Bluetongue virus – Latest situation: End of the seasonal low vector period

Bluetongue does not affect human health or food safety.

The UK’s Chief Veterinary Officer has urged farmers to remain vigilant for bluetongue virus after the disease was found in cattle and sheep in Kent, Norfolk and Suffolk.

The Animal and Plant Health Agency (APHA) and the Pirbright Institute identified the first case of the disease in November 2023 through Great Britain’s annual bluetongue surveillance programme. 

Current situation

We are out of the seasonal low vector period. This is because biting midge activity has increased with the warmer Spring weather. We are planning for a possible increase of bluetongue virus over the coming months as the weather warms and the risk of infected biting midges blowing over from northern Europe increases.

The risk of bluetongue transmission and therefore the risk level has not changed.

Farms close to the coast in counties along the east coast of England from Norfolk to Kent and along the south coast from Kent to Devon are at highest risk of incursion. 

Farmers should continue to monitor their animals frequently for clinical signs and make sure their animals and land are registered with APHA so we can locate animals in the event of an outbreak.

There is currently no evidence that there is circulating bluetongue virus.

Surveillance of susceptible animals and epidemiological assessments will continue. We will keep the situation under review.

Find out more information on the latest situation and guidance.

Bluetongue does not affect people or food safety. The virus is primarily transmitted by midge bites and affects cattle, goats, sheep and camelids such as llamas. The midges are most active between April and November and not all susceptible animals show immediate, or any, signs of contracting the virus. The impacts on susceptible animals can vary greatly – some show no clinical signs or effects at all while for others it can cause productivity issues such as reduced milk yield, while in the most severe cases can be fatal for infected animals.

The virus can also be spread through germplasm (semen, ova, and embryos) as well as transmitted from mother to unborn offspring. 

Strict rules on the movement of livestock from regions affected by bluetongue are already in place and farmers are reminded that animals imported from these regions must be accompanied by the relevant paperwork to clearly show they meet certain conditions designed to reduce disease risk, such as correct vaccination.

Following confirmation of BTV in a non-imported animal in England, some trading partners may restrict exports of bluetongue susceptible animals or their products. The latest information on availability of individual export health certificates can be found on Gov.uk.

NI and GB ruminants cannot be exported from an GB Assembly Centre to the European Union or moved to Northern Ireland until further notice.

BTV is a notifiable disease. Suspicion of BTV in animals in England must be reported to the Animal and Plant Health Agency on 03000 200 301 

More information about bluetongue is available here.

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NB: Current outbreak is in Northern Europe

Bluetongue is a notifiable disease of livestock in the UK, and as such if it is suspected it must be reported. This can be done by calling the Defra Rural Services Helpline on 03000 200 301. In Wales, contact 0300 303 8268. In Scotland, contact your local Field Services Office. It does not affect humans or food safety, but outbreaks can result in prolonged animal movement and trading restrictions.

Bluetongue was first described in South Africa but has been a recognised disease in most countries in the tropics and sub tropics for some time. Since 1999 there have been significant outbreaks in Greece, Italy, France, the Balearic Islands and for the past few years, cases have been springing up in northern European countries such as the Netherlands, Germany and Belgium.

Update 11 November 2023

Following routine bluetongue surveillance, a single cow has tested positive for bluetongue serotype 3 on a premises near Canterbury, Kent. A 10 km temporary control zone has been declared around the premises where the animal was kept. Movement restrictions apply to cattle, sheep and other ruminants.

Bluetongue affects sheep, cattle, other ruminants such as goats and camelids such as llamas.

Strains of bluetongue virus are currently circulating widely throughout Europe, and it is possible that bluetongue could spread into the UK if infected midges are carried by the wind to England. The exact level of risk depends on the proximity of disease in Europe and the weather conditions however bluetongue could also spread into the UK if infected animals, or germinal products, are imported from countries where bluetongue is circulating. Although the impact varies between strains (serotypes) and at present 24 distinct serotypes have been identified, Bluetongue can have significant economic impacts in terms of on farm losses due to death, sickness, reduced productivity and losses

The virus cannot be transmitted between animals - only via the bite of a Culicoide midge. However, the BVA concede that mechanical transmission is possible between herds and flocks, using contaminated surgical equipment or hypodermic needles. Animal keepers and vets should follow good practice when treating and vaccinating animals at risk of being infected with bluetongue.

Peak populations of vector Culicoides occur in late summer and autumn - resulting in a higher level of infection at that time. 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.

How to spot the disease

Clinical signs can vary by species, although symptoms are generally more severe in sheep. Cattle can be infected more frequently, but often show no symptoms at all and this is often the case for goats too.

If you keep livestock, you must continue to keep a close watch for, and report, any signs of bluetongue disease in your animals.

Signs of bluetongue in sheep include:

·        Eye and nasal discharges

·        Drooling due to ulceration of the mouth

·        High body temperature

·        Swelling of mouth, head, neck

·        Lameness

·        Haemorrhages

·        Inflammation of the junction of the skin and horn of foot - the coronary band

·        Respiratory problems

·        A blue tongue is rarely a clinical sign.

·        Deaths of sheep in a flock may reach 70%. Animals that survive may lose condition resulting in

·        reduction in meat and wool production

·        red skin as a result of blood collecting beneath the surface

In cattle
Cattle are the main carriers of bluetongue. It is possible that cattle will show no clinical signs but signs could include:

 

•         lethargy
•        crusty erosions around the nostrils and muzzle
•        redness of the mouth, eyes, nose
•        reddening of the skin above the hoof
•       nasal discharge
•        reddening and erosions on the teats
•       elevated temperature
•        milk drop
•         not eating
•        Swelling of the head, neck
•       Conjunctivitis
•         Swelling in and ulceration of the mouth
•        Swollen teats
•        Drooling

In cattle the disease cannot be diagnosed on clinical grounds and requires laboratory testing to confirm. Most adult animals show only mild clinical signs, or show no signs of disease at all.

In calves

Calves can become infected with bluetongue (BTV-8) 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

·        abortions

Livestock keepers and vets should consider bluetongue as a possible cause for calves showing these signs.

Preventing and controlling bluetongue

You can help to prevent the disease by:

·        vaccinating your cattle and sheep against bluetongue, in particular the BTV-4 and BTV-8 strains

·        having good biosecurity practices in place on your holding

What happens if bluetongue is suspected? 

·        If bluetongue is confirmed APHA will control the outbreak by following the contingency plan for notifiable diseases which can be found here and the bluetongue control strategy.

·        If there is an outbreak, then APHA will place movement restrictions in zones around the affected premises.

Vaccinating your animals

Vaccination is the best way to protect animals from the Bluetongue virus. You should discuss with your vet whether vaccination would benefit your business.

You will need to get a general licence to vaccinate animals if they’re outside a restricted zone for bluetongue.

It can take up to 6 weeks for your animals to be fully immune as your animals must have 2 injections of the vaccine, 3 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. 

To find out more

https://nadis.org.uk/disease-a-z/cattle/bluetongue-in-cattle-and-sheep/

Bluetongue: how to spot and report the disease - GOV.UK (www.gov.uk)

Photo Credit : Beth Driscoll