(Photo: Sylvain Thomas/AFP)
Have you ever felt like mosquitoes are constantly biting you while other people next to you remain seemingly unaffected? Scientists are now making progress in unraveling the complex chemical composition that makes certain people particularly attractive to these leeches.
“This is not a misconception – mosquitoes are indeed attracted to some people more than others,” Frédéric Simard of France’s Institute for Research and Development told AFP.
He says that humans are not always equally attractive to mosquitoes.
Several sensory signals influence how mosquitoes choose their victims. The most important are body odor, body heat and the carbon dioxide that people exhale.
Only female mosquitoes bite humans. They use highly specialized receptors to detect these signals before choosing a target.
According to the Swedish scientist Rickard Ignell, researchers have known for more than a century that mosquitoes are attracted by carbon dioxide.
“This is the first signal that activates their behavior when they are still tens of meters away,” he said.
When mosquitoes come within about ten meters of a person, they also begin to perceive body odors. The combination of smell and carbon dioxide makes people even more attractive. Closer-up, body heat and humidity also play an important role.
(Photo: iStock)
Blood group doesn’t matter
However, several popular theories about mosquitoes are not scientifically confirmed.
According to Simard, the idea that mosquitoes prefer certain blood types has no strong scientific basis.
“There have been studies, but they have only included very small groups of people,” he said.
He adds that there is also no proven connection with skin, eye or hair colour.
However, body odor plays a big role.
According to Simard, the human microbiota – the micro-organisms that live on the skin – produce a unique mix of molecules that mosquitoes find more or less attractive.
Research shows that humans secrete between 300 and 1,000 different odor compounds, but scientists are only now beginning to understand which ones attract mosquitoes the most.
In a recent study, Ignell and his team recruited 42 women Aedes aegypti-mosquitoes, which spread yellow fever among other things, exposed to determine who the mosquitoes prefer.
The researchers identified 27 specific odor compounds that mosquitoes can detect.
The women who were bitten the most – among them pregnant women in their second trimester – secreted large amounts of a particular compound that is created when the skin oil breaks down sebum.
“It’s amazing how sensitive mosquitoes are to this,” Ignell said.
Aedes mosquitoes are studied Photo: Felipe Dana/Associated Press
Beer makes you smell more attractive
Several studies have also found that beer makes people more attractive to mosquitoes.
It raises body temperature, changes skin odors and causes people to exhale more carbon dioxide.
In a study in Burkina Faso, volunteers drank beer on one occasion and water on another, after which researchers compared the response of mosquitoes.
Die Anopheles-mosquito, which can spread malaria, was clearly more attracted by the beer drinkers.
A 2023 Dutch study involving 465 volunteers found that people who drank beer within the previous 24 hours were 1.35 times more attractive to mosquitoes.
Climate change increases risk
The question of why mosquitoes prefer certain people is becoming increasingly important as climate change expands the areas where mosquitoes can survive.
The tiger mosquito, which can spread the chikungunya virus, is already appearing in new regions. Last year, chikungunya was reported for the first time in France’s Alsace region.
“More and more people are exposed to this risk,” said Simard.