Toulouse, Nîmes, Nantes, and now Paris... Mosquito control operations are multiplying. After the 13th arrondissement of Paris and Colombes (Hauts-de-Seine), it is the 15th that has been infected, with not two, but three cases of dengue, coming straight from Martinique, according to our colleagues from Le Parisien. On the instructions of the Regional Health Agency (ARS) and the town hall of the district, a mosquito control operation took place on the night of Friday 15 to Saturday 16 September. A manager? The tiger mosquito, whose proliferation is dazzling, especially in Ile-de-France.
Dr. Louis Lambrechts, research director and head of the Virus-Insect Interactions Unit at the Institut Pasteur, explains to Le Figaro the peculiarities of the tiger mosquito.
Le Figaro- Many testimonies point to the unusual and massive presence of mosquitoes throughout the France. Is the tiger mosquito involved?
Louis Lambrechts.- Yes, the tiger mosquito is becoming a real nuisance and its geographical expansion is inevitable. In recent decades, it has invaded a large number of countries including the France. Arrived in 2004 in Menton and in 2015 in Île-de-France, it is now present in all regions, except Brittany. For the time being, 71 departments are colonized, it is very likely that in a few years, the Aedes Albopictus will be present on the entire French territory.
What are the characteristics of the tiger mosquito?
The tiger mosquito is native to Southeast Asia. Beyond the bites and unpleasant itching, the tiger mosquito is mainly a vector of viruses that do not circulate in metropolitan France such as dengue, chikungunya or the Zika virus.
How do these viruses appear in France?
They are imported by travelers returning from Guadeloupe or Southeast Asia. It is enough for a person who has contracted dengue fever in these areas to enter France with the virus in his blood and be bitten again by a tiger mosquito when he returns. This one, vector of the virus, can transmit it again by biting someone else. The French who has not traveled will not suspect that he can be affected by this virus. These are called indigenous cases, where there has been local transmission. In 2022, there was a record number of autochthonous dengue cases with more than 60 cases.
Is this proliferation also explainedby climate change?
The mosquito is very dependent on the outside temperature, it can not grow in winter. With the increase in temperatures that we are experiencing, the period of activity of the tiger mosquito is longer and longer. In addition, when it is hot, the virus incubates faster in the mosquito and the transmission of a pathology such as dengue fever occurs more quickly. However, ecological models predict that it could take root in France even in the absence of global warming. But rising temperatures favor the establishment of this invasive species.
Regarding the transmission of viruses, one of the main factors is the overall increase in the movement of people, especially by air. Viruses such as dengue fever can now be imported into France year-round.
Is mosquito control an effective solution to combat the spread of viruses?
Mosquito control is based on insecticides called pyrethroids, which kill adult mosquitoes. That is how outbreaks are stopped, but it is not sustainable on a large scale because these products are toxic to people and the environment. It is still better to be exposed to an insecticide very occasionally than to contract dengue. When you compare the cost and the benefit, it is indeed the best thing to do.
What would be the solutions to sustainably fight against the proliferation of the tiger mosquito?
Everyone can contribute to the establishment of a prevention system to limit the proliferation of tiger mosquitoes. Mosquitoes thrive in water. It is imperative to eliminate stagnant water that may be present in vases or rainwater tanks for example. If everyone makes the effort to eliminate these sites on their property, perhaps we will already minimize the risk and emergency interventions with pesticides.
More reactive imported case detection systems and stricter surveillance should also be put in place. Often, people who have contracted the virus do not know this, as symptoms do not appear until several days later. A general practitioner who sees a patient presenting with fever and body aches, if he does not think to ask if the person has traveled, will not think of chikungunya, dengue or Zika, which are very unusual pathologies for a general practitioner in metropolitan France.