MILK-BORNE INFECTIONS 441 



of very recent date, and in many cases the epidemics have been 

 attributed to milk. EarUer reports, originating chiefly in Eng- 

 land, traced sore throat outbreaks to the milk of herds in which 

 mastitis was found to exist. Therefore it was believed that 

 mastitis was the cause of sore throat in man. However, the 

 evidence is not entirely convincing, and the fact that mastitis is 

 wide-spread would lead to the assumption that sore throat is 

 much more common among milk drinkers than it actually is. 

 Furthermore, epidemics of sore throat appear chiefly in winter 

 and early spring, while mastitis occurs at all seasons without 

 distinction. When epidemics of sore throat occur and are traced 

 to milk-supplies, it is not difficult to find some cases of mastitis 

 in suspected herds, since the disease is common; so common, in 

 fact, that some authorities claim there is no herd of cows entirely 

 free from it. 



That milk has been the vehicle of the virus of septic sore 

 throat has been clearly shown, although contact infection fre- 

 quently plays an important role. StiU the true source of infec- 

 tion has rarely been discovered. Winslow has reported an ex- 

 tensive epidemic in Boston and some neighboring cities, and has 

 traced it definitely to a milk-supply, but in casting about for a 

 source of infection of the milk he failed to find conclusive evidence, 

 and surmised the presence of a human carrier in the dairy. The 

 incriminated supply was one of the best ones in the city; excep- 

 tional care was exercised to guard the milk against infection; and 

 constant scientific control of the milk at all stages of production 

 and during handling was exercised. No disease among the cattle 

 could be detected. In an epidemic in Chicago in 1911-12, which 

 was traced to a milk-supply, the cases occurred chiefly in limited 

 districts, and the writer was able to locate a carrier in the dairy 

 who seemed responsible for communicating the infection. It 

 was there stated that "the epidemic may be attributed to a par- 

 tial infection of the milk-supply rather than to infection of the 

 whole." As a matter of fact, the infection gained access to the 

 milk after pasteurization. The man who handled the bottles 

 was suffering from a severe case of septic sore throat, and by 

 coughing, sneezing, etc., might have infected the bottles inter- 

 mittently. This explains the occurrence of cases in groups rather 

 than over the whole territory covered by the supply. 



Mastitis is usually caused by streptococci, and investigators 

 have concluded that the streptococcus causing septic sore throat 

 in human beings is derived from mastitis. Streptococci may pro- 

 duce a great variety of pathologic conditions in man, and it is con- 

 ceivable that the same strain which is the cause of mastitis in cows 

 may adapt itself in such manner as to produce sore throat in man. 



