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

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.