A dazzling progression, and one which shows no signs of slowing down. The number of cases of dengue imported into mainland France, mainly after trips to the Antilles, has already broken the record reached for the whole of 2023, according to data from Public health France. From January 1 to April 30, 2024, 2,166 imported cases of dengue were recorded in mainland France, compared to 128 cases on average over the same period the previous five years.
Even before the Paris Olympic Games, which will encourage the mixing of populations in the middle of the tiger mosquito season, the 2023 record for imported dengue cases (2,019) was broken in just four months. And from May 1 to 14, when diseases linked to the period of activity of mosquito vectors began to be the subject of “reinforced surveillance”, 98 other cases of imported dengue fever were recorded in mainland France.
An outbreak of the epidemic in the Americas and the Caribbean
Dengue fever is a viral disease that is most often benign, which can progress, in approximately 1% of cases, to a more serious form, notably causing bleeding. Deaths are very rare. “Imported” cases concern people who have traveled to regions of the world where this virus transmitted by a tiger mosquito (Aedes albopictus) bite is endemic.
Nearly a month ago, health authorities already warned of an “unprecedented” situation, linked to the outbreak in the Americas and the Caribbean, and called for increased vigilance, especially in the run-up to the Olympic Games. The Pan American Health Organization (PAHO) for its part warned at the end of March that Latin America and the Caribbean should expect the worst dengue season on record, fueled by the El Niño climatic phenomenon.
No indigenous cases detected
During the first four months of 2024, 82% of cases imported into mainland France were contracted in Martinique or Guadeloupe and 5% in Guyana, “departments where there is a significant epidemic”, noted Public Health France on Wednesday evening.
In mainland France, dengue fever – an arbovirus, like chikungunya or Zika – is under reinforced surveillance between May and November, the period of activity of the tiger mosquito, now present in almost the entire territory. To date, only five imported cases of chikungunya and two imported cases of Zika have been detected in mainland France since the start of 2024, a far cry from the figures for dengue.
To date, no episode of indigenous transmission (person who has not recently traveled to a virus circulation area and has therefore become locally contaminated) of dengue fever, but also of chikungunya or Zika, has yet been detected. In 2023, France had recorded around fifty indigenous cases of dengue fever – transmitted by a mosquito present on site -, after a record of 66 in 2022.