It’s been so interesting to keep up to date with the development of the Schmallenberg Virus (SBV) research. Developments have been rapid and since June 2013 a vaccine (Bovilis SBV) has been available to farmers in the UK. Here’s an outline of the information currently available regarding the virus:
In August and October 2011, regions of Netherlands and Germany experienced outbreaks of a disease in adult cattle that included:
- mild to moderate pyrexia (fever)
- loss of appetite
- reduced milk yield
- deterioration of body condition
Alarm bells rung when all tests for similar, known diseases came back as negative. After 5 days the animals had recovered.
From December 2011 farms in the Netherlands, Germany and Belgium experienced a higher percentage of abortions and stillbirths associated with foetal abnormalities, affecting mainly sheep. It was around this time that scientists identified and named the virus.
In early 2012, the first cases were suspected in the south and east of England. Deformed lambs were investigated and it was confirmed to be SBV. Since then, the disease has been diagnosed across a large area of Southern and central England in deformed lambs and calves. There have also been cases in Scotland and Ireland. It’s believed that the virus is spread by biting insects, in this case members of the midge family blown over to the UK from Europe.
When working on a local farm, I saw first-hand the effects of the virus. The lambs of infected mothers had slightly bent limbs and fixed, swollen joints. I was told that others were born with twisted necks and spines, brain deformities and damage to the spinal cord. Many of these were euthanized at birth as their quality of life would have been awful. The severity of the deformities varies depending on how far along in pregnancy the mother became infected. If infection occurs in the early stages the virus can cross the placenta and infect the foetus while its immune system is still developing, meaning it can’t fight it off. In many cases the mothers don’t display any signs of illness, making it near impossible for farmers to predict the impact of the virus on their livestock.
Animals infected with similar virusesexperience a strong immune response protecting them from a second infection of the virus, meaning they do not usually give birth to deformed offspring more than once. It is hoped and expected that SBV will provoke a similar response, but as the disease is so new, long term effects are not yet known. No human cases of infection have been detected in any country.
Further research needs to be done, DEFRA state that ‘UK institutes are working collaboratively with European organisations researching how the midges spread the virus, how the virus causes disease, duration of immunity, other routes of transmission, infection in other species and reservoirs of infection, and the role of semen and embryos in transmission. Possible effects on fertility and conception are also currently under investigation.’
A few of the roles of a vet regarding this virus seem to be:
- Giving advice on and administering the new vaccination
- Aiding the difficult births caused by the foetal abnormalities
- Making decisions on the euthanasia of calves/lambs with severe deformities
- Carrying out tests on herds