MILK-BORNE INFECTIONS 437 



would be advantageous, but it should not be forgotten that milk 

 requires a great deal of handling by human beings, while water 

 is a product of nature that requires much less care. It seems 

 impossible to employ men for milk production who are surely 

 free from disease and who do not carry disease germs. The task 

 of a medical supervisor would be' enormous. Bacteriologic technic 

 is not yet sufficiently developed to infallibly locate all carriers. 

 Furthermore, the larger the milk-supply, the greater is the danger 

 of spreading infectious material, because the contaminated milk 

 is mixed with the balance of the supply. It is true that this proc- 

 ess also involves a proportionate dilution of the virus, but how far 

 this is a source of protection is problematic. Efficient dairy in- 

 spection, guided by bacteriologic control, which leads to cleanli- 

 ness in methods; exclusion of flies; thorough cleaning and steam- 

 ing of all utensils and bottles, and proper sealing of containers to 

 prevent tampering, may aid in the reduction of milk-borne dis- 

 ease. Medical examination of all employees and veterinary in- 

 spection of the cows also will help in obtaining the desired result. 

 But these safeguards are limited and uncertain owing to the 

 difficulties involved in their execution. Under modern conditions 

 there is but one remedy efficient pasteurization. 



The diseases which have been known to be disseminated through 

 milk may be divided into two classes, namely: 1, those which are 

 derived from human beings engaged in handling milk, and 2, 

 those which are derived from diseased cattle. To the first class 

 belong typhoid fever, dysentery, paratyphoid fever, diphtheria, 

 septic sore throat, human tuberculosis, Asiatic cholera, and 

 scarlet fever. To the second class belong bovine tuberculosis, 

 foot-and-mouth disease, mastitis or garget, contagious abortion, 

 anthrax, rabies, actinomycosis, botryomycosis, . cowpox, milk 

 sickness, and gastro-intestinal troubles. Malta fever, commonly 

 carried by goat's milk, also belongs to the second class. 



DISEASES DERIVED FROM HUMAN BEINGS 



Typhoid fever is one of the most important infections carried 

 through milk, and is communicated to milk through human agencies 

 only, since cows are not susceptible to the disease. The bacilli grow 

 well in milk if temperature conditions are favorable, but in properly 

 cooled milk there is little if any growth. The changes caused in 

 milk by Bacillus typhosus are slight and not noticeable to the 

 unaided senses. The amount of acid formed is too small to be 

 recognizable except by the use of chemical indicators, and some 

 strains of typhoid bacilli produce alkali after an initial acid pro- 

 duction, with the result that the acid is neutralized. Typhoid 



