The tiger mosquito is now established and active in 81 mainland French departments. Its constant progression year after year is transforming a simple summer nuisance into a real public health issue. Because beyond daily annoyances, the tiger mosquito is a vector for viral diseases: dengue, chikungunya, and Zika. Since 2010, autochthonous transmission cases have been recorded every year in mainland France, proving that the risk is now very real. Specifically, the mosquito can contract one of these diseases by biting an infected person returning from a trip to tropical areas where these viruses circulate. After 2 to 3 days, it can transmit the virus by biting another person, and it can do so throughout its life cycle (one month).
What diseases can the tiger mosquito transmit?
Beyond being a nuisance, the tiger mosquito can transmit several viral diseases through its bites.
The main diseases transmitted are:
- Dengue
- Chikungunya
- Zika
These diseases are caused by viruses that are transmitted from person to person primarily through the bites of mosquitoes of the genus Aedes, which includes the tiger mosquito.
Dengue, chikungunya, Zika: what are the differences?
Dengue manifests as high fever, intense headaches, muscle and joint pain, sometimes accompanied by a skin rash. In rare cases, it can progress to a severe hemorrhagic form. Chikungunya is characterized by sudden fever and very intense joint pain, sometimes debilitating and potentially lasting several months. Zika is distinguished by a skin rash, moderate fever, and conjunctivitis. Its main danger lies in the infection of pregnant women, which can lead to congenital malformations in the fetus.
Note: other mosquitoes of the genus Aedes can also transmit these viruses, but they are not currently present in mainland France.
Climate Change: An Accelerator of Spread
Global warming plays a major role in the expansion of the tiger mosquito and the increased risk of transmission in mainland France. Milder winters promote better survival of diapausing eggs, while hotter and longer summers accelerate the insect's development cycle. The tiger mosquito's active period lengthens, as does the virus's replication window within the insect. Higher temperatures also make the mosquito infectious more quickly. Ultimately, a large part of French territory could become favorable for the permanent establishment of the tiger mosquito and viral circulation.
Risk areas: Overseas territories and travelers
The tropical zones where these viruses circulate are vast and include a majority of French overseas departments and territories. Metropolitan France is therefore exposed due to the significant number of travelers who visit these regions each year.
The tiger mosquito, now established and active in 81 departments, can thus create an epidemiological bridge between endemic areas and mainland France.
Imported cases and autochthonous cases: what is the situation in mainland France?
The interplay between these two types of cases is central to epidemiological surveillance.
2025 Season: a record year
The year 2025 saw unprecedented viral circulation in metropolitan France. According to data from Santé publique France, several dozen episodes of autochthonous transmission were identified, totaling several hundred cases across the country. The Provence-Alpes-Côte d'Azur region was particularly affected, reporting over 450 autochthonous chikungunya cases alone during the season. Dengue also circulated, with autochthonous outbreaks detected in the south of France.
Regarding imported cases, the pressure was particularly high due to active epidemics in French overseas territories: 932 imported chikungunya cases (the majority from Réunion) and 775 imported dengue cases (mainly from the Antilles) were recorded. In total, over 1,700 imported cases were reported during the surveillance period.
An autochthonous case refers to a person who contracts the disease without having stayed in an area where the virus is actively circulating within two weeks prior to symptoms. The contamination therefore occurred locally, through the bite of an infected tiger mosquito in mainland France.
Imported cases involve individuals infected during a stay in an intertropical zone (Overseas territories, Asia, Africa, South America), who return to mainland France already infected. These cases are reported annually in the country and represent the main risk of virus introduction.
These episodes show that the virus regularly arrives in the country and that local transmission can occur when the conditions are met: presence of the tiger mosquito, favorable temperature, and arrival of an infected traveler.
Symptoms: how to recognize these diseases?
Not all individuals infected with one of these viruses present symptoms (variable proportion depending on the virus). However, when they do manifest, the signs may include:
- High fever (> 38.5°C) with sudden onset
- Muscle and/or joint pain (sometimes intense in chikungunya)
- Headaches
- Skin rash (as in dengue or Zika)
- Absence of respiratory signs or other infectious warning signs
If you return from a risk area and develop these symptoms, it is imperative to consult a doctor and mention your recent travel.
How to protect yourself when traveling?
To limit the risk of infection and the introduction of the virus into mainland France, health authorities recommend:
- Use appropriate skin repellents
- Sleep under a mosquito net
- Wear long, loose-fitting clothing
- Eliminate stagnant water around your living area
Upon your return to France, if you develop a fever within 15 days, consult a doctor promptly.
Conclusion: Essential Vigilance Against an Expanding Vector
The tiger mosquito is now established and active in 81 departments of mainland France. This expansion, coupled with the influx of travelers from tropical areas, makes the risk of transmission more real than ever. Since 2010, the regular presence of autochthonous cases each year confirms that local transmission is no longer an exception. The year 2025 marked a turning point with an unprecedented level of viral circulation in mainland France.
Frequently Asked Questions (FAQ)
Does the tiger mosquito pose a health risk?
Yes, because it can transmit viruses such as dengue, chikungunya, and Zika. Not everyone who is bitten necessarily develops symptoms, but the risk of transmission exists, especially when the mosquito has previously bitten an infected traveler returning from a tropical area. In the vast majority of cases, these diseases resolve spontaneously without complications.
Can you catch the same disease multiple times?
Yes. For dengue, for example, there are four different serotypes. A first infection confers lasting immunity against that specific serotype, but not against the other three. A second infection by a different serotype can even increase the risk of severe forms.
Does a mosquito bite automatically mean contamination? Should you consult a doctor?
No, a bite does not systematically lead to virus transmission. However, if you develop symptoms such as sudden fever, joint pain, or a rash in the days following a bite (especially after returning from travel in a tropical area), consult a doctor and inform them of your trip. Avoid taking aspirin or ibuprofen without medical advice.
Can the tiger mosquito transmit Covid-19 or other diseases?
No. The tiger mosquito only transmits certain specific viruses: dengue, chikungunya, and Zika. It is not a vector for Covid-19, HIV, or most respiratory viruses.
