Schmallenberg virus (SBV) infects domestic animals such as cattle, sheep and goats, but has also been found in bison, moose, alpacas, buffalos and deer. It was first isolated in 2011, and identified as a novel virus from the Bunyaviridae family, genus Orthobunyavirus. As of 2015, there are 18 serogroups within the genus, of which SBV is a member of the Simbu serogroup. It is an enveloped virus with a capsid and single stranded RNA genome.
SBV causes Schmallenberg disease and preferentially infects the central nervous system of cattle and sheep. Clinical signs can vary between species; recovery can occur within a few days or there may be no symptoms at all in adult cattle. However, severe birth defects can be seen if females are infected during pregnancy.
- Reduced milk production
- Birth defects (depending on stage of gestation):
- Premature birth or stillbirth
- Birth of mummified foetuses
- Malformations of the brain, skull, neck, spine and joints
SBV is spread primarily by midges of the Culioides species. It can also be transmitted during pregnancy, and although the virus has been found in semen it has yet to be shown that this could be a source of infection.
Previously viruses from the Simbu serogroup had never been isolated in Europe before 2011. SBV was first detected in November 2011 in Schmallenberg, Germany and up to now, the Netherlands, Belgium, Germany, United Kingdom, France, Luxembourg, Spain, Italy, Switzerland, Austria and Ireland have reported stillbirth and congenital malformations as a result of infection.
Impact for Society – what are we doing?
The Institute is currently researching the ways that the midges are able to spread SBV. This involves studying both the virus and the vectors and using mathematical modelling to predict the spread of the vectors and disease. Diagnostic testing is also being worked on and together all these factors will enable the Institute’s experts to tailor advice to a wide range of stakeholders, including livestock owners. This work will also inform us whether there are suitable control methods that might lessen the impact of the disease.