Update on Schmallenberg virus infections in small ruminants

In 2011 a new disease occurred in dairy cattle in the border region between the Netherlands and Germany, indicated by fever, reduction in milk yield and in some cases diarrhoea. The German Federal Research Institute for Animal Health detected a new orthobunya virus in blood samples of cows with fever, and named the virus for the localization of the infected cows, Schmallenberg virus. In the lambing season 2011/2012 numerous malformations occurred in lambs and kids in the Netherlands and in the northwestern parts of Germany, due to intra uterine infections of the foetuses mainly during the second month of pregnancy. The virus is transmitted by biting midges of several Culicoides spp. Subsequently the infection spread throughout the whole German country, and into several European countries including United Kingdom and Scandinavia. In contrary to cattle there are no clinical signs reported in adult small ruminants, but there are numerous malformations in newborn lambs mainly in form of the arthrogryposis-hydranencephaly syndrome.