Tiger mosquitoes: new case of native dengue fever confirmed in France

A case of native dengue fever has been declared in Haute-Garonne in the south of France, meaning that the patient had not travelled to an at-risk country before being infected.

The case was confirmed today (Friday, September 2) in the commune of La Salvetat Saint Gilles, following a diagnosis by the Agence Régionale de Santé (ARS) Occitanie.

The virus is typically spread by tiger mosquitoes in countries that are known hotspots for the illness but this case has been declared without the patient having travelled to one of these areas.

It means it is considered ‘native’ or ‘indigenous’ and has come from within France itself. The virus must have been spread from another person who was infected and came to France having recently travelled to an affected country.

That person must then have been bitten by a healthy tiger mosquito, which went on to spread the virus to this new patient.

The patient’s health condition is not considered to be dangerous and they have symptoms similar to those of the flu.

It comes after another native case was reported in Occitanie late last month, this time in Hautes-Pyrénées.

Read more:New dengue fever case in France, victim had not travelled to risk area

Dengue fever is not normally considered to be present in mainland France. Each detected case requires obligatory reporting to health authorities and leads to an investigation led by teams at the relevant ARS and health body Santé Publique France (SPF).

This is so that prevention operations and checks can be put in place in the affected area as well as on the affected person and their local environment.

An operation to control tiger mosquitoes is now underway in the town. Residents will be informed by ARS and SPF officers and a health inquiry will be conducted door-to-door.

Any visitors or residents in the area who later present with dengue fever-like symptoms should let a doctor know immediately and inform them of their connection with the area.

Symptoms include:

• Sudden fever of at least 38.5C
• Headache
• Muscle, joint or bone pain
• Pain behind the eyes
• Nausea or stomach pain
• Rash
• Bleeding from the nose or gums
• Feeling tired, restless or irritable

Dengue does not cause a cough, running nose, or breathing difficulties. The presence of these symptoms as well as the others may indicate another illness but it is likely not dengue.

Similarly, symptoms of dengue can occur and can be a sign of serious illness, even if there is no fever.

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