Ten years after a bird flu virus first jumped directly from chickens to humans, killing six people in Hong Kong, a feared pandemic has yet to materialize.
Lately flu experts even have expressed optimism that the threat could be receding. But meanwhile, a dispute between rich and poor nations is blocking a vital effort to track what's happening with the bird flu virus.
Human cases of the bird flu virus, known as H5N1, have continued. In Pakistan, for example, the World Health Organization is investigating what could be the largest cluster of human-to-human transmission so far. 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 have occurred in Thailand, Vietnam and Indonesia.
But it doesn't necessarily mean the world is moving closer to a pandemic, said Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md.
"There are those who say it's been around for 10 years and it hasn't happened yet. Therefore it just proves how difficult it is for it to happen," Fauci said. "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?'"
Experts worry that if H5N1 keeps circulating in poultry — occasionally infecting humans — the virus could mutate into a form easily transmitted from person to person. That would likely touch off a pandemic. 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 is actually good news about H5N1.
"We've got a bit of a plateauing," said David Nabarro, the chief U.N. flu coordinator, at a meeting in Washington, D.C. "The number of human cases, which act as a sentinel, has slightly decreased. Human deaths have also decreased."
"So there's a question that the situation of the H5N1 virus, at least, is not so serious," he said.
Even so, Nabarro said H5N1 is circulating in six countries. Nowhere is that more worrisome than in Indonesia, the world's fourth most populous nation. The WHO knows of 115 Indonesians infected by H5N1 so far, more than anywhere else.
New international health regulations require countries to share samples of flu viruses. But Indonesia initially refused to share new samples of H5N1. Dr. David Heymann, the WHO's assistant director-general of communicable diseases, said the government in Jakarta has shared about five different samples and specimens.
"From those specimens, (only) one of them produced a virus," he said.
Viruses in the other four specimens didn't survive or not enough of them were present. That means 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 said 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.
"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. She felt that that was an injustice," Heymann said.
Until rich countries guarantee Indonesia a discount on vaccines produced from its viruses, it won't share more samples. A year's worth of tense discussions have failed to resolve the impasse.
The U.N.'s Nabarro said he understands Indonesia's position. He also sees why Indonesia and other developing countries do not want to rely on promises that they'll get their fair share of vaccines.
Nabarro said they worry that when a pandemic comes, the rich countries will say, "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."
Resolving the dispute is one of WHO's priorities for 2008.