256 BACTERIOLOGY FOR NURSES 



sand filtration before use. Throughout the period of the epidemic 

 houses situated on one side of a street and supplied with Hamburg 

 water developed many cases of cholera, while those on the other 

 side of the street receiving their supply from Altona remained 

 uninfected. 



Epidemics occasionally occur which are more difficult to trace 

 to their source. Cholera spirilla have been found in the feces of 

 healthy individuals and of people suffering from slight intestinal 

 disturbances. " Cholera carriers " therefore are a possible foci of 

 infection. Investigations have shown that the spirilla tend to 

 disappear from the feces in from four to fourteen days. They 

 have been known, however, to persist for sixty-nine days and 

 longer. Contact infection plays an important role where persons 

 live together under uncleanly conditions. The careless handling 

 of dejecta and soiled linen is especially liable to result in infection. 

 Haffkine, in India, found that sterilized milk if left in open jars 

 to which flies had access might become contaminated with cholera 

 organisms in a cholera-infected locality. 



Pathogenesis. Asiatic cholera appears to be a disease peculiar 

 to man ; none of the lower animals have been known to contract it 

 naturally. Intraperitoneal injections of the organisms into a 

 guinea pig may be speedily fatal, but intestinal lesions are rarely 

 seen. Koch succeeded in producing the disease in much the same 

 form as it appears in man by first neutralizing the gastric juice 

 with a solution of carbonate of soda and inhibiting peristalsis by 

 an injection of tincture of opium and then introducing a culture 

 of the cholera spirilla into the intestinal tract by means of a cath- 

 eter. Metchnikoff obtained similar results with new-born rabbits 

 by rubbing a small amount of culture on the teats of the mother 

 rabbit. 



In man the lesions are primarily intestinal. The short incuba- 

 tion period, which is usually one to two days and rarely over five, 

 is indicative of the rapid multiplication of the organisms once 

 they have gained entrance to the alimentary tract, and to the 

 production of a speedily effective toxin. The lower part of the 

 small intestine is the part most affected. Penetrating the surface 



