Researchers Concerned over Spread of Asian Bird Flu

Researchers track a bird flu virus across northern Asia that has killed nearly 60 people in Southeast Asia who were infected from poultry. Scientists are worried about the sudden spread of the virus.

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Researchers have been tracking a bird flu virus across northern Asia for the past six months. This isn't an ordinary virus. It's the same one that has killed nearly 60 people in Southeast Asia. They caught it from poultry. Scientists fear the virus, with a slight genetic change, could touch off a global flu pandemic worse than any disease outbreak in nearly 90 years. NPR's Richard Knox reports that experts are worried about the sudden spread of the virus, but they don't know how worried to be.

RICHARD KNOX reporting:

The virus is called H5N1. Since it first showed up nine years ago in a Hong Kong goose, hundreds of millions of chickens have died from it or been put to death to contain outbreaks. Over the past two years, the virus has infected a hundred and twelve people and killed nearly half, most of them in Vietnam. But until this summer, it hadn't been seen outside southern China and Southeast Asia.

Now the virus has popped up nearly 2,000 miles north of Hanoi in a swatch from Kazakhstan to neighboring Siberia, northwest China, Mongolia and Tibet. No human cases are known in the north, but the unexpected spread has got flu researchers very jumpy. Dr. Juan Lubroth is with the United Nations Food and Agriculture Organization.

Dr. JUAN LUBROTH (United Nations Food and Agriculture Organization): We are concerned because we have seen spread into Kazakhstan, Siberia, to the Ural Mountains. We have evidence that there has been migratory waterfowl that have died of the disease, and how did the infection get to them? We don't really know.

KNOX: And this mystery is full of suspense because billions of wild birds are just beginning to leave their breeding grounds for points south.

Dr. LUBROTH: With the migration that will be occurring in the next month, month and a half, we are quite concerned that perhaps there could be an introduction of H5N1 into an Indian subcontinent or even towards the Middle East or Europe.

KNOX: That's why Germany and the Netherlands have ordered their poultry farmers to keep their flocks indoors. Other European countries think that's an overreaction for now. To the uninitiated, it seems obvious that migratory birds picked the virus up from backyard poultry in southern Asia and carried it north. But Lubroth says the clues don't add up yet.

Dr. LUBROTH: Dead birds don't fly. Sick birds probably don't fly, either, since they're weak and will not be able to migrate. We have to look at the healthy birds, the ones that are not dying, to get a better understanding of where the virus is and where the virus is not.

KNOX: That's just what William Karesh of the Wildlife Conservation Society did a few weeks ago. His team studied wild birds, alive and dead, at a lake in Mongolia remote from any poultry farms.

Mr. WILLIAM KARESH (Wildlife Conservation Society): We picked Mongolia because it was right in the middle of those two outbreaks, halfway in between, and we figured the same birds are in Mongolia that in are in both Russia and China.

KNOX: Karesh's group counted 55 species of wild birds on the Mongolian lake, about 6,500 individual birds.

Mr. KARESH: None of the healthy birds so far have turned up to be positive. The live birds don't look like they're positive. And it's only in one dead swan that we actually found the virus.

KNOX: That's only one out of a hundred dead birds. Mongolian researchers identified the virus in two or three other bird carcasses. That's enough to keep Karesh concerned.

Mr. KARESH: I've come back from this recognizing that truly wild birds have been infected, and I think the source has probably been domestic chickens and ducks, and now it's been introduced to the wild bird populations.

KNOX: But the striking thing is that the researchers didn't find the virus in more dead birds and so far in none of 750 apparently healthy ducks, geese, swans and gulls. If migrating birds aren't infected with H5N1, they can't shed the virus, as scientists say, and thus infect other birds.

Mr. KARESH: Until we start to see that some of these wild birds are clearly shedding the virus, I'm not so sure how far it'll get or if it'll just burn itself out.

KNOX: To solve that mystery, scientists need answers to questions such as what species are susceptible, and can some wild birds be infected without getting sick? That is the case with domestic ducks and a recent report in the Journal of Virology shows that the virus can infect mallards, which can pass it on without getting sick themselves. Dr. Keiji Fukuda of the World Health Organization says if researchers have learned anything about H5N1 it's that anything is possible. Fukuda has studied this virus since it first emerged in the late 1990s.

Dr. KEIJI FUKUDA (World Health Organization): I'm hardly ever surprised at anything that this virus can do. It's really a pretty amazing virus, and so if it continues to expand its geographic range, I'm not going to be surprised.

KNOX: In the face of a potential flu pandemic, public health planners can't afford to be surprised. Researchers say they urgently need at least a hundred million dollars to track this virus as it spreads and mutates. So far, they don't have it.

Richard Knox, NPR News.

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