Bluetongue virus threat to UK

Britain's farmers are facing their greatest ever crisis this weekend. A second virulent animal disease is threatening to sweep through the country at the most critical time of year.

Two teams of government vets worked through last night, frantically analysing hundreds of blood samples, after Britain's first case of the lethal bluetongue disease was found in an elderly cow on a children's " petting" farm near Ipswich yesterday. Professor Peter Mertens, who is leading the investigations at the Institute for Animal Health at Pirbright, told The Independent on Sunday late last night that "the door is open" for repeated infections of the disease, which has no known cure and can kill 70 per cent of the animals it strikes.

Earlier yesterday, the Government's chief vet, Debby Reynolds, said another farm – the sixth in less than two months – had been found to be infected with foot and mouth at Beaumont Farm, Old Windsor

The Prime Minister, Gordon Brown, had barely emerged from an emergency meeting of the Cobra crisis committee on the foot-and-mouth developments when he was told of the latest plague to hit his premiership. The infected cow is to be slaughtered.

The crises threaten to hit farmers with a deadly double whammy at a vulnerable time. Sheep farmers make almost their entire annual income by sending their animals for slaughter during the next few weeks, and livestock has to be brought down from the hills to their winter pastures.

Bluetongue – whose imminent arrival in Britain was exclusively predicted by the IoS last month – after it had spread northwards in Europe as temperatures have increased due to global warming – is more deadly than foot and mouth, and is even more difficult to control. It is spread by midges, which can carry it over far greater distances, causing far greater swathes of the countryside to be sealed off.

Restrictions on animal movements have to be imposed for 150km around an outbreak of bluetongue, 15 times more than for foot and mouth. Meat exports would be banned, and experts fear it could be two years before they were given the all clear again.

The Department for the Environment, Food and Rural Affairs was trying to calm fears by saying that that it could not be certain that there had been an outbreak of bluetongue until another animal was found to be infected.

It has estimated that the plague could affect 10 million sheep and nine million cattle in Britain. It added that "UK sheep breeds are particularly susceptible, and have no immunity". No vaccine exists against the strain of the disease most likely to have arrived in Britain.

Last night Professor Mertens, who is head of the Arbovirus Research Group at the Institute for Animal Health, broke off from his investigations to tell the IoS that his team was testing "at least 300 or 400 blood samples" taken from livestock around the Ipswich area to identify the strain of the virus, and to see whether it has spread.

He said: "On the Continent, the disease has gone ballistic; there have been thousands of outbreaks in Europe in recent weeks. Everything is pointing to this [the case in Britain] having come from an infected midge blown in from the Continent. The Met Office is working overnight to make predictions on wind movement to identify the areas at greatest risk."

But he added: "Midges don't normally travel on their own, but in large numbers. The discovery of an infected animal proves that the door is open and it's now a question of how many midges came through it."

Q&A: all about the deadly insect-borne disease

What is bluetongue?

Bluetongue, known as BTV8, is an insect-borne viral disease that affects ruminants, including sheep, cattle, deer and goats. It is transmitted by the 'Culicoides imicola' midge. Sheep are most at risk from the disease, which gets its name from the way that sheep's tongues can turn blue as a result of pressure from the intense swelling. Symptoms include swelling of the neck, ulceration of the mouth, nose and eyes, and lameness. It is most commonly seen in late summer and autumn.

Where has it come from?

Discovered in South Africa, bluetongue has since been recognised in most countries in the tropics and sub-tropics. Since 1999 there have been outbreaks in Greece, Italy, Corsica and the Spanish Balearic Islands, and cases in Germany, Belgium, the Netherlands, France, Croatia, Luxembourg, Bulgaria, Kosovo, Macedonia and Yugoslavia.

How does it spread?

Bluetongue can't be transmitted directly between animals. The virus is spread when a midge bites an infected animal and then bites an uninfected animal. Defra says the likelihood of transmission by unhygienic practices can't be excluded.

Is it deadly?

Yes, although it is harmless to humans. The most virulent strain of the virus can kill up to 70 per cent of infected sheep in two weeks.

Why has it arrived now?

Since the virus can survive on the same latitude as southern England, all we need is for wind to carry the midges across the Channel.

Ruth Elkins