Symposium on Exoerythrocytic Forms of Malarial Parasites. III. The Chemotherapy of Malaria in Relation to Our Knowledge of Exoerythrocytic Forms

Abstract

The literature dealing with the chemotherapeutic effects of all known compounds acting upon exoerythrocytic stages of avian, simian, and human malaria is reviewed and discussed. Causal prophylactic action was found in avian malarias by certain sulfonamides, naphthoquinones, biguanides, acridones, S-triazines, and a pyrimidine, and consequently these drugs may be presumed to exert a deleterious effect upon the pre-erythrocytic stages. A naphthoquinone (SN 8557) was the only drug found to be effective curatively in an established infection where exoerythrocytic stages were known to occur. Representative 8-aminoquinolines, with or without concomitant quinine, cured established sporozoite-induced cynomolgi infections in monkeys. The 8-aminoquinolines and biguanides were the only two groups of drugs showing possible activity against exoerythrocytic stages of human malaria. The 8-aminoquinolines exert both prophylactic and curative effects against Plasmodium falciparum and P. vivax. Paludrine is prophylactic against P. falciparum and partially prophylactic against P. vivax but is ineffective against an established vivax infection. A table giving the code numbers, the chemical names, empirical formulas and other designations of all drugs discussed for which there is direct or indirect evidence of activity against exoerythrocytic forms of malaria is included.