Insecticide treated eave nets and window screens for malaria control

点击翻译按钮获取中文摘要

Long lasting insecticidal nets (LLIN) are a key component of malaria control and are responsible for saving many lives; but they have several drawbacks. About half of people living in malaria endemic areas do not have access to LLINs. Some of this deficit is due to insufficient delivery of nets, but a major factor is LLINS becoming rapidly damaged, resulting in a lifespan less than their intended 3-years. Additionally, there is typically an unequal distribution of nets to certain groups within households. For example, while the youngest children and their mothers are likely to sleep under nets, school age children often have very low access to nets. And even those who do have access to nets are only protected when they are sleeping. We propose a new tool - purpose made insecticide-treated eave nets (ITENs) with insecticide treated window screens (ITWS) for full house screening. ITENs are purpose made netting rolls that are applied to the house under the overhang of the roof and across windows within 30 minutes by local teams using hammer and nails. These interventions have at least three potential advantages over LLINs: they protect everybody in the household; they protect them at all times when they are in the household; and the are potentially much more durable than LLINs, giving up to 5 years' protection and making them highly cost effective (up to $1.75 per year per household less than LLINs). ITENs fixed across the eaves of household structures and ITWS on the windows block access to and kill Anopheles mosquitoes at their main access points into houses. Mosquitoes are attracted to houses, try to enter through the eaves or windows, and will come up against insecticides in the interventions, turning the house into a "lure and kill", that not only protect people in the house but also everyone in the community. Preliminary household randomised evaluation of ITENs and ITWS among 80 households in Western Kenya in 2012-14 showed 75% fewer vector mosquitoes in the houses using ITENs, ITWS and LLINs when compared to households using LLINs only. ITENs and ITWS are already available and scalable and can be fitted to any type of house.ITENs and ITWS have advantages over LLINs for the application of insecticides. LLINS are touched daily and washed regularly, limiting the range of chemicals which can be applied. ITENs and ITWS are compatible with a wider range of insecticides. This will be greatly advantageous because insecticides used for malaria control are becoming less effective in Africa due to the growing resistance of mosquitoes - and particularly because resistance is a local phenomenon: chemicals that work in one place may be ineffective in another so it is vital to have a wide choice of insecticides. In addition, ITENs and ITWS can be made from denser, more durable material. This not only makes them more physically durable but allows a greater quantity of insecticide to be impregnated, killing more mosquitoes, even resistant ones, and making the effect last longer. We propose in due course to undertake a large-scale cluster randomised trial with epidemiological endpoints in Tanzania. However, before this is possible it is necessary to investigate which particular combination of insecticides, is appropriate to the local conditions. We also wish to undertake a study to assess how feasible it is to fit ITENs and ITWS to local houses and how acceptable local communities find them. We are therefore applying for a development grant for a 2 small preliminary studies: one in experimental huts, which will be conducted to compare the household and community protective efficacy of 2 ITEN and ITWS products with different insecticides in local conditions to see which is better to take forward to a large scale trial; and a second in which 200 local houses are fitted with ITENs and ITWS and followed up after 1 year to assess ease and cost of fitting, longevity and community acceptability.