Highlights from the Midi-Pyrénées Regional Health Agency - Dengue, Chikungunya, and Tiger Mosquito Surveillance in the Midi-Pyrénées Region

Dengue and chikungunya are two viral infections that are endemic and epidemic in tropical and subtropical regions. Dengue is the most widespread arbovirus disease in the world: mostly asymptomatic, it accounts for 1 to 5% of severe cases. Chikungunya, which primarily manifests as febrile arthralgia, is responsible for epidemics in Asia, Africa, and, since 2005, in the Indian Ocean. Both infections are transmitted by mosquitoes of the genus Aedes.

In metropolitan France, a temperate region, most observed cases are imported cases. However, the risk of transmission of these diseases is not zero due to the gradual establishment of the tiger mosquito Aedes albopictus in the country (the Provence-Alpes-Côte d’Azur, Corsica, and Languedoc-Roussillon regions). In fact, clusters of locally acquired cases occurred in 2010: two cases of chikungunya in Fréjus and two cases of dengue in Nice.

The presence of the tiger mosquito is subject to national surveillance, primarily in southern France. EID Méditerranée (Interdepartmental Agreement for Mosquito Control) conducts this surveillance for the PACA, Languedoc-Roussillon, and Midi-Pyrénées regions. In 2012, the mosquito was spotted in Lot-et-Garonne, and Aedes albopictus eggs were detected in Aveyron. However, it is not considered to be established in Midi-Pyrénées, and the region remains at Level 0 of the national plan against arboviruses.

Dengue and chikungunya are notifiable diseases (DO) in France and must be reported immediately to the ARS, for both autochthonous and imported cases. The DO applies to confirmed cases and aims to:

• monitoring imported cases in order to implement measures to prevent disease transmission around these cases,

• rapid detection of locally acquired cases in order to identify local transmission of the virus and guide vector control measures.