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Efficacy of volatile pyrethroid spatial repellents to reduce exposure to mosquito and sand fly vectors and human infection risk: a systematic review and meta-analysis

N. Rawlings, M. Bailey, O. Courtenay

Parasites & Vectors, 2026

Abstract

Volatile pyrethroid spatial repellents (VPSRs) have emerged as promising complementary tools for vector control. This systematic review and meta-analysis evaluated the protective efficacy (PE) of VPSRs against mosquito- and sand-fly-borne human infections, and against vector numbers in traps. Clinical infection and entomological studies that evaluated VPSRs against human infection with Plasmodium, arboviruses (Dengue and Zika), and Leishmania, and against their respective vectors, were systematically reviewed. Random-effects meta-analyses estimated pooled PE values and explored moderators including vector trapping method, deployment setting (indoor/outdoor), and active ingredient (a.i.) concentration. A total of 49 VPSR studies containing 154 datasets met the inclusion criteria, comprising 6 trials (7 datasets) against human infection incidence, and 43 entomological studies mostly of mosquitoes (147 datasets); 73.5% tested active ingredients transfluthrin and 22.4% tested metofluthrin. Pooled estimates from transfluthrin VPSR trials indicated protective effects of 50% (95% CI 21–69%) against Plasmodium (n = 3) and 34% (95% CI 10–52%) against arboviruses (Dengue and Zika, n = 1). Evidence for Leishmania infection incidence was limited to a single trial (PE = 48%, 95% CI 26–63%). Metofluthrin showed no effect against Plasmodium (n = 1). Exposure to VPSRs was associated with substantial reductions in trapped mosquito and sand fly numbers. The comparative protection inferred…

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