840 PATHOGENIC MICROORGANISMS 



washed in a stream with distribution of the disease further down- 

 stream in other villages, but not in any of the villages higher up 

 the river. It is also probable that in countries such as India, the 

 custom of throwing dead bodies into rivers may contribute ma- 

 terially to the constant presence of the disease. 



In endemic centers, it is more than likely that the cholera carrier 

 is a very important factor of distribution. The existence of the 

 carrier is proven beyond doubt, and, as in typhoid, individuals may 

 remain carriers for very long periods. Greig has shown that the 

 organisms may live in the gall-bladders of human beings as in the 

 typhoid carrier state. McLaughlin 12 has found as many as 7 per 

 cent of the population of an infected district to be cholera carriers. 



Again, as in typhoid, distribution of fecal material to food by 

 flies probably plays a very important role, and according to Barber 

 the organisms may live for some time in the intestines in such 

 insects as cockroaches. Whether or not domestic animals can act 

 as distributers of the organisms is uncertain. Violle quotes Haffkine 

 as stating that he had found the spirilla in the intestines of cattle, 

 and that they were found by Hahn in the intestines of cows during 

 cholera epidemics. The importance of this, however, is still quite 

 uncertain. 



In nature the cholera spirilla may, under favorable conditions, 

 remain alive for considerable periods. In drinking water they have 

 been found alive after several days and they may remain alive for 

 weeks in water supplies. From the investigations of Wernieke, 18 

 Shirnoff 14 and others it would appear that under favorable condi- 

 tions the spirilla may remain alive in river water and other natural 

 waters for weeks or even months. In milk and other foods, the 

 longevity of the cholera spirilla seems to depend particularly upon 

 the nature and numbers of other bacteria present and on the produc- 

 tion of an acid reaction. In cholera stools they will remain alive 

 until considerable putrefaction has taken place and, therefore, may 

 be assumed under favorable conditions to live at least one day, 

 or perhaps three days or longer. In cold weather when bacterial 

 growth is more or less inhibited, they may remain alive much longer 

 than this. 



12 McLaughlin, quoted from Eosenau 's Preventive Medicine and Hygiene, D. 

 Appleton and Co., New York and London, 1921. 



13 Werniclce, Hyg. Eundschau, 1895. 

 u Shirnoff, Cent. f. Bakt., 41, 1908. 



