Chikungunya: an unexpected emergence in Europe

International audience; Since the first outbreak of chikungunya in Italy in 2007, Europe has been facing an increase in local transmission of arboviral diseases. Dengue virus (DENV) and chikungunya virus (CHIKV) are both transmitted by the mosquito Aedes albopictus present in 20 European countries. CHIKV emergence in Europe was mainly associated with the East-Central-South African (ECSA) genotype, recently exemplified by the 11 CHIKV cases in southern France in 2014. Despite hundreds of travelers returning from the Americas where the Asian CHIKV genotype was responsible for more than one million cases, no autochthonous transmission associated with the Asian genotype was reported in Europe. Thus the pattern of transmission can be significantly different depending on the mosquito population, the virus genotype and environmental factors such as temperature.