Bluetongue Virus: Spread, Symptoms, Prevention, and Control

Kent is currently in a bluetongue-restricted zone extended in September 2024 to cover the entire county due to rising cases. Bluetongue is a notifiable disease caused by the bluetongue virus (BTV), which can have severe consequences for livestock keepers. Primarily spread by infected biting midges, the virus affects sheep, cattle,  other ruminants like goats and deer, and camelids such as llamas and alpacas. Though rare, it can also impact dogs and other carnivores if they consume infected material. While the virus doesn’t affect humans or food safety, outbreaks can lead to significant animal movement and trade restrictions.

How Bluetongue is Spread

Bluetongue virus can spread in several ways:

• Biting midges (Culicoides species) are the most common method of transmission. Infected midges bite animals, spreading the virus.
• Movement of infected animals or animal products (such as blood or germinal products like semen and embryos) can happen within the UK or via imports.
• Pregnant animals: Infected mothers can pass the virus to their offspring in the womb.

Biting midges found throughout Great Britain can also be blown over long distances by the wind, potentially bringing the virus from mainland Europe. The spread of bluetongue is influenced by factors like the time of year (midges are most active from April to November), weather conditions, and farm density.

Signs of Bluetongue

Livestock keepers must recognise the symptoms of bluetongue and report any suspicion immediately. Symptoms vary depending on the species and can be more severe in sheep.

In Sheep:

• Ulcers in the mouth or nose
• Swelling of lips, tongue, and head
• Fever, lameness, and breathing problems
• Red skin, discharge from eyes or nose
• Abortion or stillbirths

In Cattle:

• Redness and lesions around the nose, mouth, and teats
• Lethargy, fever, nasal discharge, and reduced milk production
• Calves may be born small, weak, or blind

In both species, pregnant animals may give birth to stillborn or deformed offspring if infected during pregnancy.

Preventing Bluetongue

There are several strategies to reduce the risk of bluetongue spreading:

1. Source livestock responsibly: Ensure animals come from disease-free environments.
2. Vaccination: Using authorised vaccines specific to the serotype can help reduce clinical signs, though they do not prevent infection.
3. Biosecurity measures: Maintain good hygiene on your premises and house animals indoors during high-risk periods, particularly at dawn and dusk when midges are most active.
4. Protect pets from potentially infected materials, such as aborted or afterbirth.

Vaccination and Licencing

Vaccinating animals is one of the most effective measures in controlling bluetongue. However, vaccination should be done under the appropriate licence depending on the serotype of the virus:

• Serotypes 1, 2, 4, and 8 have general vaccination licences.
• Serotype 3 (BTV-3) requires a separate licence.

Consult with your vet to determine whether vaccination is necessary for your animals and ensure that you comply with all licence conditions.

Reporting and Controlling an Outbreak

Bluetongue is a notifiable disease, meaning that any suspicion must be reported to authorities immediately. Failure to do so is a legal offence.

In England, report to 03000 200 301,

Wales to 03003 038 268, and contact your local Field Services Office in Scotland.

Refer to the Bluetongue Control Strategy and Bluetongue Regulations for detailed guidance on managing an outbreak, including movement restrictions and government-led control measures.