BACILLI OF THE COLON. 59 



fed the city reservoir; 1500 cases of typhoid occurred 

 in a remarkably short time. 



Wells are sometimes infected from privies, cis- 

 terns, and open cesspools when they are placed near a 

 well, or when the natural drainage of the soil-water is 

 in the direction of the well. Defective walls or cover- 

 ing that admit surface-water render the infection of 

 wells in this way more likely. 



Milk is an excellent culture medium, and typhoid 

 bacilli will grow readily in it. They gain entrance to 

 the milk by washing the milk cans or pails in infected 

 water, or from the hands of persons sick or but 

 recently recovered from the disease. Flies may also 

 carry the infection to milk. There have been some 

 185 epidemics of typhoid traced to milk. In 1903 a 

 milkman in Boston sick with typhoid spread the dis- 

 ease through the milk, causing an epidemic of over 

 400 cases. 



The infection may be spread by eating uncooked 

 vegetables that have been washed in infected water. 

 Oysters and clams, when they have been grown in 

 water contaminated with sewage, have been known to 

 carry the infection. Along the seaboard laws are now 

 in force that prohibit the cultivation of oysters in 

 water near the outlet of. sewers. The importance of 

 flies in the spread of typhoid has been recognized only 

 in the last ten years. When they come in contact with 

 typhoid patients, or with infected discharges, they 

 carry the bacilli on their bodies and deposit them on 

 foodstuffs. 



