DISEASES COMMUNICABLE IN MILK 65 



amount of typhoid fever and minor intestinal disorders among the mid- 

 shipmen and the difficulty of getting contract milk that was produced 

 under fit sanitary conditions led to the establishment of a dairy with a 

 herd of 90 cows selected by the Bureau of Animal Industry. A new barn 

 was built and a determined and successful effort was made to keep flies 

 out of it. 



The Academy supply was first served the midshipmen on October 1, 

 1911, but a part of the contract supply was continued in use for 2 months. 

 The young men are in prime physical condition and their diet is con- 

 trolled, yet a remarkable reduction in absences from classes was obtained 

 when they were given the milk from the Academy herd. No other change 

 in the food was made and the authorities attribute the improvement 

 shown in Tables 28 and 29 solely to the improved milk supply. 



Diseases of Class II. The second class of diseases transmitted in 

 milk, is made up of certain infections derived from man and comprises 

 typhoid fever, paratyphoid fever, Asiatic cholera, diphtheria, scarlet fever, 

 and septic sore throat. Of all the diseases of this class it may be said 

 with assurance that the recorded number of milk-borne epidemics is 

 decidedly less than actually have occurred. This is partly because many 

 epidemics are never investigated, and partly because health officers and 

 others often do not regard epidemics which they have throttled to be of 

 sufficient general interest to write up. In other cases local pride and busi- 

 ness interests may keep outbreaks quiet. 



In very few instances has the specific disease germ been isolated from 

 the suspected milk. This is usually because the game is not worth the 

 candle; in most cases the bacteriological technique is tedious and uncer- 

 tain but of at least equal moment is the fact that whereas the milk sup- 

 ply is not apt to remain infected for more than a short time the incuba- 

 tion period of the disease may last several days or even 2 weeks so that 

 the disease germs disappear from the milk' before the contagion breaks 

 out. Then, in the case of scarlet fever, the specific organism is unknown. 

 So, epidemiological methods are chiefly relied on to detect sources of 

 infection and to nip budding epidemics. 



Typhoid Fever. Typhoid fever is a communicable disease that is 

 spread by direct contact and by infected water, milk, oysters and other 

 foods, and by flies. The relative importance of these several modes of 

 dissemination varies in different places but everywhere that it is consumed 

 raw, milk is more than likely to be an important factor in spreading the 

 disease. In some localities it may take first place as a disseminator; 

 this is apt to be so where other causes have been largely eliminated. 

 Thus in 1907 Harrington stated that in Massachusetts, where pure water 

 supplies are the rule, for the 2 years past, 14 out of 18 outbreaks of ty- 

 phoid fever were due to milk. 



Milk is a very common source of typhoid infection; Trask and a few 



