CAUSE OF MALARIA 



483 



different types of malaria. This disease, not many years ago, was 

 thought to be caused by bad air. (Hence the name, from Italian 

 mala, bad ; aria, air.) But the work of a number of scientists 

 has shown that the disease is carried by a mosquito and is caused 

 by an amoeba-like organism, called Plasmodium malariae. When 

 a female mosquito of the 

 species Anopheles (a-nof 'e- 

 lez) sucks blood from a 

 person having malaria, 

 this parasite passes with 

 the blood into the stomach 

 of the mosquito. After 

 about twelve days in the 

 mosquito's body, the 

 parasites, having passed 

 through the sexual stages, 

 establish themselves 

 within the salivary glands 

 of the mosquito. If the 

 infected mosquito then 

 bites a person, it passes 

 the parasites into the 

 human blood with its 

 saliva. These parasites 

 enter the corpuscles of 

 the blood, increase in size, 

 and then form spores. 

 The rapid process of spore 

 formation results in the 

 breaking down of the blood corpuscles. The spores then escape 

 into the blood stream. The sudden release of the spores and the 

 poisons are thought to cause the chills and the fever so character- 

 istic of malaria. The escaped parasites may enter other blood 

 corpuscles and in forty-eight or more hours, depending on the kind 

 of malaria, repeat the cycle. The spores feed upon the red 

 corpuscles, and destroy half or even four fifths of the normal 

 number. This accounts for the pale, anaemic condition of a person 



The malarial parasite passes its life cycle from a 

 mosquito, to man, and back again to a mosquito. 

 Trace the life history of the parasite in the above 

 diagram. 



