HOW INSECTS AFFECT HEALTH IN RURAL DISTRICTS. 



INTRODUCTION. 



In very many parts of the country the farming population has to 

 contend with at least two diseases which are preventable. These are 

 malaria and typhoid fever. Both of these diseases are transferred 

 or may be transferred by insects — malaria by certain mosquitoes and 

 typhoid fever by the common house fly, or certain other flies. 



CITY AND COUNTRY CONDITIONS COMPARED. 



While it is true that both malaria and typhoid prevail in large 

 cities, it is none the less true that they may with a certain degree of 

 accuracy be termed country diseases, that is to say, rather specific- 

 ally, diseases of the farm and the small village. Malaria, in fact, has 

 been called by medical men a country disease. Swampy regions do 

 not occur in cities, or, at all events, only in the suburbs, whereas they 

 occur commonly in the country. Open streams with side pools of 

 still water are found only in the country, and it is in such small, still 

 pools, and in more or less permanent but small accumulations of 

 water, that the malarial mosquito breeds. This mosquito, therefore, 

 does not accommodate itself well to city conditions, but it is found 

 almost everywhere in the country, except possibly in very dry locali- 

 ties and at certain high elevations. Even in dry regions it sometimes 

 abounds, especially where there is a definite rainy season, or where 

 the land is irrigated. Irrigating ditches are prolific breeding places 

 for mosquitoes, including the malarial kind. Malaria in cities, as a 

 rule, is found only with persons who have contracted it in the country 

 or in the suburbs, although with some cities having marshy places 

 on their borders a malarial belt may exist, the extent of which de- 

 pends upon the direction and force of the prevailing summer breezes, 

 especially the night breezes. For example, such a condition as this 

 accounts for the prevalence of malaria in certain portions of the city 

 of Washington before the reclamation of the Potomac Flats, which 

 lie to the south of the city, the prevailing night breezes of the sum- 

 mer being southern. 



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