Studies in Human Malaria

XXXII. The Protective and Therapeutic Effects of Pyrimethamine (Daraprim) Against Chesson Strain Vivax Malaria

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  • Laboratory of Tropical Diseases, National Microbiological Institute, National Institutes of Health, Bethesda 14, Maryland
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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.