In2Care part of $10.2 million study to test new malaria-prevention method

Photo above: Tanzanian house fitted with eave tubes

“In 2015 an estimated 438 thousand mostly African children and pregnant women died of malaria,” said In2Care’s Director Bart Knols. “Although we have achieved tremendous progress over the last fifteen years and have saved countless lives by using insecticide-treated bednets and indoor spraying with insecticides, resistance to insecticides in mosquitoes is spreading rapidly which may undermine these fragile gains. Eave tubes combine two approaches: First the house is rendered mosquito-proof and second the tubes represent a novel approach to target mosquitoes as they try to enter the house in search of a blood meal.The beauty of it all is that houseoccupants don’t need to do anything, it is passive technology.”

According to Matthew Thomas, who will head the study at Penn State, African malaria mosquitoes have a strong preference for entering houses at night through eaves — the gaps between the roofs and the walls of houses. The team’s novel eave tube approach involves blocking the eaves and inserting tubes that act like chimneys to funnel human odors to the exterior of the home. Attracted to the human odors, mosquitoes enter the tubes and encounter netting that has been treated with an electrostatic coating that binds insecticidal particles to it. The netting can hold several kinds of powdered insecticides, including biological agents, and has been shown to break resistance with currently recommended insecticides.

“Since insecticide is only used on small pieces of netting in the tubes, the reduction compared to spraying walls of entire houses is massive, making eave tubes highly cost competitive, especially now that more expensive insecticides are needed due to resistance against the cheaper ones” said Knols. “Furthermore, retreatment is easy, as it requires simple replacement of small pieces of netting within the tubes.”

With a $ 5.6 million grant from the EU, the collaborative team of researchers has already conducted a proof-of-concept intervention in which they installed eave tubes in more than 1,800 houses in the Kilombero valley in southern Tanzania. The team found that the eave tubes reduced indoor mosquito densities by up to 90 percent.

The new project funded by the Gates Foundation expands on the previous intervention by installing eave tubes in approximately 6,000 homes in villages in Cote d’Ivoire and Tanzania. The researchers will examine householders in these villages and compare them with equivalent control villages that have not been supplied with eave tubes to determine the effect of the intervention on malaria incidence. The team also will test the mosquitoes caught in the villages for insecticide resistance. Finally, the researchers will conduct socio-economic analyses to determine homeowner acceptance and create strategies for implementation across different regions and market sectors.

“We know that eave tubes can perfectly kill mosquitoes when they contact electrostatic netting; even the ones resistant to insecticides. But that’s not enough to convince policy makers that this approach can be added to the arsenal we have at present. Quite rightly so, before a new approach can be adopted we need to clearly measure the overall impact on disease, not just mosquitoes. That’s what we aim to do in this unique project,” Knols said. “If we are to eradicate malaria from the face of the planet over the next decades it will be essential to move new strategies forward, and especially those that can help to break the vicious circle of insecticide resistance. This is what eave tubes offer.”