Impact and cost-effectiveness of a lethal house lure against malaria transmission in central Côte d'Ivoire: a two-arm, cluster-randomised controlled trial

Eleanore D Sternberg,Jackie Cook,Ludovic P Ahoua Alou,Serge Brice Assi,Alphonsine A Koffi,Dimi T Doudou,Carine J Aoura,Rosine Z Wolie,Welbeck A Oumbouke,Eve Worrall,Immo Kleinschmidt,Raphael N'Guessan,Matthew B Thomas

doi:10.1016/s0140-6736(21)00250-6

Abstract

SummaryBackgroundNew vector control tools are required to sustain the fight against malaria. Lethal house lures, which target mosquitoes as they attempt to enter houses to blood feed, are one approach. Here we evaluated lethal house lures consisting of In2Care (Wageningen, Netherlands) Eave Tubes, which provide point-source insecticide treatments against host-seeking mosquitoes, in combination with house screening, which aims to reduce mosquito entry.MethodsWe did a two-arm, cluster-randomised controlled trial with 40 village-level clusters in central Côte d'Ivoire between Sept 26, 2016, and April 10, 2019. All households received new insecticide-treated nets at universal coverage (one bednet per two people). Suitable households within the clusters assigned to the treatment group were offered screening plus Eave Tubes, with Eave Tubes treated using a 10% wettable powder formulation of the pyrethroid β-cyfluthrin. Because of the nature of the intervention, treatment could not be masked for households and field teams, but all analyses were blinded. The primary endpoint was clinical malaria incidence recorded by active case detection over 2 years in cohorts of children aged 6 months to 10 years. This trial is registered with ISRCTN, ISRCTN18145556.Findings3022 houses received screening plus Eave Tubes, with an average coverage of 70% across the intervention clusters. 1300 eligible children were recruited for active case detection in the control group and 1260 in the intervention group. During the 2-year follow-up period, malaria case incidence was 2·29 per child-year (95% CI 1·97–2·61) in the control group and 1·43 per child-year (1·21–1·65) in the intervention group (hazard ratio 0·62, 95% CI 0·51–0·76; p<0·0001). Cost-effectiveness simulations suggested that screening plus Eave Tubes has a 74·0% chance of representing a cost-effective intervention, compared with existing healthcare activities in Côte d'Ivoire, and is similarly cost-effective to other core vector control interventions across sub-Saharan Africa. No serious adverse events associated with the intervention were reported during follow-up.InterpretationScreening plus Eave Tubes can provide protection against malaria in addition to the effects of insecticide-treated nets, offering potential for a new, cost-effective strategy to supplement existing vector control tools. Additional trials are needed to confirm these initial results and further optimise Eave Tubes and the lethal house lure concept to facilitate adoption.FundingThe Bill & Melinda Gates Foundation.

Highlights

Widescale implementation of core vector control— long-lasting insecticidal nets and indoor residual spraying—has contributed to substantial reductions in the burden of malaria.[1,2] these reductions have plateaued[2], and new control strategies are needed to attain the milestones laid out in the WHO Global Technical Strategy for malaria control.[3,4,5]One growing area of interest is the potential role of housing improvements.[6,7] Many traditional house designs in Africa have open eaves
The In2Care (Wageningen, Netherlands) Eave Tube is one such approach, consisting of ventilation tubes made from pieces of polyvinyl chloride (PVC) pipe embedded in a closed eave.[17]
Percentage of children living in houses of suitable structure for screening plus Eave Tubes

Summary

Introduction

Widescale implementation of core vector control— long-lasting insecticidal nets and indoor residual spraying—has contributed to substantial reductions in the burden of malaria.[1,2] these reductions have plateaued[2] (probably due to numerous causes, including insecticide resistance, poor availability or misuse of bednets, urbanisation, and limits on donor funding), and new control strategies are needed to attain the milestones laid out in the WHO Global Technical Strategy for malaria control.[3,4,5]. One growing area of interest is the potential role of housing improvements.[6,7] Many traditional house designs in Africa have open eaves (the area where the wall joins the roof of a house). Mosquitoes are drawn into the Eave Tubes, which funnel the heat and Lancet 2021; 397: 805–15

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