G6PD and G6PD deficiency: Although the study population was limited to male participants who were G6PD-normal, previous studies have shown that a single low dose of primaquine (0·25 mg/kg) is safe in people with moderate severity G6PD deficiency (G6PD-Mahidol), and that a 3-day regimen of methylene blue was also safe in the generally less severe G6PD A-variant prevalent in Africa.6,7