Simon Carpenter looks at the role of Culicoides species in the transmission of orbiviruses and, in the light of a paper summarised in this week's Veterinary Record, the particular implications regarding zoological collections

THE unprecedented emergence of bluetongue virus (BTV) in the north-western Palaearctic during 2006 led to a great deal of speculation regarding both the origin of the strain involved and the route by which it was carried into this region (Carpenter and others 2009). While initial suspicion naturally lay with those strains that were already circulating in southern Europe, this was swiftly dispelled by identification of the virus as a strain of serotype 8 (BTV-8), which had not been previously identified in the EU. Following this, phylogenetic analysis was able to reduce the likely area of origin to sub-Saharan Africa, although the limited number of strains available for comparison …