In an opinion dated April 3, 2023, the Committee for monitoring and anticipating health risks (Covars) predicts an increase in cases of dengue fever, Zika and chikungunya in metropolitan France in the coming years. Blame it on “Aedes albopictus”, the famous tiger mosquito, small, white and black striped, silent and diurnal.
Since 2010, the number of departments it has colonized has multiplied by 10, according to a report by the National Assembly, cited in the Covars report. In 2023, the tiger mosquito was established and active in 68 metropolitan departments and spotted punctually in seven other departments over 5 years, according to the Vigilance-moustiques site. Observed for the first time in the Alpes-Maritimes in 2004, the insect continues since its progression in metropolitan France, from the South to the North.
The mosquito is the vector of many diseases. Today in the world, four billion people are exposed to the risk of dengue fever. “In 2019, the WHO considered dengue fever to be one of the 10 major threats to global health and currently estimates the number of annual dengue cases at between 100 to 400 million”, underlines the Covars. It is believed to be responsible for 400,000 deaths worldwide each year.
Towards new foci of dengue fever, chikungunya and Zika
In 2022, 65 cases of autochthonous dengue were recorded in France. The number of cases of arboviruses – these viral diseases transmitted by arthropods including mosquitoes – imported into mainland France, has multiplied by 4.5 between 2015 and 2019, according to figures from Public Health France.
“We must therefore expect an increase in cases in mainland France over the coming summers, although of a magnitude that is difficult to anticipate, and new outbreaks of dengue fever, chikungunya and Zika on all French territories”, writes the Covars in his opinion.
As a reminder, mosquito bites are only the fact of the female. This takes the pathogen by feeding on the blood of an infected person or animal and transmits it, through saliva, during a subsequent meal.
Climate change in question
The spread of mosquito vectors of these diseases can be explained in particular by the rise in temperatures. Thus, according to Covars, climate change promotes in Europe, “better survival of Aedes females, an increase in the number of generations and a greater period of annual activity, an increase in mosquito populations, faster development infectious agents in the body of mosquitoes, and an increase in human/vector contact”.
Massive population movements during major international events would also increase the risk of the spread of arboviruses. In the viewfinder of Covars, the Rugby World Cup in the summer of 2023 and the Paris Olympics 2024: “the upcoming conjunction of major international sporting events in mainland France during the summer season, generating significant migrations of populations from around the world increases the risk of outbreaks of dengue fever, Zika and chikungunya”.
Simulations ahead of major sporting events
As such, Covars recommends preparing for these events by simulating the triggering of the Orsec plan, “for example by simulating 20 outbreaks and 200 cases in PACA and 20 outbreaks and 200 cases in Occitania in 2023”. Another proposal: to simulate the occurrence of five dengue outbreaks around five Olympic Games sites.
More generally, Covars pleads for better training of health professionals on these arboviruses and better management of serious forms. It also recommends strengthening the vaccine strategy, against dengue fever in particular, and emphasizing research into new vaccines.
It also seems essential to raise people’s awareness of the risks and to act collectively on surveillance and prevention. Thus, among good practices, it is imperative, at home, to hunt stagnant water, places where females lay their eggs.
Source: Covars notice of April 3, 2023, Vigilance-mosquitoes