By Cole Moreton
9:00PM GMT 25 Feb 2012
The Schmallenberg virus causes lambs to be born dead or with serious deformities such as fused limbs and twisted necks, which mean they cannot survive.
Scientists are urgently trying to find out how the disease, which also affects cattle, spreads and how to fight it, as the number of farms affected increases by the day.
So far, 74 farms across southern and eastern England have been hit by the virus, which arrived in this country in January.
A thousand farms in Europe have reported cases since the first signs of the virus were seen in the German town of Schmallenberg last summer.
The National Farmers Union has called it a potential “catastrophe” and warned farmers to be vigilant. “This is a ticking time bomb,” said Alastair Mackintosh, of the NFU. “We don’t yet know the extent of the disease. We only find out the damage when sheep and cows give birth, and by then it’s too late.”
It is unclear exactly how the disease arrived in Britain, but the leading theory is that midges carried the virus across the Channel or North Sea in the autumn. However, scientists cannot yet rule out transmission of the disease from animal to animal.
Infected ewes do not show any symptoms of the virus until they give birth, with horrific results. Farmers have described delivering the deformed and stillborn animals as heartbreaking.
The lambing season has only just begun, which means that the full impact of the disease will not be felt until the weather warms up and millions more animals are born.
On the Continent, some farms have lost half of their lambs. So far the worst hit in Britain have lost 20 per cent, according to the Department for Environment, Food and Rural Affairs (Defra).
Approximately 16 million lambs are born in Britain every year and sell at market for about £100 each. The effect of the disease on farms that are already struggling in the downturn could be severe.
“For any business to lose 20 per cent of your stock would be a huge blow,” said Mr Mackintosh. “For a farmer to lose 20 per cent of your flock is catastrophic. If it was 50 per cent you would be put out of action.
“I was talking to one who has 10,000 sheep. If he loses even five per cent of the animals born this year, that’s a hell of a lot of lambs. I know another who says 10 per cent of his ewes have become barren. He has 6,000 ewes, so that is 600 animals producing nothing.”
The Food Standards Agency has sought to allay any fears about eating lamb, although little is known about the virus so far.
The Agency said: “Any risk to consumers through the food chain is likely to be low. No illness has been reported to date in humans exposed to animals infected with Schmallenberg virus.”
The worst affected counties are Norfolk, Suffolk, East Sussex and Kent, but the virus has spread all along the south coast to Cornwall.
Farmers fear the disease may spread to larger flocks in the north of England, Wales and Scotland. In Europe, Germany, Holland and France have suffered worst, while recent cases have been reported in Italy and Luxembourg.
John, a farmer from East Sussex who wanted to remain anonymous, said he had lost 40 out of 400 lambs so far, at a cost to his business of more than £4,000.
“I’ve had to put more lambs down in the past month than I have done in the past 20 years. Every one is a serious blow to our finances. But it’s an emotional thing too,” he said.
There are also fears that the virus may be seen later this year among cows, which have a longer gestation period.
Five of the British farms have seen cattle affected, with calves aborted at six months of pregnancy.
Cows are thought to be more robust than sheep and therefore more resistant, but Schmallenberg virus could still reduce milk yields and put pressure on a dairy industry that is already suffering, says Mr Mackintosh. “From what I hear, we are likely to see weak calves that take a lot of expense and nursing to get going again. Having to do that will hit a business hard.”
The last confirmed midge-borne virus to hit the British farming industry was bluetongue in 2007, but a series of trade restrictions and a vaccine averted disaster.
This time there is no vaccine, and Defra says a ban on imports would not work, because the disease “is already here”. A spokesman said: “Defra is taking this seriously. We track emerging diseases. There is work going on across Europe and the amount we know is improving rapidly. We are keeping everything under review.”
Its website says “farmers and vets should remain vigilant and report any suspicious cases to AHVLA [the Animal Health and Veterinary Laboratories Agency] for testing as part of our enhanced surveillance”. However, farmers are not yet legally required to notify authorities of an outbreak, leading some in the industry to fear it may already be much more widespread than figures suggest.
Nigel Miller, the president of the NFU in Scotland said: “The escalation and range of cases is deeply concerning and some experts are now suggesting that the volume of cases being seen is an indication that this is, in fact, the second year of infection.
“If that is the case then it raises the worrying prospect that the virus may have an effective overwintering mechanism.”
The AHVLA identifies Schmallenberg as one of a group of viruses “typically primarily spread by biting insect vectors, such as midges and mosquitoes, although the routes of Schmallenberg virus transmission have not yet been confirmed. The potential for direct transmission (ie direct from one animal to another) is therefore, as yet, unknown.”
It said: “There is unlikely to be a risk to human health from Schmallenberg virus; but this is not yet certain.”