MELISSA BLOCK, Host:
Anxiety about bird flu has gone up a notch in response to the largest cluster of bird flu cases among humans so far. Eight members of an extended family on the Indonesian island of Sumatra have fallen ill and seven of them have died. It's the first time authorities have seen the virus go from one person to another, who's then passed it to a third person. That doesn't mean a pandemic has started, but it's making health experts very jittery.
NPR's Richard Knox has more.
RICHARD KNOX: The World Health Organization says a 37yearold woman who sold vegetables at a village market fell ill, apparently with bird flu. She was buried before authorities could get viral samples. Before she died she infected other family members, including a 10yearold nephew. The boy later passed the virus to his father.
Persontoperson transmission of the Asian bird flu virus has occurred before, but humantohuman infections have been rare among the 218 cases recorded over the past three years and this humantohumantohuman chain of transmission could signal something really ominous. Peter Cordingly is a spokesman for the World Health Organization in Manila.
PETER CORDINGLY: What we're looking out for is any sign of this virus going outside of this family cluster into the general community. That would be very worrying.
KNOX: Worrying because it would signal that the socalled H5N1 virus has acquired the ability to spread among people efficiently like ordinary human flu viruses. But infectious disease experts around the world are taking pains to say don't panic. Dr. Michael Osterholm is a flu watcher at the University of Minnesota.
MICHAEL OSTERHOLM: The first shot heard around the world in terms of an emerging pandemic is likely going to be transmission in individuals other than the immediate family. Other villagers, other farmers, merchants, health care workers, people who may have transported individuals and so far that has not appeared to be the case.
KNOX: There is important reassuring news. Dr. Nancy Cox of the Centers for Disease Control and Prevention says scientists have analyzed five viruses from the Indonesian family.
NANCY COX: What we have found is that there's no indication of any unusual changes in these viruses. There is no evidence for genetic reassortment between human and avian influenza viruses and there are no worrisome changes in the viruses that we can see at the moment.
KNOX: The virus didn't swap genes with a human or animal flu virus and it didn't mutate in any obvious ways. But would scientists know what mutations to look for?
COX: We do know some of the changes that we would be looking for. Of course we don't know in detail precisely which changes might make these viruses highly transmissible from person to person, but we do know that we should be looking around the area of the virus, which attaches to the host cell receptor.
KNOX: That's a loop in the virus's coat that hooks onto cells in people or animals it's trying to infect. Cox says there were no changes in that critical loop. Instead, the Indonesian family's virus looks just like the poultry flu viruses that have been circulating in north Sumatra and that's good.
With such evidence, WHO today decided not to raise its pandemic alert level. If it had, Osterholm says that would have triggered some Western companies to start pulling their employees out of Asia, which he says would have been an overreaction.
Richard Knox, NPR News.
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