Aedes albopictus (also known as the tiger mosquito) and Aedes aegypti are the main blood-feeding arthropods (which include insects and mites) that transmit an infectious agent (virus, bacterium, parasite) from one vertebrate to another" data-tooltip-title="blood-feeding arthropod (including insects and mites) that transmits an infectious agent (virus, bacteria, parasite) from one vertebrate to another" data-tooltip-content="" data-tooltip-placeholder-is-selection="true" data-tooltip-placeholder-is-selection-text="vector" data-tooltip-data="[{"tooltipTitle":"arthropod (including insects and mites) hematophagous (feeding on blood) that transmits an infectious agent (virus, bacteria, parasite) from one vertebrate to another","tooltipContent":"", “placeholderIsSelection”: “true”, “placeholderIsSelectionText”: “vector” }]">dengue vectors are present in several French territories. In this context, Santé publique France’s efforts focus on two main areas: surveillance and prevention.

Epidemiological Surveillance of Dengue

The epidemiological surveillance system for dengue is tailored to the various epidemiological situations and vector risks in mainland France and the overseas departments. It is part of the broader efforts to combat arboviral diseases.

In metropolitan France, surveillance of dengue (as well as chikungunya and Zika) is governed by Directive No. DGS/VSS1/2019/258 of December 12, 2019, regarding the prevention of arboviral diseases. This surveillance is based on:

The mandatory reporting of all biologically confirmed cases

Any case of dengue—whether imported or autochthonous—that is biologically confirmed (probable or confirmed) must be immediately reported to the ARS surveillance and alert unit by any appropriate means (phone, fax, email, reporting portal) and then reported using the mandatory reporting form.

Reporting criteria:

• Fever >38.5 °C with sudden onset 
• AND at least one pain-related symptom (myalgia ± arthralgia ± headache ± low back pain ± retroorbital pain) 
• AND at least one of the following laboratory criteria: positive RT-PCR OR positive NS1 test OR positive IgM OR seroconversion OR a fourfold increase in IgG levels between two samples taken at different times.

Enhanced seasonal surveillance in departments where the Aedes albopictus vector is present 

This surveillance is intensified each year, from May 1 to November 30, the expected period of activity for Aedes albopictus in the departments where this blood-feeding arthropod (which includes insects and mites) is present—a vector that transmits an infectious agent (virus, bacterium, parasite) from one vertebrate to another" data-tooltip-title="blood-feeding arthropod (including insects and mites) that transmits an infectious agent (virus, bacterium, parasite) from one vertebrate to another" data-tooltip-content="" data-tooltip-placeholder-is-selection="true" data-tooltip-placeholder-is-selection-text="vector" data-tooltip-data="[{"tooltipTitle":"arthropod (including insects and mites) blood-feeding (feeding on blood) that transmits an infectious agent (virus, bacteria, parasite) from one vertebrate to another","tooltipContent":"","placeholderIsSelection":"true","placeholderIsSelectionText":"vector"}]">vector. The goal is to enable rapid intervention by services responsible for all measures aimed at controlling and protecting against vectors of human pathogens (mosquitoes, lice, etc.) and monitoring them." data-tooltip-title="all measures designed to control and protect against vectors of human pathogens (mosquitoes, lice, etc.) and to monitor them." data-tooltip-content="" data-tooltip-placeholder-is-selection="true" data-tooltip-placeholder-is-selection-text="vector control" data-tooltip-data="[{"tooltipTitle":"all measures designed à for%control and à protection against vectors of pathogens that affect l’humans (mosquitoes, lice…) and their monitoring.","tooltipContent":"","placeholderIsSelection":"true","placeholderIsSelectionText":"vector control"}]">vector control (LAV) around potentially viremic cases in areas where the mosquito is present to prevent a local transmission cycle. This involves the early detection of all cases.

In practice, at the start of the season, physicians and laboratories are made aware of the risk of arbovirus transmission and instructed to immediately report any dengue cases to the Regional Health Agency (ARS), which then initiates an epidemiological and entomological investigation. In addition, an automated system for transferring results from the Eurofins Biomnis, Cerba, Inovie, and Biogroup laboratories makes it possible to “catch up” on cases that might not have been reported.

The detection of a biologically confirmed locally acquired case triggers an alert that prompts immediate action by the ARS and mosquito control operators. Santé publique France and the General Directorate of Health (DGS) are notified without delay. A specific epidemiological investigation is conducted, along with an entomological investigation and appropriate vector control measures. These are accompanied by communications to healthcare professionals, the public, travelers, and the relevant local authorities.

Case Definition

• Suspected case of dengue: a case presenting with a sudden-onset fever >38.5°C and at least one of the following signs: myalgia, arthralgia, headache, low back pain, or retroorbital pain, with no other apparent source of infection
• Probable case of dengue: clinical signs suggestive of dengue AND positive IgM serology
• Confirmed case of dengue: clinical signs suggestive of dengue AND positive RT-PCR OR positive NS1 test OR seroconversion OR a fourfold increase in IgG levels between two samples taken at different times
• Imported case of dengue: a case in which the patient has traveled to an area where the virus is known to circulate within 15 days prior to the onset of symptoms

Measures to Prevent Dengue Fever

As part of its prevention efforts, Santé publique France:

• Studies knowledge and prevention behaviors regarding arboviral diseases in mainland France to identify strategies for improving vector control
• Provides healthcare professionals and local authorities with a brochure dedicated to the prevention of dengue and chikungunya in metropolitan France
• Provides the general public with posters and digital ads to promote the prevention of arboviral diseases among travelers. The agency can also produce emergency response tools in the event of an epidemic.

These documents are available in the “Tools” tab.