Ovine Catarrhal Fever (Bluetongue): Analysis of Culicoides Species in Seropositive Farms

Abstract

Bluetongue (BT) is an orbiviral disease of wild and domestic ruminants, mainly sheep. In Sicily, the first Bluetongue outbreak occurred in October 2000; there have been 76 recorded outbreaks so far. The National Surveillance Plan, based on European Union Commission Decision 138/2001/CE, establishes serological and entomological surveys. This plan consists of controls of seronegative cattle, called 'sentry' as indicators for the presence and circulation of virus in defined areas. To check the seroconversions, the regional territory has been subdivided in 400 km(2) areas including 58 seronegative cattle, periodically checked by serological tests. All positive sera have been tested to detect the specific serotype by the National Reference Centre for Exotic Diseases (CESME) at the Istituto Zooprofilattico Sperimentale Abruzzo e Molise in Teramo (IZS Teramo). Moreover, entomological surveillance has been implemented in seropositive herds, to investigate the presence of insect vectors belonging to Culicoides genus. The goal of the present communication is to report on the different species of Culicoides found in the farms with Bluetongue virus and to investigate on the probable role of new competent vectors. This paper concerns data analysis of 581 light-trap catches collected in 321 farms from 2003 to 2008. We observed that 82% of checked farms were positive for Culicoides spp., and only 10% of the farms were positive for Culicoides imicola.