London School of Hygiene & Tropical Medicine

A new method of preventing malaria transmission will be investigated in a collaborative project involving the London School of Hygiene & Tropical Medicine and led by Penn State University.

The new project will analyse an innovative method to limit mosquito access to houses, by blocking openings and installing 'eave tubes' that contain a unique type of insecticide-laced mosquito netting. The five-year study is funded by a $10.2 million (£7.1 million) grant from the Bill & Melinda Gates Foundation, of which $3.4 million (£2.3m) is awarded to the School to demonstrate the impact of eave tubes on malaria transmission within the first three years of the project.

Mosquitoes often enter houses through the eaves - the gaps between the roof and the walls. In the new approach these gaps are blocked and the eaves tubes are inserted to act like chimneys to funnel human odours to the exterior of the home. The mosquitoes are attracted to the human odours and enter the tubes, which contain netting treated with several kinds of powdered insecticides including biological agents. The eaves tubes were developed by Dutch project partner, In2Care.

An initial study by the team in southern Tanzania suggested that the eaves tubes reduced the presence of mosquitoes in houses by up to 90%.

Researchers will now conduct a randomised control trial  of strategy by installing eaves tubes in approximately 6,000 homes in villages in Côte d'Ivoire and Tanzania, to see if it can help reduce malaria in areas where mosquito populations are resistant to the widely-used pyrethroid insecticides.

Dr Raphael N'Guessan, Principal Investigator for the School who is working on the trial in Côte d'Ivoire, said: "We must continually search for ways to reduce malaria transmission, particularly as mosquitoes are becoming increasingly resistant to many common insecticides. This funding will allow our team of highly experienced entomologists, epidemiologists and socio-anthropologists in Cote d'Ivoire to investigate the 'eave tube' strategy and explore how we can use it most effectively against malaria in sub-Saharan Africa. I am delighted to be part of this exciting project."  

The trial will compare the households fitted with eaves tubes with homes in control villages that have not been fitted with the tubes, to determine the effect of the intervention on the number of cases of malaria. The team will also test the mosquitoes caught in the villages for insecticide resistance. Finally, they will conduct socio-economic analyses to find out how acceptable the technique is to homeowners, and create strategies for implementation across different regions and market sectors.

Matthew Thomas, Professor and Huck Scholar in Ecological Entomology who is leading the project for Penn State University, said: "The eave tube approach presents a novel strategy by simultaneously making houses more mosquito proof and providing a novel way of delivering insecticides, which creates opportunities for using a wider range of insecticidal products. The small amount of insecticide used in the tubes means that it is cheap to treat an entire house. Furthermore, retreatment is easy, as it requires simple replacement of small pieces of netting within the tubes."