Chapter XVII 



CHOLERA AND PLAGUE 

 CHOLERA 



Prevalence Asiatic cholera occurs in the 

 form of epidemics which follow the paths of 

 human traffic, spread quickly over wide areas, 

 and kill from 25 to 50 per cent of those affected. 

 No disease showing these features and, at the 

 same time, presenting a definite tendency to epi- 

 demic distribution, appeared in the civilized 

 world before the beginning of the nineteenth cen- 

 tury. Since then it has repeatedly encircled the 

 earth. Scarcely a country has escaped. All 

 such regions as are reached from India by a 

 long sea trip, such as Australia, Cape Colony 

 and the Unfrequented regions of the Arctic Zone, 

 remain free. The origin of cholera epidemics 

 has always been India its real home and 

 more persistently the lowlands of Bengal, with 

 Calcutta for the chief city. 



Vaccination Attempts to protect human be- 

 ings against cholera by prophylactic vaccina- 

 tion were made as early as 1885 by Ferran, a 



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