Understanding Avian Influenza
Reason to be fearful?
By Tom Geoghegan
BBC News Magazine
The British public is being asked to look out for suspicious bird deaths amid fears that avian flu could reach the UK. But should humans be worried and what else is being done?
Suddenly migrating birds carry a hint of menace.
New instructions issued by ministers request that anyone who sees disease in certain types of birds should report it on a special helpline.
Although the risk is deemed low, the fear is that birds coming to the UK, especially from Russia, could be carrying the deadly H5N1 strain of the avian flu virus, which has killed 60 people in Asia.
Humans contract it through close contact with live infected birds. One way is by inhaling infected faeces which have dried out and infiltrated the air.
The latest outbreak in Turkey led the EU to ban all imports of live birds and feathers and some reports claim the virus could become the biggest threat facing the UK population.
But all the victims are thought to have had close contact with birds, and there's no evidence the virus can be easily transmitted between humans, so why the talk of a pandemic flu?
The size of the risk to the UK is very difficult to predict, says virologist Colin Fink.
"The change that's got to take place before a human epidemic starts is the organism has to develop the ability to pass between humans and at the moment it doesn't.
"It only passes between birds and, if there's a big enough dosage, occasionally birds and humans.
"Provided it stays that way, there's no problem, but evidence suggests some similarities to the 1919 epidemic and we don't know how that started - maybe in pigs and ducks in China and then moved across."
A pandemic occurs when a virus emerges that is so different from previous strains that few people have any immunity to it.
Any confirmation that H5N1 has become capable of human-to-human transmission will increase the World Health Organisation's pandemic alert level to its highest level.
In practice, that could happen if H5N1 infected someone who also had an ordinary flu virus and the two combined to make a new strain which would spread very fast.
Pandemic flu occurs about three times a century; the Spanish flu of 1919 killed up to 40m people globally, including 250,000 in the UK. Significantly, its victims were mostly healthy young adults.
No-one knows why this group was so affected, says Dr Fink, or whether the same would apply in a new pandemic.
The request for vigilance from bird-spotters is the first time the public has been asked to help within the UK, although people visiting Asian countries affected have been issued with travel advice.
Holidaymakers are told to avoid contact with live animal markets and poultry farms, because the droppings of infected birds are known to harbour the virus. They should also not bring any live birds or poultry products back to the UK.
The government has issued a detailed pandemic plan, setting out what it would do to minimise the spread of infection, such as stopping large public gatherings.
It has bought 14.3m antivirals, enough to cover 25% of the population, as recommended by the World Health Organisation. Half will be ready by March and the full number by December 2006.
"If for some reason demand exceeded supply, key workers would be prioritised," says Department of Health spokeswoman Vicky Wyatt. "And then we would draw up a national treatment priority list on the basis of the at-risk seasonal flu groups - over 65s and vulnerable groups such as diabetics."
"However we don't know the precise nature of the virus so it may be it affects other groups in which case we would need to take this into account when we prioritise."
Several potential vaccines are being developed but their suitability depends on how much a pandemic strain might have mutated from the original H5N1 virus strain used to create the vaccine in the first place.
The government proposes to buy two million doses as a "strategic stockpile" to be used on priority groups while a vaccine against the exact strain is manufactured.
Farmers have been warned to adhere to the guidance issued in the wake of foot-and-mouth, which sets out how to minimise the threat of infection. It covers the moving of livestock and keeping premises clean.
Consumers of chicken have nothing to worry about because avian flu is not a food-borne virus.
But bird-spotting is not the only way the public can help.
Getting informed about the threat and learning how to stop infection spreading would be useful, says Sarah Clark at the Health Protection Agency, who recommends reading a leaflet entitled Pandemic Flu, found on the Department of Health website (see internet links).
"It would be useful to understand the issues and understand what things mean," she says. "That's what people can be doing at the moment."
Understanding Avian Influenza