[ANN]Bracing for worldwide bird flu

The Straits Times, Singapore Asia News Network

Bird flu is on the march. About 1,800 turkeys have died of the disease in Turkey, while 7,600 domestic birds have been culled. Last week, in response to laboratory confirmation that Turkey and Romania have been hit by the bird flu virus - which European Union Health Commissioner Markos Kyprianou said had "a direct relationship with the viruses recently found in Russia, Mongolia and China" - a ban on poultry imports from the two countries was imposed.

This development comes after U.S. President George W. Bush launched a "new international partnership" last month to fight bird flu, to which 16 countries immediately signed up. Then he called in bigwigs from three major vaccine makers for a meeting at the White House. It seems those in power are finally taking the threat seriously.

Last year, H5N1 exploded across Asia with bird infections in China, Japan, South Korea, Vietnam, Thailand and Indonesia, as well as possibly Nepal, India and Pakistan, where no virus was isolated. Earlier this year, clusters of human cases in Vietnam and in newly hit Cambodia, began to grow, with transmission to healthcare workers as well. Last week it was confirmed that the H5N1 virus has been found in dead birds in Turkey and in Romania - continental Europe`s first.

In late August, Finland had its first bird flu scare, when gulls in its northwest showed signs of H5N1. But this was later shown to be a "mild, low-pathogenic strain of avian influenza" of no risk to human health, according to the European Commission. Still, a study in which birds were banded with identity tags showed a bird from Finland ending up in Texas, President Bush`s home state. Perhaps the world`s most powerful office holder knows something the rest of us don`t.

Even back in May, several research groups visiting Vietnam had found small clusters of human cases of H5N1, especially in older people. They also found many people with mild cases of flu who tested positive for H5N1. So, too, did those in close contact with them. What this suggested was that the virus had improved its ability to spread human-to-human, even if it wasn`t killing or causing illnesses in a large number of people.

On June 30, this led the WHO to consider raising the threat level to that of a global pandemic, but its own testing showed up negative. No reasons were offered. Further samples were sent to a WHO lab in Hong Kong for confirmation. To this day, however, the results are not available.

Why the reluctance to raise the warning level? The reason is that it would require urgent action on getting an international stockpile of antiviral drugs deployed. It could also lead to restrictions on travel to an infected country. The political animal that it is, the WHO is loath to inconvenience its member-states.

But there is cause for concern. It is now common knowledge that migratory birds are spreading the virus in Asia - from China to Russia, Kazakhstan and Mongolia - and, now, into Europe.

However, it was not generally appreciated, until the outbreak in the Qinghai nature reserve in China earlier this year (where thousands of birds of different species died in an unprecedented fashion), that migratory birds were susceptible. What this means is that, this year, the bug has dramatically increased its geographical range via migratory birds. And now that H5N1 has been established in migratory birds, it virtually assures its worldwide spread over the next 12 months.

As the weather gets colder in the northern hemisphere, wild birds migrate to warmer, more southerly destinations. Infected birds can travel very far - some geese, for example, can fly 1,500 kilometers in 24 hours - and, because their migratory paths intersect, the H5N1 virus may also spread very widely.

Next, as the bug can now infect more species - including wild and domestic cats, civet cats, tigers, mice, ferrets and humans - the likelihood for more lethal mutations to appear rises even as its geographical reach grows. Also not generally appreciated is the fact that since H5N1 is being spread by long-range migratory birds, culling infected poultry on the ground - which may help in particular nations - will do little to stop its dramatic cross-border spread.

The unstable situation there is likely to deteriorate in the coming weeks as more birds migrate south, bringing new mutations that could recombine with the H5N1 that is already found in pigs, which seem to be able to carry the virus without obvious sickness.

There have also been reports of a strain called H7N1 co-circulating in West Java in Indonesia, which is efficiently transmitted from human to human, thus presenting a dangerous opportunity for the H5N1 to recombine its genes. Jakarta being a huge metropolis with an international airport doesn`t help matters.

Next, there is a mirror concern in Europe where birds are known to be infected with H7N7, a non-lethal strain which can be passed to humans who can then transmit it to other humans. As recently as 2003, this led to an epidemic of (merely) conjunctivitis in humans in the Netherlands, the virus seemingly causing the eye infection with no obvious flu symptoms.

Several of the genes in H7N7 isolated from these Dutch cases closely resemble genes found in H5N1 isolated from patients in Asia. If H5N1 begins to co-circulate with H7N7, the former could acquire gene sequences that allow efficient human-to-human spread.

Finally, the wild bird strain now circulating globally carries specific mutations first found in birds at the Qinghai nature reserve, making it significantly different from the H5N1 strain circulating in Vietnam. Yet the worldwide effort to create a vaccine by the drugmakers summoned to the White House is based on a 2004 strain isolated from victims of the illness in Vietnam. Their vaccines, even if produced in sufficient quantities and on time, are unlikely to be effective against the wild bird sequences.

That`s all the bad news for now. Here`s some better news.

This past week Paula Dobriansky, the U.S. Undersecretary of State for Democracy and Global Affairs, and Lee Jong-wook, the WHO director-general, were in Singapore, the first stop in their regional tour to discuss with governments ways of dealing with the pandemic threat. So something is moving.

Next, the current strain does share some of the most crucial genetic changes that occurred in the 1918 flu strain that killed millions, but fortunately not all of those changes. In fact, the wild bird strain derived from Qinghai Lake in western China has been found to not carry certain resistance markers. This means it should be sensitive to both amantadine and rimantadine, two of the few drugs available to treat bird flu infections in humans. By contrast, the H5N1 strain in Vietnam and Thailand carries those genetic markers so it responds only to oseltamivir (commonly known as Tamiflu).

Whether stockpiles of these drugs will be put up in sufficient amounts and in good time remains to be seen. The WHO has reached an agreement with the Swiss drug giant, Roche, to stockpile at least 30 million capsules of Tamiflu, enough for three million patients in the event of an outbreak. Singapore has stockpiled enough Tamiflu for 430,000 people and continues to acquire more.

Let`s pray all parties concerned will remain vigilant.



Andy Ho is a senior writer of the Straits Times. - Ed.



By Andy Ho