Increase in dengue cases in France and the EU: how to explain this upsurge ?

Hausse des cas de dengue en France et dans l’UE : comment expliquer cette recrudescence ?

L’Union européenne et la France enregistrent une hausse significative des cas de dengue. Le Centre européen de prévention et de contrôle des maladies rappelle le besoin urgent de contrôler les populations de moustiques tigres, vecteurs de la maladie.

Figures which are not reassuring as the Olympic Games approach. Since January 1, 2024, 2,166 imported cases of dengue have been recorded in mainland France. For comparison, over the last five years, the number of imported cases stood at 128, between January 1 and April 30. The year 2024 will therefore have 16 times more cases than previous years over the same period. And just between May 1 and June 11, 500 imported cases of dengue fever were identified in France. These figures are high even though the tiger mosquito season is just beginning and the millions of visitors expected for the Olympic Games have still not arrived…

The risk ? A significant number of imported cases could lead to a chain of transmission in mainland France, the tiger mosquito being widely established there. As a reminder, this viral disease is most often benign, but its severe form can be serious and lead to death.

Rise in the European Union

The numbers are also climbing in the European Union, according to the European Center for Disease Prevention and Control. In 2023, 130 cases of indigenous dengue fever were reported, compared to only 71 in 2022. A significant increase compared to the 73 cases of dengue fever detected in the European Union over the period 2010 – 2021! Same trend for imported cases with 4,900 imported cases in 2023 compared to 1,572 in 2022, the highest number since the start of surveillance in 2008 in the European Union.

And for 2024 ? "In the first months of 2024, several countries reported a substantial increase in the number of imported dengue cases, which could suggest that the numbers in 2024 could become even higher", notes the ECDC in a press release.

An epidemic in the Americas

What is the cause of this significant increase in cases of dengue fever ? An epidemic raging in Latin America and the Caribbean. Indeed, in 2023, the WHO Americas region reported 4.5 million cases. And the year 2024 will be "probably the year of the worst dengue season ever recorded in America",Jarbas Barbosa, director of the Pan American Health Organization (PAHO), explained during a press conference. The epidemic also concerns Martinique and Guadeloupe, where 82% of dengue cases imported into mainland France come from.

A continued spread of tiger mosquitoes

At the same time, the spread of tiger mosquitoes continues in the European Union. Well established in almost all French departments, it is also established in twelve other EU countries. Another species, Aedes aegytpi, also vector of dengue, chikungunya and Zika but also of yellow fever, is established only in Cyprus but worries European health authorities. "Its potential for establishment in other parts of Europe is of concern due to its significant ability to transmit pathogens and its preference for blood human. The Culex pipiens, a common mosquito predominant in mainland France, is the vector of the West Nile virus.

Populations of these insects are expected to continue to grow. "It is widely expected that climate change will have a considerable impact on the spread of mosquito-borne diseases in Europe, for example by creating favorable environmental conditions for the establishment and to the growth of mosquito populations, prevents ECDC.

This underlines the importance of developing effective tools to manage mosquito populations while respecting the environment. She also recalls individual actions to combat mosquitoes at your own level: the systematic elimination of stagnant water, in your garden, on your balcony or terrace.

Note: 713 indigenous cases of West Nile virus were reported in 2023. This is less than in 2022 but more areas are affected: 123 in nine European countries, including 22 which declared a first case in 2023. "The number of affected regions is the highest since the 2018 peak , which indicates a wide geographic circulation of the virus, underlines the ECDC.