Mosquitoes: The Scientific Reasons Why You Get Bitten More

07:09

Why do some people seem to be the prime targets for mosquitoes while others enjoy a relatively peaceful evening? The explanation does not lie in an alleged "quality" of their blood. These insects combine multiple cues to locate their targets, from exhaled air to body temperature, as well as skin chemistry.

As night falls, the scenario often repeats itself: several people gather in the same place, but only one spends their time swatting away mosquitoes. This feeling of being a "privileged target" is not entirely subjective. Mosquitoes do indeed use several signals to choose which humans they will approach.

And contrary to a widely held belief, this phenomenon cannot be simply explained by a supposed "sweet blood".

It All Starts with Breath

For a mosquito in search of a blood meal, carbon dioxide is a particularly important signal. Each exhalation releases CO₂ into the environment, creating a sort of trail that the insect can detect from a distance.

A person who breathes more heavily can therefore produce a signal that is more easily detectable. This is especially true during or after physical exertion. Pregnancy can also alter breathing and metabolism, which is part of the reason why pregnant women may be more exposed to mosquitoes.

But CO₂ is just the beginning of the process. Once the insect gets closer to its potential host, other information takes over.

Skin Has Its Own "Signature"

At close range, body odor becomes crucial. Sweat contains various molecules that can attract mosquitoes, including certain compounds produced in greater quantities after exertion or when temperature rises.

However, two people placed under the same conditions do not necessarily have the same olfactory signature. Genetics, metabolism, and individual characteristics influence the composition of substances present on the skin's surface.

This is why one person can accumulate bites while another, sitting just a few centimeters away, seems much less affected.

Bacteria on the Skin Play a Role

The surface of our skin is also an ecosystem. Billions of microorganisms naturally live there and participate in the transformation of certain substances found in sweat.

These reactions produce volatile molecules that contribute to body odor. However, this composition varies significantly from person to person.

Scientific studies have thus looked into the role of the skin microbiome and certain compounds, notably carboxylic acids, that may influence an individual's attractiveness to mosquitoes.

The difference between two people could therefore also play out on a microscopic scale.

Blood Type Is Not Completely Negligible

Blood type has also been studied as a potential factor. Some research has observed a preference among certain mosquitoes for blood type O over others.

However, this does not mean that the insect "guesses" the blood type before biting. The selection relies on all the signals available around the body and on its surface.

Blood type should therefore be considered as one factor among others, and not as the sole explanation for the number of bites experienced.

Heat and Clothing Can Make a Difference

As it approaches its target, the mosquito also uses visual and thermal information. Body temperature is particularly useful for locating an accessible area.

Clothing plays a role as well. Very dark colors can make a person more easily detectable under certain conditions, while loose and covering clothing mechanically reduces the amount of exposed skin.

This is obviously not an absolute protection, but it can help reduce the risk of bites.

Can You Change Your "Target" Profile?

It is difficult to modify the biological characteristics that make a person more attractive to mosquitoes. Body odor partly depends on genetic factors and the unique functioning of the body.

Changing perfume, soap, or altering one's diet does not offer any guarantees. Reactions can even vary significantly from one person to another.

The most effective strategy is rather to limit contact with the insects: using appropriate repellents, wearing covering clothing, installing mosquito nets, and eliminating stagnant water around the home.

Ultimately, being bitten more than those around you has nothing to do with a supposed "bad blood". It is mainly the result of a complex combination of chemical, thermal, visual, and biological signals that allow the mosquito to locate its host.