Bird-flu virus flies to Europe
BANGKOK
The bird-flu virus that has leapt to Russia and Kazakhstan after causing deaths and huge economic losses in Asia risks spreading further, borne by migratory birds crisscrossing the globe.
Wild birds are widely credited with spreading avian influenza far beyond its epicenter in the backyard farms of Asia, where the mingling of species gives virologists nightmares about the risk of mutation into a far deadlier form. And once deposited in a country, courtesy of the annual migrations, which take flocks of birds from Asia to the north during the European summer, the H5N1 strain moves among poultry with ease.
"Birds play a role in the primary infection of the country, but then after that there's no need for wildlife. It will spread very easily from one village to another through trade," said Joseph Domenech, the Food and Agriculture Organization's chief vet. "Given that it is a highly contagious disease, we were sure it could spread from one region to another, either through wildlife or through trade and movements of products. So this happened and we are not surprised at all."
While sporadic outbreaks continue to emerge in Asia, attention has now shifted to the discovery of the virus in poultry in parts of Russia and Kazakhstan, raising fears it will cross the Urals mountain chain into Europe.
The alarm has already been raised in western Europe, and French President Jacques Chirac has called for a strong international response to the new threat, warning it could develop into a major health crisis.
Domenech said that the risk of avian influenza creeping that far in the next few months is low, but that each time birds fly back and forth across the globe the risks of contagion at the avian "crossroads" increases. "If the virus is coming from wildlife, then next year or the year after it could happen that it goes to western Europe," he said.
The virus threatens to contaminate all the migratory paths, bringing the disease to Africa, South Asia, and the Middle East as well, he said.
Domenech said Europe has more weapons at its disposal to fend off bird flu than Asia, and a developed agricultural system that is easier to defend. But it also has a lot to lose in a financial sense. "We are very worried. If it comes to countries like those in western Europe it could be a very severe economic disaster," he said, listing poultry export bans and expensive changes in farming methods as among the fallout.
Apart from the economic threat, the spread of H5N1 also poses a hazard to human health, by increasing the chances of a mutation that could create a pandemic capable of killing tens of millions.
"The farther this virus is being spread, the more opportunity it has to infect humans," said Dick Thompson of the World Health Organization. "And when that happens there's also the possibility of reassortment with a human influenza virus and what we are concerned about in that case is that what might emerge is a pandemic virus able to jump easily from one person to another."
AFP
Huge stockpile of antivirals needed
PARIS
Up to three million courses of antiviral drugs will have to be stockpiled if Southeast Asia is to stand a chance of containing a human pandemic of bird flu, scientists have warned. Administering these drugs to key individuals and to residents of an area where the feared virus breaks out will be a vital part of any effort to restrict and then roll back the disease.
Their study published online by Nature simulated what would happen in Thailand if a mutated form of the H5N1 avian-flu virus erupted among its 60 million people.
To contain the pandemic, Thai authorities would have to move with great speed, setting in motion a prepared strategy when no more than 40 people have fallen sick, it says. They would have to distribute antiviral drugs such as oseltamivir, close schools, restrict travel, and isolate and treat all newly identified cases within two days. That way, the outbreak would be restricted to about 150 cases, below the threshold at which it would leap into the broader population and to other countries.
The authors, led by Neil Ferguson of Imperial College London, say this response "depends critically" on having a medical system capable of quickly diagnosing cases and of distributing the drugs. Their computer model is based on the premise that a pathogenic H5N1 virus would have a "reproductive number" of 1.8. This figure represents the average number of people that someone with the disease is able to infect. Thus, the higher the number, the more infectious the disease. The figure of 1.8 is consistent with past global pandemics of new flu strains.
Avian flu's natural reservoir is in migrating birds and poultry flocks in Southeast Asia. However, the virus in its present form does not transmit easily from human to human. The big worry is that it could swap genes with an ordinary flu virus, making it highly contagious among humans as well as lethal.
Another study, published online by Science, also used rural Thailand as a setting to simulate containment strategies for avian flu. In every scenario, early intervention--with antiviral drugs at the core--was found to be essential.
The reliance on antiviral drugs to dampen the outbreak stems from the fact that there is no proven vaccine yet for the H5N1 strain, and in any case there would probably be a delay of months before any vaccine could be manufactured and distributed.
AFP
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