2006-04-06-Britain braced for threat from virusUnderstanding Avian Influenza
2006-04-06-Britain braced for threat from virus
The discovery of a strain of bird flu found in a dead swan in Scotland yesterday brought the potential threat of the deadly H5N1 to Britain for the first time. It also triggered a number of responses which are in place to deal with any outbreak of the strain which can be fatal to humans if they come into contact with it.
A sample from the dead swan tested positive for "highly pathogenic H5 avian flu". H5 is a contagious strain and can be fatal to birds.
While further tests are being carried out to see if the bird was infected with the H5N1 strain, the first steps to reduce the danger posed to other birds and people were being put in place. Results from the further tests are expected today.
Once the virus in the swan was identified as a type of H5 avian influenza, a 1.8 mile (3km) protection zone was set up around Cellardyke, a small coastal town in Fife, nine miles from St Andrews, the area where the carcass had been found, according to the European Commission .
The virus will undergo further tests at the Veterinary Laboratory Agency in Weybridge, Surrey to identify exactly which type of the highly pathogenic H5 virus it is.
"We don't know exactly when that's going to come through," said Freda Scott-Park, president of the British Veterinary Association.
While the VLA carries out its tests, which could take up to 24 hours, the area of Fife where the bird was found will be monitored.
"The most important thing is the movements of birds and animals are going to be controlled in that protection zone. It's key that we don't have any spread of the virus beyond where the swan was found," said Dr Scott-Park.
"It comes down to looking for the forensics of the disease. They need to know if there are other birds affected. They'll have a good idea of the poultry in the area and we gather it's not an area that's got lots of poultry in it."
What no one knows is how many small flocks of birds there are in the are in the area. Vets will be going into the area immediately to make sure they know exactly where all the birds are. While the waiting is going on there will be a lot of activity going on to make sure the virus doesn't spread," said Dr Scott-Park. "That's identifying at-risk birds, giving advice to people who live in that area and making sure we all take our responsibilities seriously and act proportionately."
If the virus is confirmed as H5N1, the exclusion zone will be extended by six miles and movements of birds in the area might be halted, with farmers told to keep their animals inside. Because the virus was found in a wild bird, farmers can probably rest easier that their flocks are not in danger of being culled.
"It would be very unlikely not to be N1 but there is a possibility that it might be one of the other strains," said Dr Scott-Park. "H5N1 is the most likely one."
Around the country free range and organic producers have been told for weeks that they should be ready in just such an emergency and tests on poultry farms are likely to be stepped up.
Anyone who keeps birds within the protection zone round where the wild swan was found have already been told to take such precautions, and keep food and water sources protected, but far wider restrictions are likely if the case is confirmed.
For the moment only movement of poultry and eggs from farms within six miles of the suspect case is being banned but this could widen considerably if the European Union considers it necessary. Decisions will also have to be made on whether culling might be necessary.
The government has said this will be ordered where the risk of infection is high, while in lower risk areas premises will be placed under restriction for 21 days with regular veterinary inspections. For the moment however, it stressed the virus had not been found in any domestic birds.
Ministers will try to quell alarm pointing out that the virus is at present only limited to a case in a wild bird and that eating poultry still poses no risk to public health. Sales have plummeted in many countries where bird flu has been reported and with firms in the UK providing 850m birds for food each year and 9.6bn eggs the industry will be nervous of a BSE-like effect on production.
Poultry workers may be offered both seasonal flu vaccine and antiviral drugs to minimise the risk that the virus could mutate into a type more dangerous to humans. The government only completed a register of poultry owners last month and it is not certain it knows where all the farms are since those with flocks of fewer than 50 birds did not have to comply.
But avian flu is not easily spread, requiring extremely close contact with infected birds, particularly faeces.
Culling of wild birds is not an option, since shooting might well disperse flocks further. Culling poultry, if necessary, is likely to be done by gas on large battery farms, and mobile units could be sent round other farms. On some small units however, birds might have to be killed by wringing their necks.
The government has powers to vaccinate flocks as a precautionary measure, and many organic and free-range owners have been pressing for just such a move. But ministers are resisting the idea on scientific advice that it is too difficult, and it can take up to three weeks for birds to deliver immunity and some birds require two doses.
Quite apart from the huge practical difficulties, the vaccination will not stop birds being infected and shedding the virus. It might therefore mask the disease.
Two million vaccine doses have been ordered to protect zoo and other exotic birds. Defra said last night: "There is currently no indication that it is necessary to use vaccines."
The government's chief scientific adviser earlier ruled out the use of currently available bird flu vaccines in the event of a UK outbreak. Professor Sir David King said rare breeds of birds kept in zoos would be the only cases where vaccines would be feasible. The inoculation of organic or free range birds would not be recommended. Speaking after the National Farmers Union's annual conference in February, he said: "I would be very concerned about the spread with the current vaccine. What it means is that every time you vaccinate you have to increase surveillance because signs of the disease are not very obvious."
In the aftermath of the discovery of the dead swan the government insisted there was no public health risk but officials have planned a campaign of reassurance in case the deadly bird flu virus reaches Britain.
Ministers and the chief veterinary officer will unleash a media offensive in which they will seek to calm public anxiety by stressing the relative difficulty of humans catching H5N1 strain of the disease. But they will also warn that no one should handle dead birds.
Last night Dr Lesley Macdonald, NHS Fife director of public health, also sought to play down the health risk: "Whilst avian influenza cannot be ruled out at this stage, there is no reason for public health concern. Avian influenza is a disease of birds and whilst it can pass, with difficulty, to humans this requires extremely close contact with infected poultry, particularly faeces."
Those who have come into contact with infected birds - either members of the public who handle dead wild ones, or poultry workers - will be offered the seasonal flu vaccine to minimise the risk of infection. The belief is that those affected with the seasonal flu virus are more susceptible to other flu bugs; the vaccine reduces the risk of H5N1 crossing over.
The antiviral drug, Tamiflu, will also be given because it acts, after exposure, as a prophylaxis. Five million doses have been stockpiled so far, in the event of a pandemic, and a total of 14.6m - enough for a quarter of the population; the number predicted to be affected - will be in place by August.
Those who come into contact will be strongly advised to accept the vaccine but will not be automatically admitted to hospital. Instead, they will be urged to be on the lookout for symptoms, which are similar to other strains - fever, sore throats, coughs and muscle ache - as well as eye infections and pneumonia.
Anyone who presents with these symptoms, will be put in isolation in hospital, and samples sent to the Health Protection Agency's laboratory in Colindale, north London. There scientists will determine if it is a high or low pathogenic strain. The high strain is the one to have affected humans in the far east and Turkey.
The government has come up with a plan for mass evacuation of major cities if the strain mutates and passes from human to human.