Many of your readers may be aware of the numerous confirmed cases of animals infected with bluetongue virus serotype 3 (BTV-3) in England (over 120 individual animals, first detected on November 10, 2023).

These cases were initially detected by annual risk-based surveillance surveys of farms in high-risk counties along the south and east coast of England, in conjunction with surveillance of imported animals and any suspect clinical cases.

Following this, the Scottish Government commissioned work to identify animal movements into Scotland from the affected areas in England. There were only a few tracings and all tested negative.

BTV is a notifiable disease affecting ruminants (such as sheep, cattle, goats, deer) and camelids (such as alpacas, llamas).

It is most commonly spread to livestock by midge bites, but BTV can also spread through the import or movement of infected animals, their germinal products (semen and ova), embryos and foetuses.

In sheep, symptoms include ulcers or sores in the mouth and nose, discharge from the eyes or nose, drooling and swelling of the lips, tongue, head and neck, and the coronary band (where the skin of the leg meets the horn of the foot).

Cows may display fever, lethargy, nasal discharge and redness of the mouth, eyes, nose, skin above the hoof, and teats.

If you suspect signs of any notifiable diseases, you must immediately notify your Animal and Plant Health Agency (APHA), which can be found on the Scottish Government website.

The first report of BTV-3 was in the Netherlands in September 2023, and has since been found in other Northern European countries. The most likely cause of the current 2023/24 cases in England are midges infected with BTV-3 blown across from continental Europe.

There is no evidence that the virus has circulated in the UK midge population. There is currently no vaccine for BTV-3. Vaccines are produced to protect against other strains (e.g. BTV-4 and BTV-8), but these do not protect against BTV-3.

BTV does not affect people or food safety. Meat and milk from infected animals is safe to eat and drink.

However, BTV can be serious in ruminant livestock and is a risk to the agricultural sector.

We should all remain vigilant for clinical signs of BTV, and contact your private vet if concerned. So far, BTV-3 has not yet shown clinical signs in livestock in England (unlike the rest of Europe). However, this could be due to the very late incursion of disease, low temperatures over the winter, and limited vectors (active midges) to spread disease.

BTV requires a minimum average temperature of 12°C to 15°C to replicate in midges. Therefore, environmental temperatures need to be consistently higher than this for infected Culicoides to become infectious and transmit the virus.

Due to BTV-3 cases in England, Great Britain as a whole has lost its disease-free status. Therefore, trade in live ruminant animals to the EU and movements to Northern Ireland are currently suspended.

The duration of this suspension is dependent on several factors, including a vaccine becoming available, regionalisation of parts of GB being pursued and approved by trading partners, or regaining disease freedom, which can take at least two years.

Take suitable precautions, outlined in Scottish Government guidance, or speak to your private vet before buying livestock or taking animals to any animal gatherings (e.g. shows, sales, markets etc.) in affected areas.

Source animals and germinal products responsibly and be aware of the disease risks.

If exporting germinal products outwith Great Britain, ensure you meet the Export Health Certificate (EHC) requirements and any additional assurance measures (such as testing donor animals before and after collection of semen before it is released for use).