Headlines - Chikungunya and dengue are reportable diseases

Chikungunya and dengue are arboviral diseases characterized by:

• incubation periods range from 1 to 12 days for chikungunya and from 3 to 15 days for dengue. The locations visited during this period help determine whether the case is locally acquired or imported from an endemic area

• viremia (presence of the virus in the blood) after the onset of symptoms lasts 5 to 7 days for both diseases. A vector insect that bites during this period can then infect another person through another bite

• The reservoir is human in mainland France, and transmission can only occur after a bite from an infected person during the viremia period

• Transmission is exclusively vector-borne (no direct human-to-human transmission). In mainland France, the only vector capable of transmitting these two diseases is Aedes albopictus. Therefore, no preventive measures need to be implemented in areas where the mosquito is not established (level 0)

• The disease originates in warm countries where there is an animal reservoir and several vectors, including Aedes albopictus, which has established itself in new areas such as the Mediterranean coast of mainland France

Aedes albopictus does not travel far on its own. Its geographic spread occurs through passive transport via human transportation modes (cars, trucks, trains, ships, airplanes, etc.). Internationally, entry points will therefore be highway rest areas, rail-road intermodal terminals, ports and airports, and markets of national importance. Spread is easier at the national level starting from the Mediterranean region, as the vector adapts more easily during short-distance movements with less extreme climatic contrasts. It is currently moving northward, where it is found sporadically (level 0b), including in Saône-et-Loire at a highway rest area in 2011 (but not yet in the rest of Burgundy and Franche-Comté).

It is therefore important to continue entomological and epidemiological surveillance. In the presence of suspected cases of chikungunya or dengue, the case must first be biologically confirmed (CNR for arboviruses), then the mandatory report must be filed with the ARS, which forwards it to the InVS, which determines whether the case is autochthonous or not. Entomological surveillance is important for detecting a potential shift from sporadic presence to established populations of Aedes albopictus in Saône-et-Loire and a possible northward spread.

Furthermore, bites from insects, arthropods, or plants are common and account for a significant number of emergency room visits during the summer months.