Indoor spatial repellents emanate a volatile active ingredient into a space, impacting a mosquito’s ability to successfully obtain a blood meal. Proportional reduction of mosquito bites is the most direct measure of protective efficacy (PE) of a spatial repellent, but reductions in human landing catches (HLC) and CDC light trap collections are commonly used alternatives. In this study, we compared the protective efficacy of Mosquito Shield™, a passive emanator spatial repellent, calculated using all three methods in an experimental hut trial in Lupiro, Tanzania. There was no significant difference between estimates of PE obtained through bite reduction (84%) or HLC (77%); however, PE measured through CDC light traps significantly underestimated impact of Mosquito Shield™ as compared to the other methods. Our research indicates that HLC can be used as an alternative to bite reduction for evaluating efficacy of spatial repellents, but that CDC light traps may significantly underestimate protective efficacy.
