peer reviewed ; The emergence of Bluetongue, due to the virus of serotype 8 (BTV-8) was an unexpected event in Belgium. This vector-borne disease is caused by a virus belonging to the family of Reoviridae, genus Orbivirus whose genome consists of 10 double-stranded RNA segments. During this emergence, the virulence of the BTV-8 was exacerbated in bovines and was expressed by the appearance of severe clinical signs and reproductive disorders. The contribution of the Unit of research in epidemiology and risk analysis applied to veterinary sciences (UREAR-U.Lg.) consisted of the description, the understanding and the analysis of the particular profile which was observed during this emergence. This understanding required both field studies and a series of experimental infections in high containment facilities. Overall, emergent animal diseases have been of particular importance these last few years and represent unprecedented health, socio-economic, international, biological, partnership and media challenges.