Each year, enhanced seasonal surveillance for cases of chikungunya, dengue, and Zika—coordinated by Santé publique France—is activated from May 1 to November 30, in addition to the annual surveillance based on mandatory reporting. These viral diseases, transmitted by mosquitoes of the genus Aedes, are primarily tropical but can be transmitted in Europe and mainland France by the Aedes albopictus mosquito (also known as the tiger mosquito), which is established in most departments and continues to spread across mainland France. The first locally transmitted cases of dengue and chikungunya in mainland France were observed in 2010. Since then, these outbreaks have recurred and have become a regular occurrence each year.

The year 2022 was marked by an increase in locally transmitted dengue cases, with 9 outbreaks identified totaling 65 cases. These cases were distributed across Occitanie, Provence-Alpes-Côte d’Azur, and Corsica, and outbreaks occurred in departments previously unaffected, such as Corsica, Pyrénées-Orientales, Hautes-Pyrénées, and Haute-Garonne. These outbreaks are likely to recur, increase in scale, and affect new departments. Climatic conditions favorable to mosquito proliferation—including extreme heat, heavy rainfall, flooding, drought, and global warming—as well as urbanization, increased travel, and globalization are among the factors contributing significantly to this trend.

Key figures on cases of chikungunya, dengue, and Zika since May 1, 2023

From May 1 to 26, 2023, the following were identified in mainland France:

• 46 imported cases of dengue diagnosed in departments with documented populations of Aedes albopictus

• 1 imported case of chikungunya

• 0 cases of Zika

In addition to the situation in mainland France, active dengue outbreaks have been identified in Martinique and Guadeloupe, and the WHO has reported a resurgence of chikungunya and dengue cases in Latin America (among travelers departing or returning from the region).

Map of the departments where the tiger mosquito is present as of January 1, 2023

What does the surveillance of arboviral diseases—dengue, chikungunya, and Zika—entail?

Annual surveillance of arboviruses is based on mandatory case reporting. In addition, from May 1 to November 30, during the active season of mosquito vectors, Santé publique France coordinates enhanced seasonal surveillance of arboviruses in metropolitan France, in collaboration with the Regional Health Agencies and the National Reference Center. As part of this effort, the Agency publishes weekly data on the number of cases diagnosed nationwide. Specific regional updates are also published in regions where the tiger mosquito is established.

• Learn more about the surveillance mission

How can you avoid getting infected?

The infection is transmitted by an infected mosquito (which has previously fed on the blood of an infected person) that can, upon biting another person, transmit the virus to a new host. An infected person is “contagious to mosquitoes” while the virus is present in their blood (the viremic phase, lasting about ten days).

To protect yourself and avoid mosquito bites in regions where cases of chikungunya, dengue, or Zika have been reported, follow these precautions:

• wear loose-fitting, covering clothing;

• use mosquito repellents;

• sleep under a mosquito net;

• plug in electric mosquito repellent diffusers;

• use mosquito coils outdoors.

What are the health recommendations for travelers coming from or returning to regions where the virus is circulating?

These viruses circulate throughout the intertropical zone but can also be transmitted in temperate zones by the Aedes albopictus mosquito.
For 15 days after returning from regions where cases have been reported, it is recommended that you:

• see a doctor if you have a fever and tell them which regions you are returning from;

• continue to protect yourself against mosquito bites to prevent an Aedes mosquito from biting you and, in turn, becoming infected with the Chikungunya, Dengue, or Zika virus. It could then transmit the virus to others through a bite.