Abstract
Background
Blocking the transmission of parasites from humans to mosquitoes is a key component of malaria control. Tafenoquine exhibits activity against all stages of the malaria parasite and may have utility as a transmission blocking agent. We aimed to characterize the transmission blocking activity of low dose tafenoquine.
Methods
Healthy adults were inoculated with
P. falciparum 3D7-infected erythrocytes on day 0. Piperaquine was administered on days 9 and 11 to clear asexual parasitemia while allowing gametocyte development. A single 50 mg oral dose of tafenoquine was administered on day 25. Transmission was determined by enriched membrane feeding assays pre-dose and at 1, 4 and 7 days post-dose. Artemether-lumefantrine was administered following the final assay. Outcomes were the reduction in mosquito infection and gametocytemia post-tafenoquine, and safety parameters.
Results
Six participants were enrolled, and all were infective to mosquitoes pre-tafenoquine, with a median 86% (range: 22–98) of mosquitoes positive for oocysts and 57% (range: 4–92) positive for sporozoites. By day 4 post-tafenoquine, the oocyst and sporozoite positivity rate had reduced by a median 35% (IQR: 16–46) and 52% (IQR: 40–62), respectively, and by day 7, 81% (IQR 36–92) and 77% (IQR 52–98), respectively. The decline in gametocyte density post-tafenoquine was not significant. No significant participant safety concerns were identified.
Conclusion
Low dose tafenoquine (50 mg) reduces
P. falciparum transmission to mosquitoes, with a delay in effect.
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