512 Malaria 



Bass and Johns believe that quinin has no direct effect upon the 

 malarial parasites, but effects its curative influence by rendering the 

 substance of the •corpuscles more permeable to the all-suflicient de- 

 structive influence of the serum. The quinin would then affect only 

 the parasites in the circulation, and not those lodged in the capil- 

 laries, which would not be reached until they had segmented. The 

 effect of quinin is* said to be defeated by influences such as diet, 

 exertion, etc., which increase the dextrose content of the blood, 

 whereby the permeability of the red blood-cells seems to be de- 

 creased. It is hoped that a better understanding of the principles 

 involved in the treatment of malaria may result from the study of 

 the organism in culture by which empiricism may be exchanged for 

 rationalism. 



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 t3^e 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 sple'en 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 tis- 

 sue is pigmented. The liver and kidneys are also enlarged and 

 pigmented. 



Prophylaxis. — With the knowledge of the r61e of the mosquito 



