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In the Chinese city of Hong Kong, 10 years ago, a bird flu virus jumped directly from chickens to humans. Eighteen people were infected and six died. That outbreak set off a decade of worry that the next devastating flu pandemic might be brewing. That pandemic has yet to happen, and lately, flu experts are even allowing themselves some hope the threat may be receding. But notice, they say, it may be receding. It's still considered important to track what is happening with bird flu.
And a dispute between rich and poor nations is blocking a vital effort to do that. NPR's Richard Knox reports.
RICHARD KNOX: Human cases of the bird-flu virus called H5N1 are still occurring. Right now, a team from the World Health Organization is investigating what could be the largest cluster of human-to-human transmission so far in Pakistan.
A veterinarian and five members of his family are suspected cases, along with three others involved in culling infected chickens. Such clusters are rare, but they've occurred in Thailand, Vietnam and Indonesia.
Does that mean the world is moving closer to a pandemic? It depends on who you ask. Dr. Anthony Fauci is the U.S. government's top flu researcher.
Dr. ANTHONY FAUCI (Director, National Institute of Allergy and Infectious Diseases in Bethesda, Maryland): There are those who say it's been around for 10 years and it hasn't happened yet. Therefore that just proves how difficult it is for it to happen. Then there's another school of thought that says, hey, you know, it hasn't happened, but why should we keep giving it the chance to happen?
KNOX: Experts worry that if H5N1 keeps circulating in poultry - occasionally infecting humans - the virus could acquire the genetic equipment to transmit efficiently from person to person. That would touch off a pandemic. And since up to 80 percent of people infected with H5N1 have died, it could be as bad as the 1918 pandemic that killed 50 million people. But as 2007 comes to a close, there's actually good news about H5N1.
Here's David Nabarro, the United Nations chief flu coordinator, at a meeting in Washington this month.
Dr. DAVID NABARRO (Chief Flu Coordinator, United Nations): We've got a bit of a plateauing. The number of human cases, which act as a sentinel, has slightly decreased. Human deaths have also decreased. There's a suggestion that the situation is not quite so serious.
KNOX: Still, Nabarro says H5N1 is circulating continuously in six countries. Nowhere is that more worrisome than Indonesia, the world's fourth largest nation. The WHO knows about 115 Indonesians infected by H5N1 so far, more than anywhere else. And Indonesia is where another type of flu trouble has arisen this year.
New international health regulations require countries to share samples of flu viruses. But Indonesia has refused to share new specimens of H5N1 as they arise. Dr. David Heymann is WHO's chief flu strategist.
Dr, DAVID HEYMANN (Chief Flu Strategist, WHO): Well, Indonesia has shared about five different specimens or samples this year and from those specimens, one of them produced a virus.
KNOX: Viruses in the other four samples didn't survive, or not enough were present. Without virus sharing, the WHO and flu researchers around the world have no idea what mutations may be taking place in H5N1 as it circulates among Indonesia's countless chickens and 234 million people.
Heymann says the problem arose a year ago, when Indonesia's president asked the health minister to develop a stockpile of flu vaccine produced from an Indonesian strain of H5N1.
Dr. HEYMANN: When the minister went to procure that vaccine, she found that the price that was being asked of her was the same price that was being asked in industrialized countries. And she felt that this was an injustice.
KNOX: Until rich countries guarantee Indonesia a discount on vaccines produced from its viruses, it won't share virus samples. The U.N.'s Nabarro says he understands Indonesia's position. He also sees why Indonesia and other developing countries don't want to rely on promises that they'll get their fair share of vaccines.
Nabarro says they worry that when a pandemic comes, the rich countries will say…
Dr. NABARRO: Sorry, we need all the spare vaccine that's around the place for our people. We're going to have very little to spare for you poorer countries.
KNOX: Untangling that knot is one of WHO's top priorities for 2008.
Richard Knox, NPR News.