Infection of Milk. 65 



It has been a disputed question for some years 

 whether the organisms producing bovine and human 

 tuberculosis are identical or from the practical stand- 

 point, whether the bovine type of disease is transmitted 

 under natural conditions to man. The bacteriologist 

 can readily detect differences in appearance, in growth 

 of cultures, and in disease-producing properties be- 

 tween the two strains. Of the two, the bovine is much 

 the more virulent when inoculated into experimental 

 animals. In a considerable number of. cases, record 

 of accidental infection from cattle to man has been ob- 

 served. These have occurred in persons making post- 

 mortem examination on tuberculous animals, and the 

 tubercular nature of the wound proven by excision and 

 inoculation. 



More recently, since the agitation by Robert Koch of 

 Germany, a number of scientific commissions have 

 studied particularly the problem of transmission. It 

 is now estimated that perhaps seven per cent of the 

 tuberculosis in man is of bovine origin. This is almost 

 wholly confined to children. The portions of the body 

 that become diseased, when the infection has resulted 

 from the use of milk, are the glands of the neck and 

 of the abdomen. 



Manner of infection in man. In the main, the source 

 of the malady may be traced either to air infection or 

 to the food, if one disregards the comparatively small 

 number of cases of wound infection. Air is frequently 

 a medium by which the germ is transferred from one 

 person to another. The sputum is exceedingly rich in 

 tubercle bacilli and since this material is carelessly 

 distributed by tubercular people, the air of the cities, 

 5 



