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Public Health France warns of a significant increase in cases of autochthonous dengue fever (not imported from countries where the virus circulates) in 2022. Even if this phenomenon was foreseeable in the south of France, the National Public Health Agency describes the situation as “exceptional”.
In 2022, 378 imported cases of dengue fever, 23 of chikungunya and 6 of Zika were recorded in metropolitan France. These diseases are transmitted to humans through the bites of Aedes albopictus type mosquitoes carrying the virus, more commonly known as tiger mosquitoes. They mainly occur in tropical and subtropical regions. While most of the cases notified in mainland France concern people who have traveled to these areas, there are more and more so-called “indigenous” cases, that is to say not imported.
Nine episodes of indigenous dengue transmission in 2022
Thus, nine episodes of autochthonous transmission of dengue totaling 66 cases in total, were observed in 2022. Among them, five occurred in Occitanie (12 cases), three in Provence-Alpes-Côte d’Azur (52 cases) and one in Corsica (two cases). “Six of these episodes occurred in departments where no autochthonous case had been previously reported”, says Public Health France. This phenomenon of an increase in autochthonous dengue cases was to be expected because the Aedes albopictus mosquito has been implanted in mainland France since 2004 and the area where it occurs continues to expand. However, the National Public Health Agency estimates that “the situation was exceptional” in 2022 given the number of episodes, their intensity and the geographical areas concerned.
A surveillance system in jeopardy?
She is even concerned about the viability of the monitoring system put in place since 2006. This consists of monitoring imported and indigenous cases of dengue fever, chikungunya and Zika by making the declaration of biologically documented cases compulsory. This surveillance is reinforced between May and November, in particular by the analysis of laboratory data making it possible to identify undeclared cases and guides the application of control measures (preventing mosquitoes from proliferating).
What are the symptoms of dengue fever?
Dengue fever causes high fevers associated with headaches, body aches and a feeling of fatigue. In the majority of cases, the disease can be treated at home with analgesics (there is no specific treatment against dengue, nor a vaccine). But sometimes the disease can progress to severe forms (dengue hemorrhagic fever in the event of repeated infections). According to the World Health Organization (WHO), 50 million people are infected with the dengue virus each year, including 500,000 cases of dengue hemorrhagic fever, which are fatal in more than 2.5% of cases.