of 

 meat inspection which is carried on in this country is an 

 additional safeguard. 



