THREE swans have been found dead with the virulent H5N1 strain of bird flu, it emerged yesterday.
Other birds are being tested at Abbotsbury Swannery, near Weymouth, but officials have so far ruled out a cull.
A member of staff found the mute swans in the Chesil Beach beauty-spot area of the county during routine surveillance three days ago.
Last night, a control area had been set up, within which bird owners must isolate their flocks from wild birds.
Officials are working to determine how the virus spread. No disease has been found in domestic birds, and a wild-bird surveillance programme is to be carried out.
Deadly H5 is one of the most contagious strains of flu among birds – but the chances of human infection in the UK are said to be extremely low. In March 2006, a whooper swan found dead in the harbour at Cellardyke, near Anstruther, Fife, tested positive for H5N1.
Acting chief veterinary officer Fred Landeg said: "Our message to all bird-keepers is that they must be vigilant." The Prime Minister, Gordon Brown, insisted the government would do "everything we can" to stop the spread of infection. He added: "We have had to deal with this issue before and we have placed protection zones around the affected area."
An expert on infectious diseases said the latest outbreak may have been brought to the UK by migrating birds.
Dr Robert Paul Yeo, from Durham University's Wolfson Research Institute, said: "The source of the bird flu in this case could be migratory birds over-wintering in the UK.
"The virus is being increasingly detected in birds all over Europe so, unfortunately, it was not unexpected that it would reappear in the UK. It reinforces the need for monitoring wild-bird deaths for the presence of the virus."
A cull has been ruled out because ornithologists fear this may disperse birds further.
The Department for Food and Rural Affairs has set up two restricted areas – a wild-bird control area and a larger wild-bird monitoring area.
The control area extends approximately 15 miles to the south-east of Abbotsbury, and includes the town of Weymouth, Chesil Beach and the Portland Bill headland.
The Royal Society for the Protection of Birds (RSPB), which has two wetland nature reserves near Abbotsbury, said it would increase the surveillance of wild birds on its sites in Dorset, Devon and Somerset.
Dr Mark Avery, the RSPB's director of conservation, said: "We are facing yet another outbreak of bird flu; this time the circumstances are consistent with the disease arriving in wild birds.
"Worldwide, this virus has been transmitted via a variety of routes, only one of which is through the movement of wild birds. Others include poultry movements, direct human transfer and the wild-bird trade, which is now banned in the European Union."
Dr Avery said it was still unclear how the virus had arrived in Dorset. "It is unlikely to have involved the swans directly, as this population is highly sedentary," he said.
The Abbotsbury Swannery is a reserve for free-flying swans and wild birds and is part of an internationally important wetland. Records of a swannery on the site date back to 1354.
It has been closed to the public for the winter since October and is due to reopen on March 15.
John Houston, from Abbotsbury Swannery, which holds 600 swans, said staff were working closely with Defra officials. He said: "We are very concerned, but we have been encouraged by Defra's comments about outbreaks in wild ducks. In those, experience has been a very low mortality of the ducks, and almost immediately there has been a build-up of immunity to the virus within the ducks."
He said staff entering the site were wearing protective suits, and removing them and disinfecting themselves on leaving.
The full article contains 651 words and appears in The Scotsman newspaper.
