Indoor Residual Spraying in Combination with Insecticide-Treated Nets Compared to Insecticide-Treated Nets Alone for Protection against Malaria: A Cluster Randomised Trial in Tanzania

Indoor Residual Spraying in Combination with Insecticide-Treated Nets Compared to Insecticide-Treated Nets Alone for Protection against Malaria: A Cluster Randomised Trial in Tanzania

Objectives

The aim of this research is to determine whether it is necessary to maintain IRS once malaria transmission has been reduced or whether following the scaling-up of LLINs the IRS can be withdrawn and low transmission rates can be maintained equally well with LLINs alone.

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Principal Investigator (PI)

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Abstract

Vector control, together with prompt treatment with an artemisinin-based combination therapy (ACT) for individuals diagnosed with malaria and intermittent preventive treatment in pregnant women, is a critical component of malaria control in Africa. The two main vector control interventions used in Africa are long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). LLINs are currently the mainstay of vector control and are believed to have contributed to the recent dramatic decline in malaria cases. However, resistance to the pyrethroid insecticides used in the bed nets has increased. The second main vector control method, IRS, has been an extremely effective adjunct to LLINs; its usefulness is threatened by the high cost of repeated applications and increasing mosquito resistance to insecticides used for spraying.

A new product, durable lining (DL) treated with non-pyrethroid insecticides, has been developed by Vestergaard, which theoretically mimics the effect of IRS but is designed to last for a minimum of three years. The product consists of a mixture of two non-pyrethroid insecticides incorporated into a polymer fabric that are designed to migrate differentially over the lifetime of the product to ensure sustained bioefficacy. The use of two agents may also decrease the risk of development of resistance. It is estimated that the cost of the insecticide treated wall liners (DL), which are installed on the indoor walls of houses, would be equal to 2-3 rounds of IRS.

To test the effectiveness of this new product, we will conduct a two-arm controlled randomized cluster trial to test the hypothesis that DL + LLINs are superior to LLINs alone. Over twelve (12) months (August 2015- Aug 2016), in an area with universal coverage (UC) of LLINs and where artemisinin combination therapies (ACT) are provided as the first-line treatment of malaria, we intend to evaluate the impact of DL on malaria transmission among children ages 6 months to 11 years as measured by the incidence of malaria parasitemia (symptomatic and asymptomatic), and the prevalence of moderate to severe anemia in under-fives. In addition, we will assess the effect of DL on entomological parameters, and measure the acceptability and a cost-effectiveness of the intervention. Stratified randomization based on malaria prevalence during the baseline survey will be used to select 22 clusters per arm in Muheza district.

The Effectiveness of Non-Pyrethroid Insecticide-Treated Durable Wall Liners as a Method for Malaria Control in Endemic Rural Tan

Key facts

  • Dates
    Jul 2013 to Aug 2016
    Funding amount
    $1,600,000
    Country
    • Tanzania, United Republic of

MESA tags

  • Methodology
    Entomology, Operational research
    Theme(s)
    Impact of interventions, Insecticide resistance, Tools for elimination