IO4 PRACTICAL DAIRY BACTERIOLOGY 



some have believed that the cow herself may suffer from the 

 disease and affect the milk through the udder. No such in- 

 stances are positively known, but it is known that secondary 

 infection is possible. It is well known that convalescents from 

 this disease carry active germs in their throats for some time 

 after they appear perfectly recovered. (Fig. 40.) Such persons 

 would naturally be allowed to return to work in the dairy, and 

 the chances of infection in such instances are very great. Al- 

 though such instances are not common they have been known; 

 and the milk supply must be looked upon as one of the sources 

 of the distribution of this disease. 1 



Scarlet Fever. Scarlet fever has almost exactly the same 

 relation to milk as diphtheria. We have as yet no proof that 

 the disease may come from the cow, although one epidemic of a 

 somewhat similar disease has been attributed to diseased cows 

 in Herndon, England, and other cases have been reported of a 

 similar nature. There is fairly good evidence that the milk may 

 become infected by persons who have the disease or are re- 

 covering from it. When such persons have direct or indirect 

 contact with the dairy there is occasional opportunity for the 

 milk to become infected. The cause of this disease is as yet 

 unknown, but it is doubtless some living germ. At all events 

 those who subsequently consume such infected milk do some- 

 times contract the disease. A few epidemics have been traced 

 sufficiently to convince us that here is a positive source of 

 danger, though perhaps not a very great one. 



Asiatic Cholera is also transmitted by milk, but this is a matter 

 of no special significance in the United States. 



1 Davies. Jour, of Hyg., p. 338, 1901. 

 Klein. Cent. f. Bact., ii., p. 219, 1887. 

 Lee. Hyg. Rund., p. 227, 1900. 

 Tingvall. Hyg. Rund., p. 109, 1904. 



