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August 31, 2005

Reply to Web and Magazine articles on the potential for a flu pandemicAvian Flu Watch

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The Sunday Times - Britain, August 28, 2005

Focus: Atishoo, Atishoo, we all fall down?

www.timesonline.co.uk/article/0,,2087-1753479_1,00.html


Focus: A deadly bird flu, lethal to some animals, is spreading towards Britain. How serious is the threat to humans and what can be done to counter it? Jonathan Calvert, Sarah-Kate Templeton and Will Iredale report

It is the drug of the moment and Ken Livingstone, the London mayor, has ordered 100,000 courses of it. Several British companies are believed to be building stockpiles. Some individuals are said to be paying three times the retail price trying to buy illicit supplies through overseas websites.

The drug is Tamiflu, a prescription antiviral medicine thought to be the only protection available against a potential doomsday virus winging its way towards Britain.

Earlier this month a deadly bird flu, which has been spreading out from Asia, reached Russia. Yesterday a suspected case was reported in Finland, but the exact strain is not yet clear.

The H5N1 virus has killed tens of millions of animals, particularly chickens in Asia, but also other species. So far the strain has infected very few humans — only about 120 — but in those it has attacked it has been highly lethal. Half of them died.

The fear is that H5N1, like all flu viruses, will continue mutating and could turn into a strain that infects humans and passes from one person to another as easily as the common cold.

“If we do get human-to- human transmission, millions will die,” said Dr Nigel Higson, chairman of the primary care virology group.

“With huge numbers of people using air travel, it will move round the world very quickly. A large proportion of people in Africa would die. In western countries where we will hopefully have an avian flu vaccine and antivirals, 25% of the population will be infected and the death rate will be between 3% and 10% of the population. The fatalities will not just be the sick and elderly.”

Experts believe such a pandemic could cause a catastrophe on the scale of the 1918 Spanish flu that killed 50m people in 18 months.

Last month the Department of Health invited manufacturers to tender for a contract to develop and supply a vaccine against the strain. It is also spending up to £100m buying 14.6m courses of Tamiflu — an indication of how seriously it is taking the threat.

There is one big unknown: whether the virus can or will become transmissible between humans. Scientists have little evidence that it can do so at present and nobody knows whether it will be able to do so in the future.

“Although we expect this virus to become a pandemic we have no proof as yet that it will happen,” said Higson.

“To have a pandemic we have got to have a new virus.”

FLU is one of the most mutable viruses in the world, constantly shuffling its array of genes into new forms. The type known as H5N1 is thought to have originated in ducks from the Guangdong province of China in the late 1990s and drew particular attention because it proved devastating in poultry.

Almost every chicken that contracted H5N1 was dead within 48 hours. In 1997 the first human cases emerged during an outbreak on poultry farms in Hong Kong. Eighteen people suffered respiratory infections and six died.

Although more than 1.5m chickens were slaughtered in Hong Kong in an attempt to eradicate the virus, it managed to survive elsewhere — some animals can carry it without dying — and came back even stronger than before.

In January 2003 a tougher “Z” strain emerged in Thailand and Vietnam, capable of killing rats and later pigs. It also killed 45 tigers that were fed raw chicken in Thai zoos; more than 100 others had to be destroyed after becoming infected. National authorities ordered the slaughter of more than 120m chickens as the strain spread to Cambodia, China, Indonesia and Malaysia. This summer more than 120,000 poultry in six regions of western Siberia were destroyed after the discovery of H5N1.

Wild species — in particular bar-headed geese — were found to be infected in Siberia and Mongolia, which witnessed the mass deaths of birds around Lake Erhel in its Huvsgel province.

Several experts feared that the outbreaks had brought the virus within range of Europe through the flightpaths of migrating birds.

In Holland — where a similar avian flu outbreak five years ago led to 30m chickens being culled — officials last week compelled farmers to bring all their poultry indoors.

John Oxford, professor of virology at Queen Mary’s School of Medicine in London, called on Britain to take similar precautions and Bob McCracken, president of the British Veterinary Association, warned that migrating birds would “inevitably” carry bird flu to the UK at some stage.

However, Debbie Reynolds, the government’s chief veterinary officer, was more cautious after discussing the threat with European Union experts last week; she said the risk of the virus reaching Britain was “remote or low”.

Nevertheless, wildlife is being monitored around the country for any sign of avian flu. If it does arrive it could could easily spread across a range of wild birds — waterfowl are particularly vulnerable — and other animals.

