The Schmallenberg virus is still circulating in the UK, scientists have confirmed.
Tests on 150 cattle and 1,000 sheep showed animals that had originally tested negative for Schmallenberg subsequently became positive between March and June.
Scientists at the Royal Veterinary College and the Pirbright Laboratory said the virus – which is transmitted through midges, causing birth defects in cattle and sheep – had survived the winter and was still circulating during the current UK midge season.
“We had hoped the virus might simply burn itself out and fail to make reappearance this year, but that has not been the case,” said Professor Peter Mertens.
“Thankfully there are unlikely to have been many animals at the critical stage of pregnancy during the midge season so far, but as the year goes on that will obviously change.”
Mertens said it was unlikely a vaccine would be available for use in the UK this season, so it was important to consider other control measures to protect British herds.
Chief veterinary officer Nigel Gibbens said the impact of Schmallenberg on the UK had been small to date, but outbreaks of the disease could be distressing for individual farmers.
“We are monitoring which areas have had infection and which haven’t, to help farmers consider and plan for the likely impact,” he added.