Can soap stop mosquitoes from biting? The answer is not so simple

It's called break-bone fever by some, and for good reason. Dengue Fever, for sure, is not something you want to catch. Perhaps worse again is Yellow Fever, which leaves an estimated 12% of sufferers with jaundice. Small percentages of those infected by either can develop severe hemorrhagic variants that can prove fatal.

Both fevers are caused by viruses carried by the aedes egypti mosquito. And while there is a Yellow Fever vaccine, which is required for entry into many African and Latin American countries, there is no widely used equivalent for Dengue.

But what if a thorough scrub with a well-known soap brand could put the mosquitoes off their lunch for long enough to prevent transmission?

It could be possible, going by experiments by a team from Virginia Tech, who had their findings published in the journal iScience in May.

Washing with some soaps attracts aedes aegypti mosquitoes, it seems, while other soaps drive the bloodthirsty flies away.

But that is only half the story. The effects of soap on the mosquitoes’ palates varied between different people and depended on "interactions between the soaps and each person’s unique odour profile."

A person can "be extremely attractive to mosquitoes" while unwashed, then can made more attractive to mosquitoes with one type of soap before repelling with another brand, the team found, after first categorising the chemical odours emitted by four human volunteers, first when unwashed and then after washing with four brands of soap — Dial, Dove, Native and Simple Truth.

"What really matters to the mosquito is not the most abundant chemical, but rather the specific associations and combinations of chemicals, not only from the soap, but also from our personal body odours," said senior author and neuroethologist Clément Vinauger, who suggested coconut-scented soaps could perhaps be the best all-round bet to keep mosquitoes at bay.

"Everybody smells different, even after the application of soap; your physiological status, the way you live, what you eat, and the places you go all affect the way you smell," said co-author and biologist Chloé Lahondère.