Nor is it simply a problem for the countryside: many migrating birds land at wetlands near cities, such as Barnes, west London, and Martin Mere near Liverpool. Domestic cats that eat H5N1- infected birds could catch the virus, as has proved to be the case in Thailand.

So far studies of the virus’s human victims have concluded that they mostly contracted H5N1 through close contact with diseased or dead birds. The virus is found in both the faeces and raw meat. Most infections have occurred during the slaughter and defeathering of poultry for cooking. It is common in Asia to buy a live chicken at the market and take it home to eat.

Over the past year health officials in Thailand and Vietnam have also investigated three cases that could be the first evidence of transmission between humans.

In each case the victims had cared for an infected family member and then developed the virus several days later. Health officials have not ruled out the possibility that the virus was transmitted by a shared meal or some other exposure in the home.

If there is any human-to- human infection it is extremely limited at present and it is notable that previous H5-type flu viruses have not generally been transmissible between humans.

However, all three global influenza pandemics in the past 100 years have been linked to strains of bird flu that adapted to humans. While scientists emphasise that this risk is always present, they are particularly concerned now because the H5N1 virus is so lethal.

Victims suffer coughing, headaches, fever, dizziness, diarrhoea and internal bleeding. The autopsy of one child who died from the disease last year is reported to have shown that his lungs had been “torn apart” as his natural defences tried to fight the virus.

Professor Neil Ferguson, an expert in flu epidemics from Imperial College London, said: “This particular bird flu variety generates more severe diseases in humans than most bird flu varieties. It would be more like the 1918 type of pandemic than the 1957 or 1968 pandemics . . . that is potentially a very severe event.”

There is also a belief among some experts that pandemics are cyclical and the next is overdue. Forecasting of such catastrophes, however, is an imprecise science. A mutation turning the virus into a form more infective to humans could happen anywhere in the world — or the virus might become less lethal or, indeed, it might not happen at all.

Health officials have cried wolf about flu before and been wrong. When a soldier suddenly died from swine flu in the US in 1976, experts feared an epidemic, predicting that 1m Americans might perish.

President Gerald Ford ordered a mass vaccination of Americans despite the doubts of drug companies over being able to produce enough vaccine swiftly and safely. The flu epidemic never materialised and the US government paid $90m to claimants who suffered serious side effects from the vaccine.

IN judging how to react there are other factors to consider, too, principally the practical limits on protecting yourself. At present there is no licensed vaccination against H5NI and there is not likely to be one in the near future.

Three weeks ago the National Institute of Allergy and Infectious Diseases in America reported initial success in trials on a vaccine developed by Sanofi Pasteur, the pharmaceutical company. But the vaccine has yet to receive regulatory approval, which could take months.

It would also take years to produce enough vaccine to immunise the whole of Britain, and by then the virus strain could have changed out of recognition.

Marie-José Quentin-Millet, head of research at Sanofi Pasteur, describes its new vaccine as merely a “dress rehearsal” to build scientific knowledge so that it can be adapted if and when a strain of the virus more infective to humans emerges.

In reality, it is likely that a flu epidemic could be months old by the time anyone gets a vaccination. Even if a suitable vaccine could be produced, few doses would reach the general public. A report by the Department of Health says: “International demand for vaccine will be high. Vaccine will have to be distributed equitably and administered to predetermined priority groups first, according to nationally agreed recommendations.”

The priority groups set out in the report are frontline health workers followed by vital services such as police officers, firemen, the army and undertakers. Most of the population are very unlikely to be offered a vaccine. Given these limitations, the health department has chosen to make its block purchase of Tamiflu. Made by Roche, the drug can be used to protect against contracting the virus or to alleviate the symptoms of those already infected. The full order of 14.6m doses ordered by the health department will not be delivered until March 2007. At present the government has a stockpile of 900,000 doses and they would be offered first to the priority groups. For this reason several organisations are trying to acquire their own stocks, including the London mayor’s office, which spent more than £1m buying antivirals to protect key workers in the capital. Doctors advise strongly against individuals hoarding drugs. “If individuals stock up with pre-orders, the medication will not be there for those who need it when there is an outbreak,” Higson said. There is another problem, too: many of the people who have been infected by bird flu were given Tamiflu, yet they still died. So in the absence of medication, what else could you do if there were an outbreak? According to the contingency plan people would be advised to avoid public transport, crowds, long queues and anywhere else they might encounter carriers of the virus. Most effective, it seems, will be to stay at home and wait until the outbreak is over.

Additional reporting: Nicci Smith, Brussels

Posted by dymaxion at August 31, 2005 12:32 PM

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