JAKARTA, Indonesia (AP) – The World Health Organization has detailed the first evidence that a person likely caught the bird flu virus from a human, then passed a slightly mutated version to another person. But experts said Friday the genetic change does not increase the threat of a pandemic.

The investigation said the mutation of the H5N1 strain of the virus occurred in a 10-year-old Indonesian boy who was part of the largest cluster ever reported. The index case is believed to have been infected by poultry. She then likely passed it to the boy and five other blood relatives. The boy is then thought to have infected his father, whose samples showed the same mutation, according to the report obtained by The Associated Press.

Only one infected family member survived.

“It stopped. It was dead end at that point,” said Tim Uyeki, an epidemiologist from the U.S. Centers for Disease Control and Prevention.

Uyeki, who was part of the investigating team, stressed that viruses are always slightly changing, and there was no reason for this mutation to raise alarm because the virus has not developed the ability to spread easily among people.

U.N. bird flu chief David Nabarro said the findings nevertheless emphasized the importance of continuous monitoring of the H5N1 virus in both humans and poultry.

“We were fortunate in that the change that took place did not result in sustained human-to-human transmission,” he said by telephone Friday. “This is a vivid reminder of the need to keep a very close watch on what the virus is doing.”

Experts fear the H5N1 virus could eventually mutate into a highly contagious form that spreads easily among people, potentially sparking a global pandemic. The current virus remains hard for people to catch, and most human cases have been traced to contact with sick birds. Scientists believe limited human-to-human transmission has occurred in a handful of other clusters, all of which involved very close contact.

The WHO report was distributed during a three-day meeting in Jakarta attended by some of the world’s top bird flu experts. Indonesian officials called the closed-door session to ask for help in coping with the virus, which has infected more people in Indonesia this year than anywhere else – killing an average of one person every 2 ½ days last month.

Keiji Fukuda, WHO’s coordinator for the Global Influenza Program in Geneva, said the cluster in Indonesia last month drew international attention because of its size. Otherwise, he said, it resembles family clusters observed elsewhere.

“What we’re really looking for is the kind of human-to-human transmission which can cause large neighborhood outbreaks and big community outbreaks,” he said. The virus in Sumatra island did not spread beyond the eight blood relatives – no spouses were infected.

William Schaffner, a bird flu expert at the Vanderbilt University, called the mutation “noteworthy but not worrisome.” Generally it takes a series of mutations in a bird flu virus to increase the danger of a pandemic in humans, he said by telephone.

Schaffner said it is remarkable that scientists were able to discover a mutation that occurred in a remote village. That’s the result of intense surveillance linked with “21st-century laboratory virology,” he said.

At the end of the meeting Friday, Indonesia’s Welfare Minister Aburizal Bakrie reiterated that the government needs $900 million over the next three years to fight bird flu, which is entrenched in poultry stocks across the archipelago of 220 million people.

“Human cases and clusters are expected to continue to occur in Indonesia as long as avian influenza in poultry persists,” said Bayu Krisnamurthi, Indonesia’s national bird flu coordinator.

The virus has killed at least 130 people worldwide since it began ravaging Asian poultry stocks in late 2003. Indonesia has counted 39 deaths and trails only Vietnam, where 42 people have died.

WHO and others continue to investigate a report that a Beijing man originally thought to have SARS actually died of bird flu in November 2003 – two years before the Chinese reported any human H5N1 flu infections from the mainland.

Eight Beijing scientists detailed the case in Thursday’s New England Journal of Medicine. At the last minute, the journal received a phone call and e-mails purporting to be from the scientists asking to have the report withdrawn, but it had already been printed.

On Friday, journal editors said a man claiming to be the lead author called to say he had not asked for the report to be pulled and that he stood by its claims. The journal alerted reporters and asked the scientist to send a letter signed by all the researchers affirming the report.