2023-07-10 23:59:04
He arrived on the territory silently. The tiger mosquito landed in Europe, then in metropolitan France in 2004, traveling on board a shipment of used tires from Asia. It now colonizes 71 metropolitan French departments. And can transmit serious diseases like chikungunya, dengue and Zika. Tuesday, July 11, the Weekly epidemiological bulletin Public Health France (SPF) identified a record number of dengue cases in 2022.
A dramatic increase in dengue fever cases
“It is the virus that circulates the most in the world among the three transmitted by tiger mosquito bites”, explains Yannick Simonin, virologist at the University of Montpellier. Last year, 378 people returned to the territory already infected with dengue, against 23 with chikungunya and six with Zika. These imported cases favor autochthonous cases, that is to say transmissions due to a bite on the territory. For dengue fever, in 2022, there were 66 – a figure that is rising sharply but which remains extremely low compared to the number of bites. “This is more than double the number of cases in the past fifteen years”, explains the specialist. The Provence-Alpes-Côte d’Azur region is the most affected.
What do we know about these diseases? Dengue is asymptomatic in 50 to 90% of cases. When symptoms appear, the elderly and young children are most at risk for the disease, which can cause fever, widespread pain and a rash. If the majority of infected people do not keep any sequelae, in rare cases, “Dengue fever can cause internal bleeding and directly affect vital organs such as the heart and liver”says Denis Malvy, member of the Committee for monitoring and anticipating health risks (Covars).
Zika, in the viewfinder of the WHO
It is rarer for people infected with chikungunya to have no symptoms. His name actually means “the disease of the bent man”, both the joint and muscle pain it causes can be debilitating, to the point of causing poor posture several months after infection.
The tiger mosquito is present in 71 departments in France. / Visactu
“Zika is often not very symptomatic, but if a pregnant woman is affected, it prevents the brain of the fetus from developing”, emphasizes Denis Malvy. After a major epidemic in Latin America in 2016, it is now one of the ten priority viruses to monitor for the World Health Organization (WHO).
No treatment has been proven
For now, only a vaccine against dengue exists since 2015, “but he has not proven himself”, deplores Denis Malvy. No more advances on the treatment side. For all three illnesses, only medications to alleviate symptoms are prescribed. But a new dengue vaccine that is raising great hopes should enter the trial phase before the end of the year. “Drugs to prevent severe forms, especially for the most fragile, are also being studied”indicates the infectiologist.
In the meantime, faced with the proliferation of the tiger mosquito this summer, doctors, pharmacists and gynecologists are on the go to quickly diagnose people infected with one of these viruses. But the common mosquito called Culex pipiens, louder and more lively than the tiger, also worries the health authorities. Last year, cases of West Nile fever due to its bites were reported in Aquitaine. In addition to being able to cause neurological damage in humans, this virus also affects “horses and birds that perpetuate the presence of the virus”says Denis Malvy.
The culex mosquito also affects animals
Without treatment, protecting yourself by limiting the development of these insects remains the priority lever. The installation of the tiger mosquito depends solely on human habits, and the simple fact of emptying a container containing stagnant water that can accommodate its eggs, can considerably slow down its establishment.
The common mosquito makes it more difficult to control viruses by infecting animals, and takes advantage of global warming to proliferate. For scientists, the diseases it transmits will be increasingly present in France. However, “we should not be unduly alarmed, the chances of being infected by a virus following a bite are still very low”tempers Yannick Simonin.
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Protect against stings
To prevent mosquitoes from entering the home, the government recommends installing mosquito nets on exterior windows. Fans also help keep them away.
Wear loose, long and bright clothes, also reduces the risk of bites. During walks with a child, a suitable mosquito net can be installed on a stroller.
However, repeated use of insecticides is not recommended. Health authorities also point out that essential oil-based skin sprays have a very short-term effectiveness. Their use on children should also be avoided.
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