Abstract
BackgroundDespite considerable reductions in malaria achieved by scaling-up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), maintaining sustained community protection remains operationally challenging. Increasing insecticide resistance also threatens to jeopardize the future of both strategies. Non-pyrethroid insecticidetreated wall lining (ITWL) may represent an alternate or complementary control method and a potential tool to manage insecticide resistance. To date no study has demonstrated whether ITWL can reduce malaria transmission nor provide additional protection beyond the current best practice of universal coverage (UC) of LLINs and prompt case management.Methods/designA two-arm cluster randomized controlled trial will be conducted in rural Tanzania to assess whether non-pyrethroid ITWL and UC of LLINs provide added protection against malaria infection in children, compared to UC of LLINs alone. Stratified randomization based on malaria prevalence will be used to select 22 village clusters per arm. All 44 clusters will receive LLINs and half will also have ITWL installed on interior house walls. Study children, aged 6 months to 11 years old, will be enrolled from each cluster and followed monthly to estimate cumulative incidence of malaria parasitaemia (primary endpoint), time to first malaria episode and prevalence of anaemia before and after intervention. Entomological inoculation rate will be estimated using indoor CDC light traps and outdoor tent traps followed by detection of Anopheles gambiae species, sporozoite infection, insecticide resistance and blood meal source. ITWL bioefficacy and durability will be monitored using WHO cone bioassays and household surveys, respectively. Social and cultural factors influencing community and household ITWL acceptability will be explored through focus-group discussions and in-depth interviews. Cost-effectiveness, compared between study arms, will be estimated per malaria case averted.DiscussionThis protocol describes the large-scale evaluation of a novel vector control product, designed to overcome some of the known limitations of existing methods. If ITWL is proven to be effective and durable under field conditions, it may warrant consideration for programmatic implementation, particularly in areas with long transmission seasons and where pyrethroid-resistant vectors predominate. Trial findings will provide crucial information for policy makers in Tanzania and other malaria-endemic countries to guide resource allocations for future control efforts.Trial registrationNCT02533336 registered on 13 July 2014.
Highlights
Despite considerable reductions in malaria achieved by scaling-up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), maintaining sustained community protection remains operationally challenging
Primary objective To assess the effectiveness of Insecticidetreated wall lining (ITWL) + LLINs compared to LLINs alone, on cumulative incidence of malaria parasitaemia in children aged 6 months to 11 years old
Malaria infection will be detected by malaria rapid diagnostic test (mRDT; One Step Malaria HRP-II (P.f ) and pLDH (Pan) Antigen Rapid Test, Standard Diagnostics Inc., Korea) and positive children will be treated according to national guidelines
Summary
The future of malaria control in Sub-Saharan Africa is threatened by problems of consistent use, sustainability and the rapid expansion of pyrethroid-resistant vector populations. While reductions in disease burden achieved by LLINs and IRS are irrefutable, the development of novel vector control strategies and insecticide delivery mechanisms will be crucial to maintain gains and facilitate the movement towards malaria elimination and eradication This is the largest cluster randomized controlled trial to evaluate whether non-pyrethroid ITWL can provide additional protection against clinical malaria compared to the current best practice of UC with LLINs. The potential longer lifespan and residual activity of ITWL, the absence of repeated intervention costs, and community-wide effect may render ITWL a superior control technique to LLINs alone. The operational success of ITWL will be determined by its demonstrable protective efficacy and its feasibility of implementation, levels of household acceptability, durability under field conditions and costeffectiveness compared to other first-line strategies This trial will investigate the effectiveness of ITWL in a ‘realto-life’ community setting and aims to establish a precedent in multidisciplinary evaluations of new large-scale control interventions.
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