The value of house screening as an addition to long-lasting insecticidal nets in protecting against malaria in Zambia

Abstract

The aim of this study was to evaluate the impact of adding house screening to long-lasting insecticide-treated net (LLINs) use on malaria vector densities and malaria transmission potential in rural southeast Zambia.

The study was conducted in Nyimba district in four phases. First, baseline information on malaria vector species composition, relative abundance, sporozoite infectivity and entomological inoculation rates (EIRs) was collected. Second, the impact of combining house screening with LLINs on indoor mosquito densities and EIRs were evaluated in a randomized controlled trial. Intervention houses received LLINs plus house screening whilst the control arm households received LLINs only. Third, the durability of the window and door screens were assessed a year after screening. Fourth, community acceptability of the house screening intervention by the participants was assessed.

Anopheles rufipes, Anopheles funestus and Anopheles arabiensis were the main vectors in the study area. Closing eaves and screening doors and windows reduced indoor densities by an average 65%. EIR in unscreened houses was 2.91 infectious bites/person/six months (ib/p), higher than that in screened houses (1.88 ib/p/six months). After a year, window screens were intact. However, the wire mesh on most door screens was damaged on the bottom half. Participants accepted this intervention and linked house screening to reduced malaria in their households and cited sleeping peacefully due to reduced mosquito biting.

House screening has the potential to reduce malaria incidence, offer prevention against diseases, and provide additional benefits against nuisance biting and must therefore be promoted as a public health intervention.