FOODS AND PUBLIC HEALTH 3 



bulletin, except for one or two personal experiences used for illustration. 

 The information presented is taken purposely from the writings of rec- 

 ognized authorities in the scientific fields represented. A list of references 

 will be found at the end of the bulletin for the use of readers who may 

 want to verify statements made, or to read further about any of the 

 topics discussed. 



DISEASES SPREAD BY MILK 



Of all foods, market milk is perhaps the most common carrier of in- 

 fectious diseases. The importance of this fact becomes more apparent 

 when one stops to think that milk is the essential food of young children, 

 and is a substantial item in the diet of most people throughout their lives. 

 Tuberculosis, typhoid fever, scarlet fever, septic sore throat, and undulant 

 fever are diseases commonly spread by milk. There are others less im- 

 portant or less common that will not be discussed in this bulletin. 



Tuberculosis 



Cattle easily become infected with tuberculosis, and it is highly prob- 

 able that many cases of tuberculosis, especially in children, could be 

 attributed to the milk of tuberculous cows (2). Tuberculosis in children 

 frequently infects parts of the body other than the lungs. The infection 

 is often found in glands, a fact which strengthens the opinion that milk 

 may be a source of the disease. Many medical authorities l^elieve that 

 the germs can pass from the intestines into the glands, by way of the 

 lymphatic circulation, and eventually reach the lungs. Tuberculosis de- 

 velops slowly in the body, so naturally there are no epidemics such as 

 occur with typhoid fever, septic sore throat, diphtheria, and scarle: fever. 



It is not difficult to detect tuberculosis in dairy herds. The presence 

 of the germs in milk can be determined by laboratory tests, but the most 

 usual method is to apply the tuberculin test to cattle. The nature of 

 this test will not be taken up in this bulletin. All dairy farmers are famil- 

 iar with it. The use of the tuberculin test makes it possible to free dairy 

 herds of cattle that have tuberculosis. The result is of doub'e value — it 

 benefits both the dairy farmer and the consuming public. Since the be- 

 ginning of the century, tuberculin-testing programs over the United States 

 have produced a marked improvement in the health of dairy herds and 

 have decreased measurably the financial loss from the disposal of tuber- 

 culous animals. Over the same period, the prevalence of human tuber- 

 culosis, and the accompanying death rate from the disease, have decreased 

 markedly in this country; and undoubtedly a considerable part of the 

 credit for this improvement must be given to the eradication of tuber- 

 culosis from dairy herds. Goats are not often infected with tuberculosis, 

 and their milk is relatively safe in that respect. This appears to be due 

 to the way in which the animals are handled, rather than to their im- 

 munity to the disease, because goats can be infected with tuberculosis (3). 



Typhoid Fever 



Typhoid fever is a disease that is likely to break out in explosive epi- 

 demics, although isolated cases frequently occur. Epidemics of the dis- 

 ease usually are traced to water supplies or to milk supplies. Water 

 sanitation is a large subject in itself, and should be treated separately, 



