A new strain of bluetongue virus, BTV 3, is currently spreading rapidly in the Netherlands and Northern Europe. Clinical signs of this new strain show that it is a much more potent serotype than previous strains; with mortality in sheep as high as 30-50% depending on the location and variant.
Whilst there are currently no reported cases of BTV 3 in the UK, the rapid spread of this disease is a cause for concern due to the proximity of recent outbreaks to the UK.
Disease surveillance programmes in the UK continue to monitor wind and model for the potential scenario of infected plumes of midges being blown across to mainland Britain.
Symptoms of BTV-3 can vary across ruminants, with clinical signs in sheep generally being more overt than in cattle. In sheep, clinical signs include ulcers in the mouth, discharge of mucus, drooling from the mouth and nose, oedema (swelling of the mouth, head and neck) and sudden death.
Reports in cattle suggest that they are less severely infected. Symptoms include mouth ulcers, nasal discharge, crusty erosions around the nostrils, lethargy and milk drop.
Calves can become infected with bluetongue virus before birth, if the mother is infected while pregnant. Signs of infection include calves born small, weak, deformed or blind, death of calves within a few days of birth and abortions
Bluetongue is a notifiable disease and it is important to get to know the clinical signs of BTV in order to allow for quick notification of suspect cases.
There is currently no vaccine against BTV 3. The current strategy centres around quick reporting and heightened surveillance for the disease. For other Bluetongue virus stains (1, 2, 4 and 8) vaccination remains the most effective way to protect a herd or flock. Should BTV 8 disease be detected in England, FUW members should consider vaccinating their susceptible animals.
Members should also discuss the risks of importing stock from BTV affected countries with their vet. Farmers should also take particular care when importing germinal products and should make sure that they know where the animals or donors originated from and that they meet all the export health certificate requirements. Requesting a pre-export test should be considered.
At present, the FUW is keeping a watching brief on this disease and will update members as the situation progresses.