BACTERIA IN WATER AND MILK. 107 



dirt bacteria may be spread in milk. Many epidemics Diseases 



: , . ...... transmitted 



of scarlet fever, typhoid fever, measles, and diphtheria by miik 

 have been traced to infected milk. The infection is 

 introduced into' the milk at the dairy, usually by some- 

 one sick with the disease in question. 



The transmission of tuberculosis in the milk from 

 tuberculous cattle is believed to be of common occur- 

 rence, particularly among infants. The tubercle bacilli 

 may pass through the walls of the intestine without 

 causing any disease of the intestinal wall itself, and 

 lodge in the mesenteric lymphatic glands. They may 

 lie dormant for years and later on, when the resistance 

 is lowered by disease or by unsanitary conditions of 

 living, become active and cause tuberculosis in what- 

 ever organ or tissue they may have lodged. The milk 

 from cattle having tuberculosis of the udder is the 

 most dangerous; but even when the udder is healthy 

 and the disease located in other organs, the milk may 

 contain tubercle bacilli. Not only is the milk from 

 tuberculous cattle infectious, but also the products 

 butter and cheese made from the milk. From what 

 has been said, it is easy to- see the danger of using raw 

 cows' milk for infant feeding without positive assur- 

 ance that the cows have been tuberculin tested and are 

 free from tuberculosis. 



THE BACTERIA IN WATER. 



Water as it falls in the form of rain is free from 

 bacteria. It begins to be contaminated with bacteria 

 when it reaches the dust-laden air above the earth, and 



