MALARIA 



279 



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

 by an amoeba-like organism, called plasmo'dium. When a female 

 mosquito of the species anopheles (a-nof'e-lez) sucks blood 

 from a person having malaria, this parasite (P in diagram) passes 

 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 (A in dia- 

 gram) 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 and the release of 

 the spores, with the poisons 

 they manufacture, into the 

 blood. This causes the chill 

 followed by the fever so 

 characteristic of malaria. 

 The spores (H in diagram) 

 may again enter the blood 

 corpuscles and in forty- 

 eight or seventy-two hours, 

 depending on the kind of 

 malaria, repeat the process thus described. The spores feed upon 

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

 normal number. This accounts for the pale, anemic condition of- 

 a person who has malaria. The only cure for the disease is qui- 

 nine in doses of from 5 to 10 grains per day. This kills the para- 

 sites in the blood. 



The Malarial Mosquito. — Fortunately for mankind, not all 

 mosquitoes harbor the parasite which causes malaria. The harm- 

 less mosquito (culex) may be usually distinguished from the mos- 

 quito which carries malaria (anopheles) by the position of the body 





-^^p 



Life history of the malarial parasite. Follow 

 the course shown by the arrows from A back to 

 A and compare with text, also from H back 

 toH. 



