Case of autochthonous dengue fever near Toulouse: “We must act quickly to contain the contamination”

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A dengue outbreak has been identified in La Salvetat-Saint-Gilles in people who have not travelled. A mosquito control took place this weekend. This is the third focus of autochthonous dengue fever identified since July by the Regional Health Agency (ARS Occitanie), which explains this phenomenon and the means to contain it.

Why can we catch dengue without traveling to the tropics as was the case for six people this summer in Midi-Pyrénées? Should we be worried about it? How to protect yourself? Update with Isabelle Moussion, regional vector control coordinator at ARS Occitanie.

Several cases of dengue fever among people who have not traveled abroad have been identified this summer in Occitania, what about?

This infectious disease, usually absent from France and transmitted by the bites of tiger mosquitoes, is most often contracted by patients who have stayed in tropical areas. We are talking about imported cases and not reporting them to the public. This time it’s different. Since July, we have identified three indigenous outbreaks, that is to say patients infected without having stayed abroad. The first in the Pyrénées-Orientales is extinct, the second in the Hautes-Pyrénées (in Andrest) is still active, the last to date appeared in Haute-Garonne at the Salvetat Saint-Gilles. This concerns six patients.

“The mosquito that has taken on the virus becomes a contaminate for all future bites”

How is it possible ?

There is talk of an autochthonous chain of transmission when a patient who has not traveled (in the 15 days preceding the symptoms), contracts the virus. This occurs because an imported case was not detected upstream. The autochthonous chain of transmission, is done by a mosquito, healthy at the start but which is loaded with virus after having bitten a person returned to France. The mosquito then becomes a contaminant for all future bites, knowing that it has an average lifespan of one month, this can go very quickly.

Is this phenomenon new?

The tiger mosquito was first spotted in Occitania in 2011-2012 and autochthonous cases had already been reported in Hérault and Gard. But this is a first for the west of Occitania. Fortunately, so far we have managed to contain the outbreaks, but we insist on prevention.

How to protect yourself?

The difficulty is that 50% of patients are asymptomatic. Thus, returning from endemic areas, we recommend protecting yourself from mosquitoes with approved repellents for 7 days; to consult your doctor in case of symptoms (fever above 38.5°, headaches, body aches, retro orbital pain). A biological analysis makes it possible to remove the doubt and in the event of illness, the information goes back to the ARS. We then expedite the health survey and treat the area concerned.

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