472 INFECTION AND IMMUNITY. 



instance it was cultivated from the water of an 

 aquarium after several months. Its life is short in 

 the presence of putrefactive bacteria and rapidly- 

 growing saprophytes, dying in sewer water in from 

 twenty-four to thirty hours (Koch). Because of 

 the large overgrowth of other organisms, the vibrio 

 can rarely be cultivated from the stools later than 

 from one to three days after death. Its life in and 

 on foods depends on the reaction (alkalinity is 

 favorable), and on the presence or absence of 

 moisture. It lives longer in sterilized milk (ten 

 days) than in that which contains other micro-or- 

 ganisms. 

 infection Infection develops in the small intestines fol- 



Atrinm and . . . , . _ . , 



ina- lowing mgestion of the organisms. Infection by 

 way of the lungs or through wounds does not take 

 place. In the patient the living vibrio occurs only 

 in the intestines, and it is excreted only with the 

 feces. So far as known, it has no normal habitat 

 outside the body, although a stream or other water 

 supply may contain the vibrio over a long period 

 through constant reinfection of the water. This 

 can only occur, directly or indirectly, through the 

 stools of patients. The washing of soiled linen or 

 bathing in water which is used for drinking and 

 other household purposes have caused outbreaks of 

 cholera. The water supply of a city may be in- 

 fected by the discharges of patients who are con- 

 fined to a ship. Convalescents may retain virulent 

 organisms in their stools for forty-eight days 

 (Kolle), and, as stated, healthy persons who are 

 insusceptible to cholera and who have resided in 

 an infected district may carry virulent vibrios in 

 their intestines. These conditions have contrib- 

 uted to the futility which, to a large degree, has 



