THE discovery of the Asian strain ofthe H5N1 strain of bird flu in Suffolk marks a grim development for the UK.Thegovernment dreads the prospect of the virus spreading and took immediate steps to seal off the farm and treat the 1000 workers with the anti-viral drug Tamiflu.

It also promised to cull all 159,000 birds on the Bernard Matthews poultry farminHoltonasaprecautionary measure to contain the disease. Experts believe the source of contamination couldhavebeenasmallwildbird, raising fears that other birds outwith the farm may also be infected.

Suffolk is the first case to involve home-bredbirds.Lastyearaswan thought to have contracted the disease in Germany washed up in Cellardyke, Fife, in the first H5N1 case in Britain.

Although it cannot be easily transmitted to humans, experts fear the virus could mutate, triggering a pandemic. Defrayesterdaymovedswiftlyto reassure the public by ordering the slaughter of 159,000 turkeys on the farm and establishing a protection zone of 3km, along with a surveillance zone of 10km around the premise.

Defra also introduced a restriction zone - in which poultry must be kept isolated from wild birds and movements must be licensed - covering 2090 sqkm of east Suffolk and southeast Norfolk.

Defra also announced it is revoking the licence on bird gatherings, bird shows and pigeon racing. The Scottish Executive confirmed the cancellation of all bird gatherings, although it admitted thereare"nodirectimplications" following the discovery in England.

Defra workers - and others who had been on the Suffolk farm when the first dead birds were discovered on Tuesday - have been given the anti-viral drug Oseltamivir, more commonly known as Tamiflu. Enough of the drug has been stockpiled to inoculate 14.6 million people in Britain.

Protective clothing was also handed out to experts working on the farm. However, there were fears about how the virus could be contained with so many people working at the farms.

A Defra spokeswoman said: "The HealthProtectionAgencyisfully engagedwithriskassessmentsfor Bernard Matthews workers and on-site personnel. As a precautionary measure theyhavebeengiventheanti-viral medication Oseltamivir."

Major events such as next month's Spring Bird Show in Stafford, attracting 5000 people who trade in exotic species, face cancellation.

Although the source of the outbreak is so far unknown, Professor John Oxford, a virologist at the Queen Mary's School of Medicine in London, said: "The most likely explanation is that a small bird has come in through a ventilation shaft. I don't think it has made any difference as a threat to the human population though. One good thing about this virus is that it's easily destroyed. You can kill it off with a bit of detergent."

Avian flu expert Dr Colin Butter, at the Institute of Animal Health, said it was important to discover if the farm was the "reference" case - the first place the strain emerged in poultry. If that were the case, the most likely source would be from the wild bird population.

He said that as this is not a migratory time of year, such an outbreak could be an "unhappy chance event" or could indicate a significant level of the disease in wild birds indigenous to the UK, which in turn would make the virus harder to stamp out.

Neil Parish, chairman of the European Parliament'sagriculturecommittee, said: "This outbreak has been detected early and action taken swiftly to contain it. The EU and Defra have put in place someverystringentproceduresto prevent an outbreak from spreading.

"Of course, we must all be vigilant, but there is absolutely no need for panic or hysteria. There is always a danger that an outbreak can occur at any time. What we have got to do is make sure Defra have got this under control."

THEgovernmenthas been preparingforamajor outbreak of the deadly diseaseintheUKeversincetheH5N1strainbegan killing people in Asia. Last year, a Cabinet committee discussed the worst-case scenario of hundreds of thousands of deaths. The public was shocked when leakedHomeOfficecontingency documents suggested 320,000 could die from H5N1 if it mutated into a virus attacking humans.

The government's fears of an epidemic led to preparations involving Downing Street and police forces for full-scale practicedrillsbasedon anH5N1 outbreak at three places in England and Wales. However, the plan was cancelled whentheCellardykecaseemerged, presentingtheauthoritieswiththe chance to react to a real situation.

Financial institutions have simulated how they would be able to run their businesses in the event of mass casualties. Some companies have practised operating with significantly reduced numbers of employees. The cost of a pandemic on the country's economy is likely to run into billions of pounds.

More than 30,000 birds were slaughtered after chickens with the H7 strain of the virus were slaughtered as a precaution near Dereham, Norfolk, in April last year. The same month, 10,000 birds were culled in Leipzig, eastern Germany, after H5N1 was found. In May, two Norfolk poultry farms had 15,000chickensculledafterthey contracted the H7N3 strain of bird flu.