Effect of Antimalarial Treatment on Gametocyte Carriage in Asymptomatic P. Falciparum

Treatment of P. falciparum malaria with sulfadoxine-pyrimethamine (SP) is followed by a sharp rise in the density of gametocytes. Drug-induced release could enhance transmission of resistant parasites and would argue against the use of SP, especially for intermittent preventive treatment (IPT). We did a randomized trial to determine the effect of treatment with SP on gametocyte carriage. The trial is a three-arm open-label randomized trial. We randomized asymptomatic carriers of P.falciparum to receive antimalarial treatment or placebo, and recorded the prevalence and density of gametocytes over the next 2 months. The trial was conducted during the dry (low malaria transmission) season in four rural villages in The Gambia. Adults and children aged over 6 months who had asexual P.falciparum infection and were confirmed to be free of clinical symptoms of malaria over a 2-day screening period were enrolled and randomized to receive a single dose of SP, or SP plus a single dose of artesunate (SP+AS), or placebo. The primary endpoints were presence of gametocytes 7 and 56 days after treatment, and the duration and density of gametocytaemia over 2 months measured by the area under the curve of gametocyte density against time.

Inclusion criteria

• P.falciparum parasitaemia above 20/uL
• Resident in one of the four study villages

Exclusion criteria

• Fever
• Any other sign of clinical malaria
• Pregnancy
• Weight <5kg
• History of hypersensitivity to any of the study drugs
• Treatment with any of the study drugs in the last 4 weeks