PROPHYLAXIS IN YELLOW FEVER 257 



In preventing the spread of yellow fever, a knowledge 

 of their breeding-places is essential. In any country into 

 which yellow fever may be introduced the extermination 

 of these mosquitoes will render the spread of the disease 

 impossible ; and in all countries their extirpation will 

 greatly increase comfort. In a scattered settlement it 

 is an easy and inexpensive matter to render a house 

 free from this species of mosquito, but constant care is 

 required. The important point is that in such a place 

 the breeding-places are in the immediate surroundings 

 of the house. The occupier breeds his own mosquitoes. 

 In a more crowded settlement continued efforts are 

 required, and it should be made compulsory for each 

 occupier to free his own property from breeding-places ; 

 or the whole work may be done by the municipality at 

 the common expense. A combination of these methods 

 is most effective. It should be compulsory on the 

 occupier to free the actual premises from breeding- 

 places, and to have his water-tanks so protected that 

 mosquitoes cannot escape from them, and to see that 

 no accumulation of empty tins and bottles is present 

 in his compound. The municipality should remove 

 such bottles, and inspect and report on the condition 

 of drains, gutters, tanks, and stable surroundings as to 

 their freedom from larvae, and should make recom- 

 mendations to the occupier and enforce the carrying out 

 of such recommendations. The gutters must be well 

 graded and kept clean. The pipes supplying water to 

 the tanks must be long enough to reach the bottoms of 

 such tanks, otherwise the mosquitoes as they hatch out 

 will escape through this pipe. The manhole must be 

 kept covered, and it is better to have a double covering, 

 an inside one of gauze, and the ordinary solid one over 

 it. It is useless to attempt to render the supply pipe 

 impervious to mosquitoes by placing a gauze diaphragm 

 in any part of it, as the meshes soon become clogged 

 and the water will not pass through. An inspection and 

 collection of any portable breeding-places, e.g., bottles, &c ., 



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