Six autochthonous dengue fever transmission cases have been reported in France since early September, according to Public Health France (computer translated).
An indigenous transmission center of the dengue virus has been identified in Saint Laurent du Var (Alpes-Maritimes) since 4 October 2018. As of 19/10/2018, 5 cases have been identified.
An indigenous case of dengue fever has been confirmed in the department of Hérault (commune of Clapiers) .
These two episodes of autochthonous transmission are not epidemiologically linked and the viruses are of different serotypes.
The European Centre for Disease Prevention and Control (ECDC) offers the following details on the cases in a Rapid Risk Assessment:
On 4 October 2018, the laboratory of virology of Montpellier University Hospital and the French National Reference Laboratory for arboviruses in Marseille confirmed a case of dengue type 2 in Saint Laurent du Var, Alpes Maritimes department, Provence-Alpes-Côte d’Azur region, in southern France. The case, who had become symptomatic on 21 September, is a resident of Saint Laurent du Var and had no travel history outside the region in the 15 days prior to symptom onset and was assumed to have become infected locally. This was the first autochthonous case of dengue identified in metropolitan France in 2018. Door-to-door case finding conducted on 8–9 October 2018 lead to the diagnosis of four additional cases residing within a 50m-radius from the home of the index case. Onset of symptoms of the five cases detected in Saint-Laurent du Var ranged from 3 September to 3 October.
On 10 October 2018, the French National Reference Laboratory for arboviruses confirmed a case of dengue type 1 in Montpellier, Hérault department, Occitanie region, in southern France. The case, a resident of Le Clapiers, a suburb of the city of Montpellier, developed symptoms on 27 September 2018. The patient had no travel history outside the region in the 15 days prior to symptom onset. Montpellier is 270 km west of Saint Laurent du Var, where the cases described above occurred. There is no link between the cases in Montpellier and the ones in Saint Laurent du Var.
Epidemiological investigations have been set up to identify other possible cases and to strengthen prevention and surveillance measures. Health professionals in the two communes where the cases were identified were also made aware of the detection and reporting of other people with suspected dengue fever. Mosquito control operators immediately carried out entomological investigations and undertook targeted mosquito control activities. These actions are systematically accompanied by a prior information campaign for local residents.
Due to the identification of an outbreak of indigenous cases in the Alpes-Maritimes, the department was placed in level 3 of the anti-dissemination plan for chikungunya and dengue in mainland France .
With only one indigenous case identified to date in the Hérault, the department is still at level 2 of the anti-dissemination plan for chikungunya and dengue in mainland France .
Circulatory transmission of dengue has already occurred several times in 2010, 2013, 2014 and 2015 on the French Mediterranean rim affecting from 1 to 7 people.
Detection of further cases in the affected regions and elsewhere is possible. Ae. albopictus is normally active in the area of Saint Laurent du Var until the beginning of November, while in Montpellier the active period for Ae. albopictus can even last until early December.
Since May, France has also reported 154 imported cases of dengue fever.