Headlines - Chikungunya and Dengue: Risk of Outbreaks in Mainland France

Detected in Italy in the 1990s, Aedes albopictus (A. alb.), commonly known as the tiger mosquito and a vector for the dengue and chikungunya viruses, has gradually established itself since 2004 in 18 departments in southern France.

The plan to prevent the spread of chikungunya and dengue in mainland France aims to strengthen entomological and epidemiological surveillance, particularly in areas where A. alb. is established, to prevent and assess the risks of these two viruses spreading. Epidemiological surveillance in mainland France relies on mandatory reporting (MR) of biologically confirmed cases.

As a hyperendemic region for dengue, the French departments of the Americas (DFA) have been experiencing a chikungunya epidemic since December 2013, which is currently widespread in Martinique and Guadeloupe with nearly 100,000 clinical cases as of June 29, 2014. This situation increases the risk of these diseases emerging in mainland France due to the return of virus carriers (a risk confirmed by the detection of 2 autochthonous cases of chikungunya in 2010 and 3 autochthonous cases of dengue between 2010 and 2013 in the PACA region). The guide on the implementation procedures for the anti-spread plan was updated in April 2014, notably with the establishment of enhanced surveillance. It provides for:

• across the entire metropolitan territory, the reporting and DO of any confirmed case of chikungunya (or dengue); epidemiological investigation of confirmed cases allows for verification of their potential passage through areas infested by the vector during their viremic period;

• in metropolitan departments where the A. alb mosquito is established and during the vector’s expected activity period (May 1 to November 30), reporting and investigation of all suspected imported cases of chikungunya (or dengue), without waiting for the results of laboratory tests, to enable rapid intervention by vector control services (LAV) around potentially viremic cases to prevent possible virus transmission.

From May 1 to July 4, 2014, 350 suspected cases of dengue or chikungunya were reported in the six regions where surveillance is enhanced. Among these, 47 imported cases of dengue and 127 imported cases of chikungunya were confirmed, as well as three imported cases of co-infection. There were no locally acquired cases. Since May 1, four case reports of confirmed imported chikungunya cases and one of dengue have been received by the Burgundy Regional Health Agency (ARS), as well as two chikungunya case reports by the Franche-Comté Regional Health Agency (ARS).