HEALTH AND DISEASE 



433 



may be avoided by having priv- 

 ies and cesspools some distance 

 from the well and so placed 

 that they will drain away from 

 it. Wells should have a ce- 

 mented cap around the top so as 

 to keep out surface water, as 

 germs rarely live long more 

 than five feet below ground. 



Serious outbreaks of typhoid 

 have been traced to contami- 

 nated milk supplies. A case of 

 typhoid exists on a farm; the 

 sewage gets into the well from 

 which water is used for the 

 washing of milk cans. Typhoid 



germs thrive in milk. Thus the milkman spreads disease. The 

 diagram following illustrates a recent epidemic in Stamford, Conn., 

 which was traced to a farm on which was a person having typhoid. 



Growth of bacteria in a drop of impure 

 water allowed to run down a sterilized 

 culture in a dish. 



I) 



Cases of typhoid per 100,000 inhabitants before filtering water supply (solid) and 

 after (shaded) in A, Watertown, N.Y.; B, Albany, N.Y.; C, Lawrence, Mass,; 

 Z>, Cincinnati, Ohio. What is the effect of filtering the water supply ? 



HUNT. ES. BIO. 28 



