Why do some people get bitten by mosquitoes more than others?

Some people can sit outside all summer and not get any painful and annoying mosquito bites. 

Then you have the rest of people who smear themselves with mosquito protection and still get bitten over and over again by mosquitoes. You might be wondering why this happens?

The truth is, it all depends on the invisible chemical landscape of the air around us. Mosquitoes take advantage of the environment through specialized effective sensory organs to find victims by following the subtle chemical traces left by our bodies. 

Mosquitoes rely on carbon dioxide to find their hosts. When we exhale, the carbon dioxide in our lungs does not immediately mix with the air. It lingers like a little cloud which mosquitoes follow like a breadcrumb.

“The mosquitoes begin to orientate themselves towards these carbon dioxide impulses and continue to fly into the wind as they perceive concentrations higher than those contained in normal ambient air,” says Joop van Loon, an entomologist at Wageningen University in the Netherlands. 

One human being produces approximately one kilogram of CO2 every day and every time he/she exhales, approximately 13 times per minute, he emits more than one hundred milligrams of this gas. Mosquitoes detect the current with pulses of CO2, which varies between adults ( more carbon dioxide when breathing) and children (less carbon dioxide when breathing) depending on diet and physical exercise. 

The lactic acid we emit when breathing or when sweating also attracts these insects. Tall people and pregnant women emit more lactic acid and CO2, so they are perfect ‘targets’ for active mosquitoes. People who have just done a lot of physical exercise are also very attractive to insects. 

It all gets serious when mosquitoes are about a metre away from a group of possible targets. In confined spaces, mosquitoes take into account many factors that vary from one person to another; factors such as skin temperature, the presence of water vapor, and colour.

Scientists believe that the most important variable to which mosquitoes are attracted to is the chemical compounds produced by the colonies of microbes that live on our skin.

These chemical packages are complex, including more than 300 different compounds and they can vary depending on the person and depending on the genetic variation and the environment.

These chemical packages are complex, including more than 300 different compounds, and vary from person to person depending on genetic variation and the environment, as we say.

For example, men with higher skin microbial diversity tend to have fewer mosquito bites than men with fewer skin microbes, according to a 2011 study in the journal PLOS ONE. In addition, the researchers found that men with less diverse microbes tended to have the following bacteria in their bodies: Leptotrichia, Delftia, Actinobacteria Gp3 and Staphylococcus.

In contrast, one study found that men with a wide variety of microbes tended to have the bacteria Pseudomonas and Variovorax on their skin.

Subtle differences in the composition of this chemical cocktail may explain the large variations in the number of bites or stings a person receives. The composition of these microbial colonies can also vary over time in the same individual, particularly if that person is ill.


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