Risk of introduction of alphaviruses responsible for American equine encephalitides in Belgium

Arthropod-borne viruses are a threat for human and animal healths in regards with their dissemination out of their endemic area. The arboviruses reviewed here belong to the family Togaviridae genus Alphavirus and are small enveloped positive sense RNA viruses. They are considered as exotic equid pathogens in Europe and can cause severe diseases in humans in the context of an epidemic. Arboviruses have complex epidemiologic features characterised by interactions between viruses, vectors, reservoir or susceptible host species, and environment. A bibliographic search was performed to identify the mean factors that influenced past outbreaks in America and the presence of potential vectors/vertebrate hosts that could play a role in the transmission cycle in Belgium. Three equine arboviruses, currently considered as the main current threats of emergence/introduction in Western Europe, were chosen as model for this study: Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV) and Venezuelan equine encephalitis virus (VEEV). In conclusion, taking into consideration the globalisation (increase of international exchanges) and climate warming, the analysis of the different features of the arbovirus cycles are essential to a balanced risk expertise in the Belgian context. Research supported by the Belgium Federal Public Service, Health, Food Chain Safety and Environment.INDEVIREQ 1.