HOW INSECTS AFFECT HEALTH TN RUEAL 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 b}' 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 specitically, 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 com- 

 monly 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 accom- 

 modate itself well to city conditions, but it is found almost everywhere 

 in the country, except possibly in very dry localities 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, includ- 

 ing 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 depends upon the direction 

 and force of the prevailing summer breezes, especially the night 

 breezes. For example, such a condition as this accounts for the prev- 

 alence 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 summer being southern. 



SOURCES OF TYPHOID FEVER. 



Cities well supplied with water from a reservoir, especially a filter 

 reservoir, which possess a modern sewage sj^stem, and in which 

 water-closets are universal, derive typhoid fever only from the follow- 



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