256 SPIRILLUM CHOLERA ASIATICS. 



Pathogenesis : Cholera is pathogenic for man only. The 

 disease is endemic in India, and all epidemics of cholera have 

 had their origin in that country. The habits of the Hindoos 

 and their religious customs are largely responsible for the 

 constant presence of this disease. Infection follows inges- 

 tion of the germ in either water or food. The disease is 

 probably never conveyed through the air, because the bacillus 

 succumbs so rapidly to desiccation. Furthermore, the germ 

 must find its way to the intestinal tract before the disease will 

 develop. It is possible that small numbers of the germ 

 may be swallowed with impunity ; but it is more probable, 

 in view of its feeble resistance to the mineral acids, that 

 there must be some abnormal condition of the stomach which 

 is accompanied by a diminution in the secretion of hydro- 

 chloric acid or its total suppression, before infection can take 

 place. 



The cholera germ multiplies rapidly in the intestinal tract, 

 with elaboration of its toxin, which is absorbed and gives 

 rise to the symptoms of the disease. All the pathologic lesions 

 of cholera are due to this absorption of the toxin. 



Infection : The stools of the cholera patient are the infecting 

 medium, and soiled clothing or bed-linen is the usual means 

 of conveying the disease to others. Emptying the dejecta 

 into a sewer or depositing them on the ground without disin- 

 fecting them, causes contamination of the water-supply if the 

 sewerage is imperfect or when the water is obtained from 

 wells or from small streams or creeks. 



Insects which feed on the dejecta may carry the germs and 

 deposit them on food or in water many miles distant from the 

 original source of the disease. 



Pollution of the water-supply is by far the most common 

 and also the most dangerous source of infection. The famous 

 epidemic of cholera in London had its origin in the pollution 

 by cholera dejecta of the water-supply derived from the Broad 

 Street pump. Nearly every individual using this water be- 

 came infected with the disease. 



In India the natives bathe in the river Ganges as a religious 

 practice, and the dead are also buried in the river no matter 

 what the cause of death may have been. At those times of 



