Primaquine prophylaxis against malaria in nonimmune Colombian soldiers: efficacy and toxicity. A randomized, double-blind, placebo-controlled trial

Abstract

Background: Primaquine had a prophylactic efficacy of 90% to 95% against infection with Plasmodium falciparum and P. vivax in Indonesian settlers.

Objective: To evaluate the efficacy of primaquine prophylaxis for protecting nonimmune persons from malaria.

Design: Randomized, double-blind, placebo-controlled field study.

Setting: A malaria-endemic area in Colombia.

Patients: 176 healthy, young, nonimmune adult male soldiers.

Intervention: Primaquine, 30 mg/d, or matching placebo during 15 weeks of patrol in the endemic area and 1 week afterward.

Measurements: Symptomatic parasitemia was determined over the 16-week intervention period and for 3 weeks in base camp.

Results: Protective efficacy in the primaquine group (122 participants) was 89% (95% CI, 75% to 96%) against all types of malaria, 94% (CI, 78% to 99%) against P. falciparum malaria, and 85% (CI, 57% to 95%) against P. vivax malaria. Six primaquine recipients had mild to moderate gastrointestinal distress, and three had severe distress.

Conclusions: For prophylaxis against P. falciparum malaria, primaquine has an efficacy and toxicity competitive with those of standard agents. A potential advantage of primaquine is that prophylaxis may be discontinued 1 week after the recipient has left the endemic area.