Schmallenberg virus detected by RT-PCR in Culicoides biting midges captured during the 2011 epidemic in The Netherlands #

Abstract

Infections with Schmallenberg virus (SBV) are associated with congenital malformations in ruminants. To identify potential vectors for SBV, Culicoides collected in the autumn of 2011 in the Netherlands were tested retrospectively by RT-PCR. A total of 610 pools of heads (10 Culicoides/pool) from 6,100 female Culicoides were analyzed. Twelve pools of the Obsoletus Complex and two pools of C. chiopterus tested positive, the majority with C t -values of between 20 and 30. Molecular sequencing of positive Obsoletus Complex midges revealed eleven to be C. scoticus and one C. obsoletus sensu stricto. Prevalence of SBV in midges of the Obsoletus Complex was 56 per 10,000, ten times higher when compared to bluetongue virus detection in the same Culicoides species in Europe during 2002-2008. Vector biology might have been positively influenced by climatological circumstances in 2011 with a prolonged vector season (several weeks) and a higher survival rate and increased vector abundance (rain in summer and higher temperatures