486 Malaria 



Animal Inoculation. -The human malarial parasites cannot be 

 successfully transmitted by experimental inoculation to any of the 

 lower animals. 



Human Inoculation. The blood of one human being contain- 

 ing schizonts, when experimentally introduced into another human 

 being in doses of i to 1.5 cc. transmits the disease. When thus 

 transmitted, an incubation period of from seven to fourteen days 

 intervenes before the disease, which is of the same type as that from 

 which the blood was taken, makes its appearance. 



Pathogenesis. The pathogenic effects wrought by the malarial 

 parasite are imperfectly understood. The synchrony of the seg- 

 mentation of the parasite with the occurrence of the paroxysms 

 seems to indicate that a toxic substance saturates and disturbs the 

 economy at that time. Whether it be an endotoxin liberated by 

 the dividing parasite is not, however, known. 



The anemia that follows infection can be referred to the destruc- 

 tion of the red blood-corpuscles by the parasites which feed upon 

 them and transform the hemoglobin into melanin (?). When 

 great numbers of the parasites are present the destruction is enor- 

 mous, and the number of corpuscles and the quantity of hemoglobin 

 in the blood sink far below the normal. Leukopenia instead of 

 leukocytosis is the rule, and while the leukocytes have an appetite 

 for the spores of the parasites and often phagocyte and destroy them, 

 their activity is not sufficiently rapid or universal to check their 

 rapid increase. 



The melanin granules set free during sporulation are also taken 

 up by the leukocytes and endothelial cells, the latter becoming 

 deeply pigmented at times. 



The spleen enlarges as the disease continues until it forms the 

 " ague-cake." The enlargement may cause the organ to weigh 7 

 to 10 pounds. It appears to result from hypertrophy. The tissue 

 is pigmented. The liver and kidneys are also enlarged and 

 pigmented. 



Prophylaxis. With the knowledge of the role of the mosquito 

 in the transmission of malaria, its prophylaxis becomes a matter 

 of simplicity when certain measures can be systematically carried 

 out. There are two equally important factors to be considered 

 the human being and the mosquito. The measures must be di- 

 rected toward preventing each from infecting the other. 



i. The Human Beings. In districts where malarial fever pre- 

 vails, the first part of the campaign had perhaps best be directed 

 toward finding and treating all cases of malarial fever, so that the 

 parasites in their blood may be destroyed and the infection of 

 mosquitoes prevented. This is done by the systematic and general 

 use of quinin. 



All cases of malarial fever should be required to sleep in mosquito- 

 proof houses under nets, and as the mosquitoes are nocturnal and 



