The evaluation of the SumiOne™ spatial emanators against wild Anopheles funestus in experimental huts in Siaya County, western Kenya

Background Spatial Emanators (SEs) are a promising tool for complementing existing malaria vector control interventions. In 2025, the World Health Organization (WHO) issued a conditional recommendation for SEs, and two transfluthrin-based products were added to the WHO Prequalification List. As SEs are scaled up, additional products are needed to ensure reliable supply, competitive pricing, and continued innovation. Methods This study evaluated the efficacy of SumiOne SE, containing 10% metofluthrin, in experimental huts in Siaya County, western Kenya. SumiOne SE efficacy was evaluated in six experimental huts, three intervention and three control, using human landing catches (HLCs) and aspiration. Collections were conducted in two 12-night phases, alternating between HLC and aspiration every six nights. Outcomes included reductions in human landing rates, density, exophily and blood feeding inhibition of Anopheles mosquitoes. Results SumiOne SE significantly reduced indoor densities of An. funestus with 63% protective effect (IRR = 0.37, 95% CI: 0.20-0.69, p = 0.0087). Overall An. funestus density (indoor and outdoor combined) was reduced by 58% (IRR=0.42, 95% CI: 0.22-0.79; p=0.0222). The rate of exophily of An. funestus exiting was 34% (95% CI: 27-42) in the intervention huts compared to 2% (95% CI: 1-4) in the control huts (p< 0.0001). Blood feeding inhibition for An. funestus was 46% with 44% (95% CI: 36-51) of the collected mosquitoes being blood fed in the intervention huts compared to 81% (95% CI: 76-86) blood fed in the control huts, (p<0.0001). Conclusion These findings support SumiOne SEs potential as a complementary vector control tool, alongside existing core interventions such as Insecticide Treated Nets and Indoor Residual Spraying, particularly in contexts where additional protection is needed.