Bulgaria reports new bluetongue outbreak as virus spreads across Europe

BULGARIA – Bulgaria has reported a new case of bluetongue disease in a southern sheep farm, marking the second confirmed outbreak in the country in just two weeks, according to a notice by the World Organisation for Animal Health (WOAH). 

The case was detected in the district of Devin, where one sheep in a flock of 323 tested positive for serotype-8 of the virus.

The confirmation adds to mounting concern across Europe as the bluetongue virus (BTV) spreads rapidly this summer. 

Earlier at the end of July, Bulgaria identified two cases of BTV-8 in a small backyard flock near its border with North Macedonia. Both incidents represent the first time this strain has been recorded in the country.

A widening European outbreak

Bluetongue, a viral disease transmitted by biting midges, affects domestic ruminants such as sheep, cattle, and goats.

Bluetongue is a notifiable viral disease, and by law, it must be reported to government authorities to allow them to monitor disease spread, detect outbreaks early, and implement control measures.

It can cause severe illness and death in livestock but does not pose any risk to humans or food safety.

According to the UK’s Department for Environment, Food and Rural Affairs (DEFRA), Europe is facing one of its most intense bluetongue seasons in years.

Its latest outbreak assessment, published on August 12, confirms the start of the 2025–2026 BTV season, with 13 European countries already reporting cases.

England alone has recorded 12 cases of BTV-3 in cattle and sheep since mid-July, while France has seen an explosive surge in both BTV-3 and BTV-8 cases. 

In July, France reported 1,104 outbreaks of BTV-3, compared to just 13 in June, and 985 cases of BTV-8, up from 75 the previous month. Italy has also seen a sharp rise, with 468 BTV-8 cases in July, nearly five times higher than in June.

“This was the first report of BTV-8 in the country,” DEFRA noted of Bulgaria’s July outbreak, adding that epidemiological investigations and vector control measures were immediately implemented in the affected areas.

Rising risk under warmer conditions

The spread of bluetongue is strongly influenced by climate conditions that support midge activity. With higher-than-average summer temperatures across much of Europe, the risk of transmission has increased significantly.

DEFRA’s updated assessment has now raised the overall risk of bluetongue incursion into Great Britain to “medium”, meaning the disease occurs often, compared to a “low” risk last December. 

During the 2024 season, vaccines were available, but in insufficient quantities to effectively combat the situation, raising concerns about the continent’s ability to manage the ongoing outbreaks.

“Given the increase in the number of cases in Europe and the increased temperatures suitable for onward transmission, the risk of incursion of BTV from all routes has now been increased to medium,” the agency warned.

For farmers in Bulgaria and across the continent, the resurgence of BTV-8 in particular is alarming. This serotype was responsible for devastating outbreaks in northern Europe in the mid-2000s, causing heavy livestock losses before vaccination campaigns brought it under control. 

France has already ordered millions of doses of BTV vaccines and launched a nationwide campaign to protect its flocks.

Safeguarding livestock

Authorities in Bulgaria have urged vigilance among farmers, stressing the need to report any unusual symptoms in their animals. Clinical signs in sheep include fever, swelling of the head, ulcers in the mouth, and sudden death in severe cases.

As the virus advances across borders, livestock owners are bracing for potential economic fallout, particularly in countries where vaccination programs are not yet widely deployed. 

With Europe on alert, experts caution that the coming weeks will be critical in determining the scale of this season’s outbreak.

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