838 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



an insect-transmitted parasite, may be prevented by measures directed 

 either against the parasite or against the transmitting agent. 

 Malaria is caused by a Plasmodium and transmitted by the bites of 

 mosquitoes belonging to the Anophelinm. The disease may be com- 

 bated by destroying the parasite, in infected persons with quinine, and 

 by isolating such persons under mosquito nets so that mosquitoes may 

 never have an opportunity of ingesting the parasites which they harbor 

 in their blood. Malaria may also be prevented by destroying the 

 mosquitoes which transmit it. The most efficient way of ggtting rid 



Fig. 179. — ^Longitudinal section of Anopheles. A, head; B, thorax; C, abdomen 



I, oesophagus; 2, salivary glands; 3, dorsal reservoir; 4, ventral reservoir; 5, cana 

 entering stomach; 6, stomach; 7, malpighian tubes; 8, hind-gut; 9, rectum; 10, wings 



II, legs. (After Grassl, from Lang and Doflein.) 



of mosquitoes is to make it impossible for them to breed. The eggs 

 of a mosquito are laid in water, and water is absolutely necessary for 

 the larval and pupar stages, which must be passed through before the 

 adult mosquito is produced. Fish destroy developing mosquitoes and 

 large sheets of water are also too rough for them — so mosquitoes must 

 have, for breeding, rather small collections of fresh water free from 

 fish. Mosquitoes will soon disappear from a locality if all such col- 

 lections of water, within a quarter of a mile of it, are filled up, drained, 

 or covered with a film of coal oil so as to make it impossible for the 

 mosquitoes to breed in them. ' Those who live in a malarious district 

 should protect themselves from mosquito bites by the careful use of 

 mosquito-netting. By the simple observance of these evident indi- 

 cations, malaria has already been banished from several localities in 

 which it was formerly endemic. 



