Update: House modifications for preventing malaria
What is the aim of this review?
House modifications, such as screening (covering or closing potential house entry points for mosquitoes with mesh or other materials) or the use of specific house materials or designs, such as metals roofs instead of thatched roofs, or elevated rooms, may contribute to reducing the burden of malaria. They work by preventing mosquitoes from entering houses, and reducing the number of bites householders receive indoors. Some house modifications under consideration additionally aim to kill any mosquitoes that attempt to enter houses by incorporating insecticide into the modification.
Modifying houses to prevent mosquitoes entering the home was associated with a reduction in the proportion of people with malaria parasites in their blood and reduced anaemia, based on evidence from seven studies conducted in Africa. The effect of house modifications on the number of cases of malaria identified during specific time periods was mixed, and the effect on indoor mosquito density was less clear due to differences between study results. Six trials awaiting publication are likely to enrich the current evidence base.
What was studied in the review?
This review summarized studies investigating the effects of house modifications on human malaria outcomes. If studies additionally reported the effect of the house modifications on mosquitoes (those with potential to carry the parasites that cause malaria), or householders' views, we also summarized this data. After searching for relevant studies, we included seven published trials and six ongoing trials. All complete trials assessed screening (of windows, doors, eaves, ceilings, or any combination of these), either alone or in combination with roof modification or eave tube installation (a "lure and kill" device positioned in eave gaps to attract and kill mosquitoes). One trial incorporated insecticide into their house screening.
What are the main results of the review?
The seven included trials all assessed either the number of cases of malaria identified during specific time periods in people living in the house, the proportion of people with malaria parasites in their blood, or both. Overall, the studies showed that people living in modified houses were around 32% less likely to have malaria parasites in their blood, and were 30% less likely to experience moderate or severe anaemia. Our confidence in these results was moderate to high. The studies demonstrated 37% reduction in the number of mosquitoes trapped indoors at night in modified houses, although this result varied between trials. The trials showed mixed results for the likelihood of experiencing an episode of clinical malaria (caused by Plasmodium falciparum parasites), ranging from a 62% lower rate to a 68% higher rate of malaria for people living in modified houses. Due to the high inconsistency between these results, we have very low confidence in this evidence.
How up to date is this review?
The review authors searched for studies available up to 25 May 2022.