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CHARLES HERRMAN 



disease spread among the inhabitants of the islands, so that nearly all were 

 infected, but in spite of the rather unfavorable climatic conditions of the 

 tropics for foreigners very few died, among the half-castes a small per cent 

 of deaths occurred, but among the natives the mortality was from 15 to 25 

 per cent." 



A similar high mortality has often been noted when measles has been 

 introduced into an isolated community in which the disease had not occurred 



Chart 11. Mortality per 100,000 Population from Pneumonia, Influenza, Chronic 

 Heart Disease, and Cancer, New York City, 1913 to 1923 



for one or more generations. On the other hand when a disease has been 

 common, for example malaria among the Negroes of Africa and cholera 

 among the natives of India, non-resistant strains have been eliminated, 

 so that the native population enjoys a relative immunity as against foreign 

 immigrants. 



A very large part of the remarkable reduction in the mortality from 

 diphtheria is undoubtedly due to the introduction of active immunization 

 against this disease (chart 12) but in the case of measles, scarlet fever and 

 whooping cough (chart 13), we have as yet no certain specific treatment. 



