Schmallenberg virus (SBV) was first diagnosed in the UK early this year following tests carried out on deformed lambs.
Active infection has now been diagnosed on farms as far north as North Yorkshire. So far, one animal imported from Shropshire has tested positive for antibody to the virus in Orkney, showing that it had been infected on its farm of origin.
SBV affects cattle, sheep and goats and is transmitted by midges. Transmission occurs when a midge bites to feed on the blood of a ruminant.
Cattle acutely affected by SBV may develop signs such as a drop in milk yield, fever and diarrhoea. These signs are normally short lived and are not fatal.
Following infection, it is believed that animals become immune. Female animals that develop immunity before they become pregnant are unlikely to give birth to affected offspring. However the virus causes abortions and serious birth defects in calves and lambs when animals are infected for the first time when they are pregnant.
Animals are at most risk during the warmer months when midges are most active. There is likely to be at least another three weeks of midge activity left this year.
The SAC is keen for farmers to stay vigilant against any signs of SBV. Any suspicion of the virus, particularly in adult cattle at this time of year, should be raised with your vet and testing should be carried out for the virus if appropriate. Laboratory testing for any suspected cases is now subsidised as part of the SAC Veterinary Services and AHVLA enhanced surveillance scheme.
Any calves and lambs born with abnormalities may be submitted to the SAC for a Schmallenberg investigation.
Scottish farmers importing animals from SBV-risk areas elsewhere in the UK are urged to submit animals to the voluntary screening regime set up by the NFU-S, the Scottish Government and SAC Veterinary Services. Laboratory fees are free for up to four animals under this scheme.
Alwyn Ll Jones