9/12/2005

S. China: perfect incubator for bird flu pandemic? - Yahoo! News

GUANGZHOU, China (Reuters) - The little boy jumped on a crate of clucking chickens as his father called out to him to transfer more birds from a large enclosure into the crate.
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In this dank, poultry wholesale market in Guangzhou in southern China, a woman in the next stall selling ducks chomped on an apple while five bare-chested men sat down to lunch.

All around the humans are cages of live chickens, ducks, geese, rabbits, goats, pigeons and pheasants -- the perfect setting for the H5N1 bird flu virus to mix with other viruses or mutate into what experts predict would be the next pandemic strain.

Once the hybrid is easily transmissible among people -- which experts say will ultimately happen as the virus changes -- they predict more than 25 million hospital admissions and up to 7 million deaths globally within a short period.

At least two of the three pandemics in the last century originated in southern China. And it seems more than a coincidence that the H5N1 made its first known jump to humans in 1997 in Hong Kong, which lies in southern China.

So why is this region such a hotbed for new deadly bugs?

"A large proportion of the global population is in this region, and beyond that there is a diversity of animals that are thought to be important in the generation of these pandemic viruses," Malik Peiris, a microbiologist at the University of Hong Kong who has worked extensively on the H5N1 virus and
SARS, said in an interview.

"These include waterfowl, particularly ducks which are reared in large numbers in this region, pigs and the fact that poultry, pigs and humans are present in very large numbers and in very close proximity to each other in this region. Not just China but southeast Asia," said Peiris .

PERFECT BREEDING GROUND

Spread across Guangdong province in southern China are tiny farms, where villagers raise small numbers of pigs in open sheds. Outside, chickens and ducks are free to roam.

"In places where you have pigs, birds and humans living close to each other, they create the ecology for the emergence of new strains. In southern China, you can easily see them keeping chickens, water birds very close to pigs and humans. This environment makes gene reassortment more likely," said Paul Chan, a microbiologist at the Chinese University.

Gene reassortment is the closest things viruses have to sex. They can swap genes with other viruses, often allowing them to acquire vastly new abilities overnight.

It is a faster way to change than simple mutation-- which could also lead to a new H5N1 strain deadlier to people.

The H5N1 strain has haunted the world since it made its debut in humans in 1997. It is now endemic in parts of Asia, where it has killed more than 60 people since late 2003.

The crisis deepened this year when wild migratory birds began dying from it in central China and experts have since warned that species which survive could carry the virus all over Europe and Africa within the next two migrating seasons.

So far, the virus has been detected in regions north of China in Kazakhstan, Russia and Mongolia. It has also been found in China's southwestern regions of Xinjiang and Tibet, which hangs just over Nepal and the rest of the Indian subcontinent.

But such worries cannot be farther from the minds of farmers and poultry vendors in southern China, where such husbandry practices have been handed down for generations.

"Sick? I have never been sick!" snapped the woman at the market as she carried on eating her apple.

But health experts continue to be alarmed and governments around the world have hammered out contingencies in the event of a pandemic, which is certain to put a stop to all air travel, trade and other aspects of ordinary life.

NEARING THE END?

Chan said the threat of a pandemic has become infinitely larger with the involvement of migratory birds.

"With land birds you can catch and kill them, but with migratory birds you can't. What we fear is that migratory birds will spread the virus to poultry (in other parts of the world). Poultry is closest to humans, that's the tipping point," he said.

"Up until now, transmission from bird to human is not efficient, but with a lot of contact, you will end up with a lot of human cases. When you have a sufficient number of human cases, there is chance for human influenza to mix with avian virus."

"When that time comes, it wouldn't be a pig, but a human mixing vessel (that produces the next pandemic strain). We are far more efficient mixing vessels than pigs. And once H5N1 becomes easily transmissible in humans, it will be the end. We can do nothing to control this spreading."

S. China: perfect incubator for bird flu pandemic? - Yahoo! News

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