CHAPTER III. 



EPIDEMIC DISEASES TRANSMITTED BY MILK. 



Transmission of diseases of man by milk. Milk traffic as 

 now constituted, offers a particularly favorable channel for 

 the transmission of certain diseases of man. The close con- 

 tact of human beings incident to the handling of milk at the 

 producing dairies, coupled with the general lack of observance 

 of aseptic precautions in the work, offer frequent opportunities 

 for contamination of the product. Milk offers conditions that 

 are not unfavorable to the bacteria of typhoid fever and diph- 

 theria, and they may even multiply therein. The unrecog- 

 nized virus of scarlet fever likewise finds conditions favorable. 



The wide use of milk among households gives opportunity 

 for very broad distribution of infection through milk. The 

 output of a dairy. may not go to the same consumers from day 

 to day, so the field for the possible infliction of damage by a 

 dairy is yet more widened. 



Character of milk-borne epidemics. The large well-marked 

 epidemics borne by milk are characterized by the almost sim- 

 ultaneous appearance of cases among patrons of the milk route. 

 Variations occur, due to individual idiosyncrasy with respect 

 to the incubation period of the disease. As likely as not the 

 primary cases, attributable to the milk, will cease to occur as 

 suddenly as they began.. Later, there will be observed second- 

 ary cases among members of the same or different households. 

 The causative relation of milk stands out most clearly in out- 

 breaks derived entirely from milk, and not complicated by the 

 concurrent presence of the disease due to other quite different 

 channels of dissemination (18). 



Very thorough study of reported cases of typhoid and diph- 

 theria in a city, with reference to the milk supply, have led to 

 the conclusion that milk is responsible for many isolated cases 



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