In France, and particularly during the summer months, mosquitoes are a noticeable presence. These insects, although essential in the food chain, are often perceived as major nuisances. Why do mosquitoes bite us? Are bites dangerous? And above all, is it possible to remedy this scourge?
Understanding the mechanism of bites
In reality, only a tiny minority of mosquitoes are adapted to human living conditions and colonize cities. It is the females that feed on blood, and therefore bite. This hematophagous behavior proves vital for the maturation of their eggs. They are also the ones that emit this characteristic noise.
How do mosquitoes spot us?
These insects have a set of senses to locate their hosts, based on three key elements:
- Body odors . Mosquitoes have extremely sensitive olfactory receptors that allow them to detect odors emitted by human beings. Certain chemical compounds such as sweat, steroids or even urine particularly attract them.
- Carbon dioxide (CO2) . During the normal breathing process, we exhale carbon dioxide. This CO2 is thus released into the atmosphere. Mosquitoes are able to sense these high levels of CO2 to locate potential hosts.
- Body heat.
These sensory abilities explain why some people are more prone to mosquito bites than others. For example, pregnant women generally emit more heat and carbon dioxide, making them particularly attractive to these insects.
Why this itchy feeling?
After being stung, a local reaction usually occurs. This reaction is due to the release of vasoactive mediators following the effect of components of mosquito saliva on mast cells. This leads to itching, papules (skin lesions) and erythema, forming the Lewis triad. Although normal reactions usually disappear within a few hours, more concerning reactions may occur.
The dangers of mosquitoes
A public health problem
In France, the tiger mosquito is the species capable of carrying certain diseases . It is also now permanently established in more than 70 departments of the metropolis. It is by biting an infected person or animal that the insect ingests the parasites, viruses or bacteria present in the blood. After a few days of incubation, the infected insect can then transmit the pathogen to another person through its bite . The tiger mosquito can transmit diseases such as dengue fever, malaria, yellow fever and the Zika virus.
Other risks
These mosquito bites can also trigger a range of reactions, from itching and swelling to more severe allergic reactions . Interestingly, the body can develop some immunity to mosquito bites over time, thereby lessening the reactions. However, there are also risks, including the possibility of secondary infection with bacteria from dirty hands or excessive scratching. In addition, the injection of saliva by the mosquito during the bite can cause local irritation which, in some cases, can progress to allergic hypersensitivity . And, although rare, there is a risk of anaphylactic shock in reaction to a mosquito bite. However, it is important to note that unlike some other insect bites, mosquitoes do not inject venom, making anaphylactic shock even rarer. To combat these problems, the best method remains to limit the risk of bites.
How to get rid of mosquitoes?
There are several measures to reduce the risk of mosquito bites. In particular, we can:
- Wear covering clothing to reduce exposed areas.
- Eliminate points of stagnant water . Mosquitoes usually lay eggs in stagnant water. Removing these breeding sites therefore makes it possible to reduce their population.
- Use repellents .
- Install mosquito nets on doors and windows.
Unfortunately, even by implementing preventive measures, it remains impossible to completely eliminate the risk of stings. This is why using soothing products can significantly reduce the unpleasant symptoms associated with mosquito bites.
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Feuillet-Dassonval C. Lavaud F. Viniaker H. Bidat E. Archives de pédiatrie volume 13. (2006). Allergic reactions to mosquito bites, what prevention? https://sofia2.medicalistes.fr/IMG/pdf/reaction_allergique_aux_bites_de_moustiques.pdf
Ministry of Health and Prevention. (April 2023). Disease-carrying mosquitoes . https://sante.gouv.fr/sante-et-environnement/risks-microbiological-physical-et-chemicals/especes-nuisibles-et-parasites/moustiques
