PREVENTION OF MALARIAL FEVER 77 



mosquitoes becoming infected are much diminished. 

 Persons may be rendered insusceptible by the free use 

 of quinine, so that even if infected mosquitoes bite, the 

 parasites do not develop. This affords protection to 

 the individual, but either of these measures to be successful 

 requires practically universal dosing with quinine. 



II. Increased protection from mosquito bites by 

 mosquito nets, clothing better adapted for protection 

 against mosquitoes, mosquito-proof houses and the more 

 general and intelligent use of mosquito nets, are all 

 measures that may alone under exceptional circum- 

 stances prevent infection, and in any case are of great 

 value in diminishing the opportunities for infection 

 either of man or of the mosquito. 



III. Avoiding places where mosquitoes are probably 

 infected, in travelling by land, and sleeping in the 

 native huts or in the same clearing as the native village 

 should be avoided. It is safer to make the encampment 

 in the jungle, a mile or so from the native settlements. 

 Rest-houses and bungalows should not be built in or 

 near to a native settlement ; if they are in such situations 

 they should be avoided. 



Mosquitoes acquire the malarial parasite only from 

 man, and there is no reason to suppose that it can be 

 conveyed to the mosquitoes from any other source. 

 Experiments have been made, and it has been attempted 

 to infect the lower animals with human malaria, but 

 they have all failed. Anophelines may be present in a 

 place in large numbers, and yet there may be no malaria ; 

 if, however, they bite men already infected with malaria 

 they will spread the disease and that place will then 

 become very malarious. It is therefore important that 

 the human sources of infection should be known. In 

 this connection it is important to determine where men 

 get infected, and where the mosquitoes which infected 

 him become infected. The place where the infected 

 person spent the nights ten to fourteen days before he 

 got fever preferably twelve days before is the probable 



