A World Health Organization investigation showed that the H5N1 virus mutated in an Indonesian family cluster on Sumatra island, but bird flu experts insisted Friday it did not increase the possibility of a human pandemic.
The virus that infected eight members of a family last month — killing seven of them — appears to have slightly mutated in a 10-year-old boy, who is suspected of having passed the virus to his father, the WHO investigative report said.
It is the first evidence of possible human-to-human transmission of the H5N1 virus, said Tim Uyeki, an epidemiologist from the U.S. Centers for Disease Control and Prevention. He added that the virus died with the father and did not pass outside the family.
"It stopped. It was dead end at that point," he said, stressing that viruses are always slightly changing and there was no reason to raise alarm bells.
The findings appeared in a report obtained by The Associated Press that was distributed at a closed meeting in Jakarta attended by some of the world's top bird flu experts.
The three-day session that wraps up Friday was convened after Indonesia asked for international help checking the virus, which has killed 39 people there.
Experts fear the virus will mutate into a form that spreads easily among people, potentially starting a pandemic. So far, it remains hard for people to catch, and most human cases have been traced to contact with infected birds.
WHO concluded in its report that human-to-human transmission likely occurred among seven relatives infected with the H5N1 virus in a remote farming village on Sumatra island. An eighth family member who was buried before specimens could be taken is believed to have been infected by poultry, a WHO report said.
Despite the virus' slight mutation in the father and son, Uyeki insisted that an analysis suggested there was "nothing remarkable about these viruses."
Bird flu has killed at least 130 people worldwide since it began ravaging Asian poultry stocks in late 2003.