CHAPTER XXXIV 



MALARIA IN GENERAL 



By 



Robert Hegner 



The Johns Hopkins University School of Hygiene and 



Public Health 



INTRODUCTION 



Malaria is the most important disease of tropical and sub- 

 tropical countries. The parasites of malaria and the effects of the 

 parasite on the host have been studied intensively by large numbers 

 of well-trained zoologists, physicians and public health officers 

 ever since the causative organism was discovered by Laveran in 

 1880. Nevertheless there are many problems that still remain 

 unsolved and many results that need confirmation. Some of these 

 problems and methods for their study are presented in Chapters 

 XXXV to XXXIX inclusive. 



The malarial organisms are blood-inhabiting protozoa belonging 

 to the family plasmodid^. This family contains a single genus 

 Plasmodium. Three species occur in man, Plasmodium vivax, the 

 organism of tertian malaria, Plasmodium malaricB of quartan ma- 

 laria and Plasmodium falciparum of estivo-autumnal or malignant 

 tertian malaria. Malarial parasites have been described from 

 monkeys. They have been reported from the chimpanzee, gorilla, 

 orang-utan, baboon and over a dozen other species of Old World 

 and New World monkeys. At least eight distinct species have been 

 described from these animals but how many, if any, of these are 

 "good" species is still to be determined. Certain of these parasites 

 in monkeys rescmljle so closely the three species that occur in 

 man that they are morphologically indistinguishable. Reichenow 

 (1917, 1920) has described parasites in chimpanzees and gorillas 

 in the Cameroons that he believes to be the same as the human 

 species. Similar results were obtained by Blacklock and Adler 



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