FAQs - Sheep Specific

Bluetongue causes fever (temperatures up to 40^oC), nasal discharge, swelling and ulceration of the mouth and tongue, runny eyes, depression, loss of appetite, drooling saliva, and swelling of the head and neck. Sometimes pregnant ewes can abort, and wool loss may be seen in animals which survive the infection. Death of infected sheep is common, often due to secondary bacterial infections.

There is no cure, but relieving the symptoms and nursing the sick animal means many sheep can survive the disease. Medications which are most likely to help are antibiotics and anti-inflammatories.Full recovery and regaining of lost condition can take several weeks.

All stock bitten by midges carrying the virus will be infected and a potential risk for transmitting disease, but not all will show clinical signs.

Yes, it affects all ruminants without immunity.

Via midges (Culicoides species), often referred to as the disease “vector”. Britain has 47 midge species – only a few of which transmit BTV. The female requires a blood meal to mature a batch of eggs. When she bites an infected animal, the virus multiplies inside her over a period of days (depending on the temperature). She then bites another animal and passes on the virus. Midges breed in wet leaf litter, mud, tree holes and stream banks.

Theoretically it may be possible to spread the virus on contaminated needles but the risk of this is extremely low and has never been identified in the field.

BTV can’t be contracted or spread through meat or milk and there is no sheep to sheep transmission. The key risk factors for British livestock are movements of live animals from infected areas and windborne midge movement.

No.

It is known that this has occurred in some cattle but less is known currently about sheep. Calves in this situation may be born infected but it is not clear as yet how important this is in disease transmission.

Because the vector is an insect, there are no guaranteed methods to prevent transmission of the disease. Control by avoiding or removing midge breeding grounds may reduce vector numbers, and Defra and SEERAD advise keeping stock away from low-lying damp grazing, particularly at dawn and dusk. Dung heaps or slurry pits should be covered or removed, and their perimeters (where most larvae are found) regularly scraped. Some insecticides can have an effect on midge numbers, but licensed options for use on sheep are limited. Preventing all midge bites is virtually impossible, so vaccination is the key method that can prevent disease spread.

BTV is a notifiable disease and restricted zones around outbreaks are required and controlled by EU legislation. A 20km radius zone is put immediately around the infected holding, beyond that is another 80km Protection Zone (PZ), followed by a Surveillance Zone (SZ) of at least 50km. Within this 150km zone, there are movement restrictions on livestock, carcases, semen and embryos to prevent transporting the virus to different parts of the country.

Plan how you will get all stock in to vaccinate them and make sure that when you get the vaccine, you will be able to do the whole flock in one go. Also be aware of any certification or declaration you may require according to Defra rules should you want to move your animals outside the PZ. To reduce the risk of disease in the meantime, vector control as per question 9 should be considered. As the vaccine is not licensed for use at the same time as any other products, it is worth planning the timing of other necessary vaccinations and treatments accordingly.