Rising cases of bluetongue virus in Europe have prompted the UK’s chief vet to renew warnings to livestock farmers in high-risk areas of eastern England.
The potentially-fatal animal disease was found in dozens of cattle and sheep in Norfolk and Suffolk last winter.
Temporary restrictions on animal movements were lifted in February as the colder weather lessened the activity of biting midges which carry the disease - but the risk of a new incursion has risen in the warmer summer weather.
The latest outbreak assessment from the Animal and Plant Health Agency (APHA) confirms growing outbreaks of the BTV-3 virus strain in the Netherlands, Germany and Belgium, with more than 4,000 recorded new cases reported since May 2024.
The first cases have also been confirmed in France, Luxembourg and Denmark, while the virus strain has "successfully overwintered in the Netherlands, Germany and Belgium".
While the overall risk level for an incursion of BTV-3 into Great Britain remains at "medium", the risk of infected midges being blown over from northern Europe depends on weather conditions - and they are generally more active during the warmer months.
Defra warned farmers "should therefore continue to monitor their animals frequently for clinical signs and are reminded of the vital importance of responsible sourcing of animals with a reliable health status".
Free testing is also available for animals moving from the highest-risk coastal counties of Norfolk, Suffolk, Essex, Kent and East Sussex, to help guard against transporting undetected disease to new areas.
Chief veterinary officer Christine Middlemiss said: "BTV outbreaks in Europe are on the rise and we must remain vigilant to the threat of disease spread. If you suspect disease in your animals please report.
"If you intend to move animals to live out of high-risk counties, including if you are buying in new animals, please take advantage of the free testing scheme to help stop the movement of non-clinical disease.
"Bluetongue does not pose a threat to human health or food safety, but the disease can impact livestock farms, and damage animal and business productivity."
Bluetongue virus affects ruminant animals including cattle, sheep and goats, and also camelids such as llamas. It is a notifiable disease, and suspected cases must be reported to the APHA on 03000 200 301.
For more information on disease prevention and animal testing, see www.gov.uk/bluetongue.
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