MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 83 S 



Malaria 



Malaria is a disease caused by an amoeboid parasite of the red blood 

 corpuscles and is transmitted by the bite of anopheline mosquitoes 

 in which the parasite has completed the sexual cycle of its development. 



It exists in all parts of the tropical and subtropical world (Fig. 178). 



A young malarial parasite or sporozoit, derived from the mosquito enters a red cell 

 and supports itself by living upon the cell's substance. The parasite grows, proceeds 

 to multiply asexually and divides into a number of merozoites which are set free 



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07 



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SCHIZOCONV (Asexual GeneroHon) 

 in Man. 



® ©„ Q>..@ MerozoUei 



Macroffamete(^) ® © (i)Microffamete 



*•) W? 



^orozoUes. 



SPOROCONY (Sexual Generation) 



in die Mosquito 



Qwafatwith Sporohlasts. 



Oocifsl. 



^y Zyqote or 

 verm,ieule. 



Fig. 178. — Diagram illustrating the human and mosquito cycles of existence of 

 the malaria parasite. {After Martin's General Pathology.) 



by the rupture of the red cell. Those of the merozoites which escape ingestion by 

 the white cells of the blood enter red cells where they may again multiply asexually, or 

 they may develop into sexual forms. When blood, containing malarial parasites, is in- 

 gested by a suitable mosquito, all the parasites, except the adult sexual ones, are di- 

 gested and die. Soon after they are ingested, the macrogametocyte extrudes polar 



