An animal disease which causes severe birth defects and miscarriages in livestock could spread across Britain this year, experts believe.
There have been 276 cases of Schmallenberg virus, which first emerged last year in the Netherlands and Germany, in cattle and sheep on farms across southern and eastern England since early 2012.
Adult animals which were infected during their pregnancies last autumn by virus-carrying midges, thought to have blown across the English Channel, gave birth to deformed or stillborn lambs and calves this spring.
Despite midges dying off during the winter months, tests since March on some 150 cattle and more than 1,000 sheep belonging to the Royal Veterinary College showed a small number of animals which had previously tested negative for the disease have now tested positive. Two of the college’s small herd of alpacas have also tested positive for Schmallenberg.
The results revealed the virus had survived the winter and was still circulating in the UK in the current midge season.
Professor Peter Mertens of the UK’s Institute of Animal Health said: “On the basis it spread last year very effectively, I see no reason why it couldn’t cover most of the country this year.”
While the impact varies, with as many as 30% of young being born deformed or stillborn on some farms, the incidence rate is gen-erally low — around 2% to 5% of flocks or herds giving birth to deformed offspring, said UK chief veterinary officer Nigel Gibbens.
“So far we have seen a relatively limited impact from the disease on English farms and those in the rest of Europe, but we understand that it can be distressing for individual farmers,” he said.
Schmallenberg causes only mild symptoms in adult sheep, cattle, and goats, with the main problems including reduced milk in dairy cows, fever, and diarrhoea lasting just a few days, and they are likely to be immune to future infection. For the adult animals “it’s like getting a cold”, Prof Mertens said.
The deformities in youngsters can be very severe, ranging from cows born without proper brains, damage to the central nervous system, and locked leg joints which in goats in particular can cause major damage to the mothers during birth.
There is no evidence of any health risk to humans, the experts said.
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