Why do mosquitoes bite some people more than others?

Mosquito on a person's arm PHILIPPE HUGUEN / AFP Why are some people like "magnets" to mosquitoes, while others seem to shake them off? According to scientists, who are still working to decode their mechanisms, behind this — sometimes fatal — attraction lies a complex and variable chemical mixture. "Out of the just over 3,500 known species of mosquitoes, about a hundred bite humans and half a dozen are vectors of diseases" such as malaria, dengue, yellow fever, chikungunya, zika, or West Nile virus, Frédéric Simard, research director at the Institute for Research for Development (IRD) in southeastern France, explains to AFP. And "it is not a myth: we are not all equal in the face of mosquitoes' appetite. But we are not magnets all the time either," added this medical entomologist. Humans attract these tiny vampires, among which is the already famous tiger mosquito, through multiple sensory cues, primarily body odors, carbon dioxide from breath, and heat, experts agree. Female mosquitoes — the only ones that bite — detect these through specialized receptors, and that is how they choose their target. "We have known for over 100 years that mosquitoes are attracted to the carbon dioxide we exhale: it is the first signal that triggers their behavior, from several tens of meters away," Rickard Ignell, author of a recent study on the chemical foundations of these insects' differential attraction to human breath, explained to AFP. At about 10 meters, "mosquitoes begin to detect our odor which, combined with CO2, attracts them even more," added this Swedish scientist. Popular beliefs However, several popular beliefs about what attracts these dipterans have been debunked. "The difference between blood types does not have a solid scientific basis: some studies have been carried out, but with very few people.

Nor is it related to skin, eye, or hair color," listed Simard from the IRD. A fundamental factor of attraction is undoubtedly smell, "a mixture of molecules produced by our microbiota that is more or less attractive to mosquitoes," agreed the entomologist. Humans emit between 300 and 1,000 different odorant compounds, according to various studies, but scientists are only just beginning to better identify which ones attract these tiny blood-sucking animals. For the research in which Ignell participated, the difference in the degree of attractiveness of 42 women to "Aedes aegypti" mosquitoes — vectors of yellow fever or dengue, among other diseases, in vast regions of Latin America — was evaluated in a laboratory. "We demonstrated that a mixture of odorant compounds — we identified 27 that these mosquitoes can detect — influences the degree of attraction," according to the scientist. "Women most attractive to mosquitoes, especially those in the second trimester of pregnancy, produced slightly more of a compound derived from sebum breakdown," he noted. Precisely, the fact that such a small increase in the released dose of 1-octen-3-ol, also known as fungus alcohol, changes the behavior of these insects was one of the surprises, Ignell revealed, adding that "mosquitoes are fascinating creatures." Now on g1 Watch out for alcohol Drinking beer, which increases body temperature, the amount of exhaled CO2, and modifies skin odors, can also contribute to attracting them more, according to some studies. One standardized study conducted in Burkina Faso with volunteers who drank a local beer and, a few days later, the same amount of water, demonstrated that the Anopheles mosquito, the main vector of malaria, was more attracted to the odors of those who had consumed the alcoholic beverage. These mechanisms fuel growing research as health threats related to some of these insects expand. The tiger mosquito, in particular, is expanding into areas where it was not endemic due to global warming, urbanization, and globalization. "The risk affects more and more people, and also more countries where there is money to protect oneself, which generates funding and research results," Simard asserted. When mosquitoes are buzzing around, it is recommended to protect yourself from bites with long, loose clothing, mosquito nets, or repellents. "And try to eat lightly and consume alcohol in moderation," the scientist added. Why do mosquitoes bite some people more than others? PHILIPPE HUGUEN / AFP READ ALSO: Mental confusion and irritability can be signs of vitamin B12 deficiency; understand why a diet with meat does not eliminate the risk.