Bluetongue, an insidious viral disease affecting ruminants, has crept into the consciousness of UK livestock owners and veterinary professionals alike. Known primarily for its devastating impact on sheep, the disease also spares little comfort for cattle, goats, and other ruminants. With a heavy hand on both animal health and economic welfare, Bluetongue poses a threat that cannot be ignored, particularly in the face of shifting climates and increased global movement of livestock.
Bluetongue is caused by the Bluetongue virus (BTV), a member of the Orbivirus genus, and is primarily spread through the bite of infected midges (Culicoides species). This disease is not spread by direct contact between animals, making it a unique vector-borne challenge in the realm of livestock health. It may be spread by the movement of infected animals and animal products such as blood, semen, eggs, ova and embryos either within the UK or from outside through imports. Historically, Bluetongue had been confined to warmer climates, but changing weather patterns have allowed its vector to migrate northward, bringing it to the UK’s doorstep, infiltrating primarily the SE area of England but now spreading further afield.
The first major incursion into the UK happened in 2007, and although the virus itself has not yet claimed its place as a persistent issue in the UK, it looms as a recurring threat, especially given the proximity of outbreaks in France, Belgium, and Germany continuing to raise concerns. At the time of writing, a further 133 cases have just been confirmed within the restriction zone and a further 11 cases, including 2 cases in Wales were linked to moves from high-risk areas.
DEFRA and the VMD have approved the use of 3 non-UK veterinary medicines, which can now be used in England in or out with the restriction zone. Livestock keepers in Scotland and Wales can apply to the APHA for a specific licence to use these vaccines. Call or email our customer enquiries team on 01387 262626 / enquiries@covetrus.com
Clinical Picture and Consequences
Sheep are more likely to show obvious clinical signs of bluetongue than cattle if they become infected with the virus. Signs of bluetongue in sheep include:-
- Fever and general malaise.
- Swelling of the lips tongue, head and neck (sometimes a blue discoloration of the tongue, hence the name).
- Lameness, caused by inflammation of the coronary band.
- Mouth ulcers and nasal discharge, resulting in severe discomfort and difficulty eating.
In contrast, cattle often serve as silent carriers of the virus, showing far milder signs such as slight fever or lameness. While they may not always display the dramatic symptoms seen in sheep, cattle act as reservoirs, contributing to the continued circulation of the virus in the environment and are often the preferred host for biting midges.
The economic damage caused by Bluetongue can be immense, beyond the loss of productivity or animal welfare concerns. Restrictions on animal movement, essential in controlling the disease, can severely disrupt trade, affecting livestock sales, breeding, and farming operations across the board.
An Ongoing Threat
Veterinary professionals are acutely aware of the importance of remaining vigilant. The UK’s last brush with Bluetongue was curtailed thanks to a coordinated vaccination effort, which targeted the BTV-8 strain responsible for the 2007 outbreak.
Vaccination remains a cornerstone in protecting livestock from Bluetongue. However, it requires a targeted approach, as different BTV serotypes circulate in different regions. Vaccines must match the specific strain posing a threat, something that adds complexity to prevention efforts.
The current strain BTV-3 is a relatively new strain, first reported in September 2023 in the Netherlands. Cases have since been reported in Belgium, Germany, France, Luxembourg, Denmark and Switzerland. The first case was confirmed in the UK on 10 November 2023.
Beyond vaccines, biosecurity measures are essential to safeguard the UK’s livestock. Collaboration with farmers is vital and educating livestock owners on early detection, symptom recognition, and the importance of immediate reporting is key to limiting the impact of any potential outbreaks. They need to understand how best to prevent midges from establishing breeding grounds, such as by eliminating standing water and using insecticides when necessary. Additionally, import controls and regular health checks on incoming animals from high-risk areas form the front line of defence against future outbreaks. Further, ongoing communication with regulatory bodies ensures that any sign of the disease is quickly addressed, preventing it from spreading unchecked.
Staying One Step Ahead
Bluetongue is not a battle fought once and won. It is an ever-present threat that demands preparedness from the entire veterinary and farming community. In the face of changing climates and global trade, the UK’s livestock is at risk of future incursions. But through continuous vigilance, proactive vaccination strategies, and tight biosecurity measures, the veterinary profession can work to shield the industry from the destructive path of this virus.
Veterinary surgeons must remain at the forefront of this effort, leading the charge in surveillance, prevention, and education and we want to do everything we can to support them. Together with farmers, regulators, and researchers, we can ensure that the UK’s livestock remains resilient against the threat of Bluetongue.
By Ruth Hastings
BVMS MRCVS Reg: 6162769