Airflow may also be increased through other openings if the larger openings are closed enabling mosquitoes to more easily find these secondary entry points.Īn alternative system is to use semi-permeable barriers, such as mosquito netting, that allow air and light to enter the house but which prevent the mosquito from entering. This gap, in addition to allowing access to mosquitoes, provides illumination and ventilation and closing the opening with a solid barrier, as recommended by Kirby et al., may not be acceptable in many cases. Hence, mosquitoes, attracted to odour and carbon dioxide, tend to enter such houses via the gap between the roof and the walls. In many rural areas of Africa, houses are simple structures without windows. Reducing mosquito entry rates into houses is a simple way of reducing transmission and several methods to do this have been proposed, including building houses on stilts, using screens or blocking the gap between the roof and walls. Improvements to houses were important in reducing malaria transmission in the early part of the last century. Most malaria transmission occurs inside houses when people are asleep. gambiae s.l, by 84%, whilst untreated shade cloth reduced entry rates by 69% and entry rates were reduced by 76% in houses fitted with deltamethrin-impregnated shade cloth. Houses treated with mosquito netting reduced entry rates of An. funestus in houses treated with the deltamethrin-impregnated shade cloth compared to untreated houses. funestus in relation to untreated houses, but there was no difference in An. Houses treated with mosquito netting or the untreated shade cloth had 61.3% and 70% fewer An. Mosquito entry rates were assessed by light-trap collection and the efficacy of the different materials was determined in terms of incidence rate ratio (IRR), obtained through a Generalized Estimating Equations (GEE), of mosquito entry in a treated house compared to the untreated (control) house. Four experimental rounds (each of three weeks duration), from four houses randomly assigned to be a control or to receive one of the three intervention materials, were undertaken from March to August 2010 in the village of Furvela in southern Mozambique. MethodsĪ two-step intervention was implemented in which the gable ends of houses (the largest opening) were covered with one of three materials (four year old mosquito bed nets locally purchased untreated shade cloth or deltamethrin-impregnated shade cloth) followed by covering both gable ends and eaves with material. Therefore, a pilot study was conducted to investigate the protective effect of three types of material against Anopheles funestus and Anopheles gambiae s.l entry into village houses in Mozambique when applied over the large opening at the gables and both gables and eaves. More recently different materials that could also be used have come onto the market. Mosquito netting has previously been shown to have this effect. Reducing house entry rates in endophagic vectors by obstructing openings is one simple way of achieving this. One of the best ways to control the transmission of malaria is by breaking the vector-human link, either by reducing the effective population size of mosquitoes or avoiding infective bites.
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