The number of cases of the deadly bird flu virus is increasing around the world as scientists struggle to combat the disease that is now threatening to jump species and infect humans.
The news came as Britain confirmed its first ever case of H5N1 in a farm in Suffolk, England. More than 160,000 birds were to be slaughtered as the country's farming industry went on high alert for more outbreaks.
Japan and Nigeria have recently reported a series of cases of the lethal virus while China, Egypt, Russia, South Korea and Vietnam have also revealed they have suffered outbreaks in birds and in humans in the past two months. Indonesia last Wednesday began a mass bird cull in Jakarta, its capital. A total of 164 people are now known to have been killed by the disease across the globe.
The rapid spread of avian flu can be traced to the fact that the H5N1 virus is mutating as it spreads through birds and a variety of mammals including cats, tigers and pigs, said Robert Webster, a flu researcher at St Jude Children's Research Hospital, in Memphis, Tennessee.
Last Saturday night UK health officials insisted the risk to the public was at this stage still negligible. They had set in motion a series of emergency measures aimed at halting the spread of the disease among poultry in Britain. All the turkeys on the affected farm at Holton near Lowestoft, the largest poultry center run by the turkey breeder Bernard Matthews, were to be culled. On Saturday piles of slaughtered birds were already being scooped into open tractor trailers before being removed for incineration.
In addition, a 3km exclusion zone was set up around the farm. All poultry within that area were to be kept indoors and tested for the H5N1 virus. A further 10km zone was established in which all movements of poultry are banned.
Other measures will include a ban on bird shows, poultry markets and pigeon racing across the country. This follows a decision by the Department for Environment, Food and Rural Affairs (DEFRA) to revoke the national general license on bird gatherings. Last Saturday the National Farmers Union's president, Peter Kendall, said his organization had warned all farmers to be vigilant.
A spokesman for Bernard Matthews said his organization could confirm there had been a case of H5N1 avian influenza at its Holton site.
"However, it is important to stress that there is no risk to consumers," he added.
Andrew Landeg, the government's deputy chief veterinary officer, also revealed that he had called in expert ornithologists in a bid to understand how wild fowl -- now thought to be the most likely source of the Suffolk outbreak -- might have carried the virus into one of the 22 turkey breeding sheds at the farm and to understand what other areas of the country might now be at risk of outbreaks.
On Saturday it was revealed that DEFRA had already identified several areas in Britain in which farms were considered to be at particular risk of picking up H5N1 from infected wild fowl. The farm at Horton was one of these.
Avian flu expert Colin Butter at the Institute of Animal Health said it was now crucial that veterinary scientists discover if the farm was the first place this strain of avian flu had emerged in poultry. It could be that the outbreak was an "unhappy chance event" or it 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.