Identification of a novel bluetongue virus vector species of Culicoides in Sicily.

The vectors of bluetongue virus are certain species of Culicoides biting midges, and in the Mediterranean area Culicoides imicola has long been considered to be the only field vector. In Sicily an entomological and serological surveillance programme has been in operation since the autumn of 2000, which has shown that the prevalence and abundance of C. imicola is lower than in many other Italian regions. Moreover, in 2002, there were outbreaks of bluetongue in the absence of C. imicola, and in these regions bluetongue viral RNA was detected by means of a nested reverse-transcriptase PCR in wild-caught, non-blood-engorged, parous Culicoides pulicaris. Furthermore, bluetongue virus serotype 2 was isolated on five occasions from extracts of non-blood-engorged parous C. pulicaris by using embryonated hens eggs and BHK-21 cells as assay systems. These findings suggest that in parts of Italy and possibly in other areas of Europe, where C. imicola is absent or rare, C. pulicaris may act as a fully competent vector of bluetongue virus.