The tiny mosquito-borne parasites that cause malaria may also change the body odour of those they infect, making people more attractive to mosquitoes that spread it.
It is well-known that some people seem to attract more mosquito bites than others. Past research has suggested that the chemicals found in body odour – which may be influenced by your genes or hormones – play a role in how attractive you are. at the London School of Hygiene and Tropical Medicine and her colleagues sought to find out which chemicals might be to blame.
The team collected socks worn by Kenyan children, some of whom were infected with the parasite that causes malaria. In a test, they found that mosquitoes seemed to be more attracted to the socks worn by children with the parasite. When they later ran the experiment again, the mosquitoes were less attracted to these children’s socks once they had been treated for malaria, and no longer carried the parasite.
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This suggests that people with malaria are particularly attractive to mosquitoes. It’s possible that the malaria parasite has evolved a way to make us change our body odour, to attract more mosquitoes and help spread the parasite to others.
Rotten smell
The team isolated individual compounds from the socks, to see which were most attractive to mosquitoes. The mosquitoes’ antennae – which they use to sense odour – became more active when they were exposed to nonanal and a few other generally harmless compounds. “Nonanal has a rotten smell, and is what you smell when fatty food is going off,” says of Cardiff University, who collaborated on the project.
The team don’t yet know how the parasite might trigger any change in body odour chemistry. The body’s immune response to the parasite may be involved, suggests Pickett.
It is likely that the compounds interact with each other, and other components of human skin, to create complex brews of chemicals that attract insects, says Pickett. He hopes to eventually develop scents that repel mosquitoes from people and others that attract them to traps. “You’d protect the person and also reduce the pest,” he says.
PNAS
Read more: Malaria parasite makes mosquitoes more likely to suck your blood
