There is growing evidence that the design of houses can reduce the strength of malaria infection.
The world’s deadliest killer is the malaria mosquito in Africa: Anopheles gambiae. In 2019, the World Health Organization estimated that malaria killed 386,000 people in sub-Saharan Africa, mostly children.
While we think of the home as a sanctuary, in Africa around 80% of malaria bites occur indoors at night. Preventing mosquitoes from getting indoors is an easy way to protect people from this often deadly disease.
While most mosquitoes fly low to the ground, a team of researchers led by Durham University wondered if, by raising a house, malaria mosquitoes would have a hard time finding occupants.
The results are published in the Royal Society Interface Journal.
Using four experimental houses, the researchers found that the number of female An. Gambiae collected from the huts decreased with increasing height, gradually decreasing as the hut floor moved away from the ground.
Huts with floors 3 meters above the ground sheltered 84% fewer mosquitoes than those on the ground. Interestingly, if this reduction correlates with a similar reduction in malaria transmission, it would be comparable to that of an insecticide-treated bed net which can reduce malaria transmission by 40-90%.
Lead author of the research, Professor Steve Lindsay, Department of Biosciences at Durham University, said: “Together with a team of architects and builders from the Royal Danish Academy – Architecture, Design and conservation, we built four experimental houses in The Gambia, each of them Each week one hut was on the ground, while the bottom of the other huts was 1m, 2m and 3m.
“Each night, two men slept under separate mosquito nets in each hut and the mosquitoes were collected inside using a light trap. We changed the height of each house each week so that at the end of the 40 night experience, each hut was at each of the four heights for 10 nights.
“After analyzing the results, we found that increasing the height of a hut gradually reduced the number of mosquitoes entering the hut and we believe there are two reasons for this.
“First, malaria mosquitoes evolved to find humans on the ground. Second, at higher heights, the plumes of carbon dioxide odor emerging from the huts are quickly blown away by the wind, making it harder for mosquitoes to find a person to bite.
Durham University PhD student Ms Majo Carrasco-Tenezaca said:
These findings have concrete implications for the growing population of sub-Saharan Africa where An. Gambiae sl is the main vector of malaria and places where high temperatures reduce net use.
Lifting houses off the ground, like any intervention, is not evolutionary evidence, and over time mosquitoes can adapt and feed higher than before.
Nonetheless, we recommend raising houses off the ground as they are likely to reduce mosquito bites and keep occupants cool at night, and therefore more likely to sleep under an insecticide-treated bed net at night. “
The United Nations has predicted that sub-Saharan Africa’s population will more than double between 2019 and 2050 and that the region will become the most populous in the world by 2062.
Along with the increased growth rate, there has been an unprecedented improvement in the housing stock in sub-Saharan Africa. With 1.05 billion more people by 2050, there’s never been a better time to make homes healthier for people.