Screened windows and stilts: test houses that cut mosquito visits by up to 95%

When public-health entomologist Steve Lindsay worked in Gambia in 1985, he met a villager nicknamed 'the professor' who blocked the gaps under his eaves and built his evening resting platform two meters high. His reasoning was pure field ecology: fewer openings, fewer mosquitoes; higher perch, fewer bites. That folk engineering became a research program, because the standard tool — insecticide-treated bed nets — traps heat, and many people simply stop using them.

Starting in 2017 near Welingara village, Lindsay's team built experimental huts with deliberately badly fitting doors — the common entry point in rural homes — and volunteers sleeping two per house while light traps counted mosquitoes. Changing one variable at a time, they found screened windows cut mosquito visits precipitously: huts with three large screened windows caught 95% fewer than huts with solid metal 'windows.' Airflow modeling showed ventilation breaks up the stagnant CO2 clouds that attract mosquitoes; indoor CO2 fell up to 36%, and screened huts ran about 1 degree cooler.

In 2019 the team tested elevation with wood-and-tin homes that could be cranked up on stilts by a pulley: one meter above ground drew 40% fewer mosquitoes, two meters 68% fewer, three meters 84% fewer. The results were published in the Journal of the Royal Society Interface in May 2021. With team member Jakob Knudsen, a Danish architect, Lindsay launched the Star Homes Project in Tanzania — a three-year clinical trial tracking malaria among children in 110 two-story homes with breathable shade-cloth walls across 60 villages, compared with 440 traditional homes.

Don't seal the house — vent it. Screened windows flush out the CO2 that guides mosquitoes in; raising the home lifts sleepers out of their flight band.

Exhaled CO2 is the mosquito's beacon, so venting it turns the house into what Lindsay calls a stealth house that hides its occupants.

Screening cut mosquito entry directly while keeping the house cooler — and comfort is what makes protection stick where hot nets go unused.

Raising the home exploits the insects' low hunting band, a lever no bed net or spray touches.

Expert observers like Fredros Okumu of the Ifakara Health Institute argue malaria is primarily a problem of poor housing and surface water, so design is a sustainable control.

The fix for a biology problem can be architectural: change the cues and the geometry instead of adding another chemical to the fight.

Turning trials into housing is the hard part: Patrick Kelley of Habitat for Humanity's Terwilliger Center notes few people change their homes because of academic papers, and points to building codes or, more optimistically, consumer behavior — putting screening knowledge into the markets where people buy wood. Lindsay bets on the architect's route: build something people want to copy. The Star Homes trial, with its 110 test homes across 60 villages, is the large-scale test of whether the design actually cuts malaria.