Spread mainly by midge bites, the virus was confirmed in a sheep in Cornwall in September 2025 in the first recorded case in the UK in 17 years.
This strain was introduced into Cornwall from midges blown in wind from northern France, said Gubbins.
With cases clustered in the south of France this year, external, Gubbins said the likely scenario was the virus “went from one season to the next” in parts of the UK.
Bluetongue, which causes a drop in milk production in dairy cows and lameness in sheep, can be transmitted to their offspring.
“The virus has essentially done that in the south-west of England, and then when the new crop of lambs and calves were born, it’s come during a very warm period – and that is very favourable for bluetongue transmission,” said Gubbins.
“In normal weather conditions we’d expect that to be one to two weeks during the height of summer – but for the past few months it’s been a few days to a week.
“It’s been much faster than we’d normally expect.”