Gametocytocidal and sporontocidal activity of some standard antimalarials on P. berghei (NK 65) infection M. natalensis.

Three standard antimalarials pyrimethamine, primaquine and quinine were tested against P. berghei (NK 65) for gametocytocidal and sporontocidal action. Pyrimethamine at 7.5, 3.25, 2.5 and 1.25 mg/kg., primaquine at 15, 10 and 7.5 mg/kg, quinine at 225, 168.5, 140.62 and 112.5 mg/kg were given orally to infected M. natalensis for 3 consecutive days i.e., day 6, 7 and 8 post inoculation of sporozoites. To assess sporontocidal action batches of mosquitoes (A. stephensi) were fed on infected-treated and control animals on day 8. Mosquitoes were dissected on day 10 post infective feed to compare the number of oocysts from control groups. Pyrimethamine at 2.5, primaquine at 10 and quinine at 140.62 mg/kg had total sporontocidal action. When mosquitoes were fed on animals treated with 2.5 mg/kg of pyrimethamine and 10 mg/kg of primaquine, very few oocysts were developed and sporozoites from these mosquitoes were not infective to Mastomys. When mosquitoes were fed on Mastomys treated with 140.62 mg/kg of quinine, no oocyst was observed.