Studies in Human Malaria

Abstract

Summary This study was undertaken to evaluate the protective and therapeutic efficacy of pyrimethamine (Daraprim) against Chesson strain Plasmodium vivax in human volunteers. The drug was highly effective as a suppressive agent, 0.8 to 25 mg. gave complete protection during drug administration; it was less efficient when used for therapy of acute attacks. Pyrimethamine does not appear to be a true causal prophylactic although prolonged delays before patent parasitemia suggested some deleterious effect against early tissue stages of the parasite. Weekly administration of the drug for 8 or more weeks resulted in suppressive cure of many infections. Probably the greatest usefulness of the drug will be for routine suppression.