Schmallenberg virus gets its name from the German, Winterberg, where the virus was first identified in cattle in November 2011. After testing ruled out various other illnesses, the orthobunyavirus (Schmallenberg virus) was identified by metagenomic analysis and virus isolation of infected cattle in Germany.
The Schmallenberg virus is related to the Simbu serogroup viruses, in particular Shamonda, Akabane, and Aino virus.
So far, research confirms that the virus is vector-borne, spread by insects, mainly flies/ midges.
The virus affects cattle, bison, sheep and goats. To date (February 2011), the disease has mostly been recognised in small ruminants around the time of partuition, with offspring showing signs of brain damage or malformations.
There is no risk to human health, says the OIE.
Clinical symptoms
Manifestation of clinical signs varies by species: bovine adults have shown a mild form of acute disease during the vector season, congenital malformations have affected more species of ruminants (to date: cattle, sheep, goat and bison). Some dairy sheep farms have also reported diarrhoea.
Adults (cattle)
- Probably often inapparent, but some acute disease during the vector-active season
- Fever
- Impaired general condition
- Anorexia
- Reduced milk yield (by up to 50%)
- Diarrhoea
- Recovery within a few days for the individuals, 2-3 weeks at the herd scale
Malformed animals and stillbirths (calves, lambs, kids)
- Arthrogryposis (abnormal joints)
- Hydrocephaly (build up of fluid in skull)
- Brachygnathia inferior (overshot jaw)
- Ankylosis (stiff joints)
- Torticollis (twisted neck)
- Scoliosis (deformed spine)
As of yet there is no vaccine for the virus, which will take some times, perhaps up to two years, to develop. Farmers are urged to stay vigilant and report any suspected cases.