- 29 Oct 2018
Bluetongue is a notifiable insect-borne viral disease that affects sheep, cattle, other ruminants such as goats and camelids such as IIasmas. It cannot be spread directly between animals and relies on the midge as a vector for transmission.
It does not affected people or food safety, but outbreaks can result in prolonged animal movement and trade restrictions.
The last outbreak in England, Scotland or Wales was in 2007.
Animal keepers should be very vigilant for any signs of notifiable disease and report any suspected cases to APHA immediately. When importing animals into Scotland, animal keepers should ensure they consider the risks carefully and check the health status of the animals. Animal keepers should also consult their vet on other measures, such as protective vaccination.
You should discuss the risks of importing stock from BTV affected countries with your vet.
Infection with bluetongue can significantly compromise livestock welfare, both in terms of unpleasant symptoms and a potentially high mortality rate (around 30%).
Animals can recover from the disease. Such animals become immune to the strain with which they were infected and, after around 60 days, they stop shedding virus into the bloodstream, meaning that they no longer pose a risk in terms of onward infection of the midge population. However, there are long terms impacts on productivity and fertility.
The clinical signs are more apparent in sheep, than other ruminants, and can include:
- swelling of the head and neck
- inflammation and ulceration of the mucous membrane of the mouth, nose and eyelids
- loss of muscle tone and weakness
- haemorrhages in the skin and other tissues
- respiratory signs such as froth in the lungs and an inability to swallow and discolouration; swelling of the tongue.
Although bluetongue usually causes no apparent illness in cattle or goats, cattle may display clinical signs including:
- nasal discharge
- swelling and ulceration of the mouth
- swollen teats
How bluetongue is spread
Midges carry the bluetongue virus. They are infected with the virus when they bite an infected animal. The virus spreads when the infected midge bites an uninfected animal. Once a midge has picked up the BTV virus it will be a carrier for the rest of its life.
The midge season in the UK is usually April to November. The weather, especially temperature and wind direction, affects how quickly, and how far midges can spread the disease.
Human health implications
The disease does not affect humans.
How to control the disease
The measures to control and eradicate the disease include vector control, (use of insecticides in the animal premises and in the areas where these insects live, insect repellents onto animals, mosquitoes nets, etc.), restriction to movements of live ruminants from affected areas to non-infected regions where the vector is present and the use of vaccines.
If bluetongue is confirmed APHA will control the outbreak by following the contingency framework for exotic notifiable diseases and the bluetongue control strategy.
Guidance on the import of animals from bluetongue affected countries and movement restrictions during an outbreak is available on gov.uk.
Vaccination is the best way to protect animals from the bluetongue virus. You should discuss with your vet whether vaccination would benefit your business.
It can take up to six weeks for your animals to be fully immune as your animals must have two injections of the vaccine, three weeks apart.
Vets can apply to the Veterinary Medicines Directorate for a Special Import Certificate (SIC).
The certificate allows keepers to import safe and effective bluetongue vaccine directly from the EU to vaccinate their stock.
It is important to practice good hygiene when vaccinating animals as bluetongue can also be transmitted through dirty needles.
Powers for the control of bluetongue are laid out in:
- the European Commission Directive 2000/75/EC as amended, laying down specific provisions for the control and eradication of bluetongue
- the Commission Regulation (EC) No. 1266/2007 as amended, on protection and surveillance zones in relation to bluetongue and conditions applying to movements from or through these zones (updated as new outbreaks occur and as new information on control methods arises)
- the Bluetongue (Scotland) Order 2012, lays out how European rules on bluetongue are implemented in Scotland
- the following Declaration is made under The Bluetongue (Scotland) Order 2012: Declaration of area in which voluntary vaccination against bluetongue is permitted
Biosecurity is about being aware of the ways disease can spread and taking every practical measure to minimise the risk of disease spreading. The advice details practical things you can do on your farm to help prevent the introduction and spread of bluetongue to and from your animals.
If you suspect signs of any notifiable diseases, you must immediately notify your Scotland: field service local office at the Animal and Plant Health Agency (APHA). Failure to do so is an offence.