Schmallenberg Virus

In November 2011 a new virus was identified which had been causing problems in Germany and the Netherlands since August. This was named ‘Schmallenberg virus’ (SBV) after the German town where the virus was first identified.

Between August and October 2011, outbreaks of disease in adult cattle that included mild to moderate fever, reduced milk yield, loss of appetite, loss of body condition and diarrhoea were reported in both the Netherlands and Germany. Testing for common causes proved negative.From December 2011, abortion and stillbirths associated with foetal abnormalities, affecting mainly sheep but also cattle and goats, were identified in the Netherlands, Germany and Belgium.  At the begining of 2012 there were suspected cases in thr South and East parts of England. Deformed lamb were tested and the viral infection was confirmed to be the cause. Further cases occured in Southern and Central England later.

As yet, the disease has remained soley European with outbreaks in: Germany, Belgium, England, the Netherlands, Denmark, Spain and Italy. So far the disease has only affected goats, sheep and cattle. The disease is highly unlikely to be zoonotic (affecting humans), as so far no human cases have been detected and the viral strains clostest to the SBV all only affect animals.

Transmission

It is suspected that the disease is transmitted by biting insect vectors, such as midges and mosquitos but the exact mechanism of transmission is still unknown due to the recent nature of outbreaks. It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors originating in Europe.


Symptoms


-In adult animals: diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days. The infection tends to remain with the herd for 3-2 weeks.

-In Newborns and Foetuses: The second presentation of the disease is associated with abnormalities in animals born alive or dead at term or aborted following infection of the dam, affecting mainly sheep but also cattle and goats. Malformations observed to date include bent limbs and fixed joints (arthrogryposis), twisted neck or spine, a domed appearance to the skull, short lower jaw and brain deformities (spaces filled with fluid in cerebral hemispheres, abnormally small parts such as cerebellum and brainstem) and marked damage to the spinal cord.

Diagnosis/ Post mortem techniques

Histopathological: Microscopic examination of tissues in order to study disease manifestations.
Serological: The study of blood serum and other bodily fluids in order to test for disease.
Virological: The study of the infecting virus.
- Carcasses of abnormal lamb/calves should be sent to the VLA with a blood clot from the dam; this allows an indirect test for antibodies to be conducted.

Treatment

There is no treatment or vaccine currently available for this disease. As this is a new disease further work is needed to determine what control measures may be appropriate. 

Recent News:

A ram in Orkney recently tested positive for SBV after being moved there. The virus is reportedly moving North across britain,and it is vital that farmers maintain good biosecurity to prevent this relatively problematic virus from spreading further. Having isolated the virus, vaccinations are currently being developed in order to trigger the body to produce virus neautralizing antibodies, and the aim is to have a vaccine by the end of 2012.