“You’re going to be bitten by mosquitoes more during your vacation” (and here’s why)

The holidays are approaching and so are the increase in mosquito bites. These big itchy pimples can quickly become a nuisance during our moments of idleness and relaxation. Faced with this problem, many leave equipped with repellents and balms of all kinds in their suitcases. We should even use more anti-mosquito protection when we leave our home, according to the explanations of Professor Anna-Bella Failloux, professor of medical entomology at the Pasteur Institute.

Let us first remember that in the mosquito, it is only the female that bites. She inserts her proboscis into the skin and injects her saliva. Inside the latter are numerous molecules which make its composition very complex. “It is this cocktail of molecules which triggers an immune reaction and which, depending on the person bitten, will lead to inflammation causing this famous itchy pimple” the specialist explains to us. Several factors influence the composition of mosquito saliva, including their environment. For example, both male and female mosquitoes collect sugar from plants and fruits in their environment. This sugar intake is essential for them to be able to fly and conditions the composition of their saliva, but it varies depending on the places from which it comes, the plants being different depending on the place. We find this same variation with the blood on which mosquitoes feed. Our blood is not the same as that of our neighbors, and the latter also modifies the composition of their saliva.

“A person can thus have more or less attenuated reactions depending on their injection history (number and locations, editor’s note)”, the expert tells us. “A person bitten by the same species of mosquito in a given location develops immunity to the saliva that has often been injected.” Thanks to this immunity to mosquitoes in an environment, it is possible to no longer even feel their bites. But when we leave our environment, to go on vacation for example, we no longer have any immunity against the saliva of the mosquitoes present. There are just as many mosquitoes, but more bites and a potentially stronger reaction. “We always have the impression that there are fewer mosquitoes at home, even though there are just as many as at our vacation spots” concludes Professor Failloux.