posted by admin on 29/05/06
WHO sent mixed signals on whether it might now reassess the disease's threat level.
An unusual cluster of human cases of bird flu in Indonesia has raised the possibility that the virus has for the first time sparked a small human chain of transmission, with the World Health Organization sending mixed signals on whether it might now reassess the disease's threat level.
Officials of the United Nations health agency, together with local authorities, have been monitoring a village in Karo district in northern Sumatra where eight members of an extended family fell ill after a recent gathering. Seven of the eight have died, all but one of whom have tested positive for bird flu. The eighth surviving member also tested positive for bird flu. Authorities haven't found any obvious source of infection in birds in the area -- the usual means by which a human would become infected by avian influenza.
Last week, the WHO said there was no reason to believe that the outbreak has moved beyond the family itself. Such an event might suggest a broad and rapid human-to-human spread of the disease caused by a mutation in the lethal H5N1 strain of the virus that could trigger a pandemic.
After extensive testing in the area, there is no evidence that the outbreak has spread beyond the family that was first infected, and no evidence of any mutation in the virus.
The WHO is faced with the possibility that the virus spread directly from one of the family members to her nephew and then from the nephew to his father. It wouldn't be the first time bird flu may have passed from one human to another, but it would be the first instance of such a secondary, or chain, transmission. In addition, the size of the Indonesian cluster of infections and deaths is unusual.
"What we're dealing with is possibly the first instance of second-generation human-to-human spread," said Maria Cheng, a WHO spokeswoman in Geneva. "But the larger pattern of the virus hasn't changed. It's still people taking care of sick family members who have close and prolonged contact. We're not seeing transmission from people with more casual contact -- that would be a very large trigger for concern."
Ms. Cheng said the WHO is considering convening a group of international experts, such as Nancy Cox from the U.S. Centers for Disease Control and Prevention, to discuss the implications of the latest findings, including whether to raise the group's pandemic alert level.
Keiji Fukuda, acting coordinator of the global influenza program at the WHO in Geneva, later said that while the WHO and local authorities are monitoring the cases, "based on the current situation and assessment WHO is not contemplating convening a group of experts on an imminent basis to decide whether to raise the alert level. Right now, we don't see evidence from the cluster of H5N1 cases in Indonesia to suggest that a phase change should be considered."
The WHO uses a six-level scale to indicate the risk of a human influenza pandemic, or global outbreak. The alert level is at stage three, which indicates that there have been human infections, "but no human-to-human spread, or at most rare instances of spread to a close contact," according to the WHO's guidelines.
Stage four describes a small cluster or clusters "with limited human-to-human transmission but spread is highly localized, suggesting that the virus is not well adapted to humans." On its face, the family cluster in Indonesia could qualify.
Some WHO officials said they are unaware of any discussions about raising the alert.
"To my knowledge, it's not moving in that direction," said Steven Bjorge of the WHO in Jakarta. "I haven't seen any discussion about phase change."
Peter Cordingley, a spokesman for the WHO at its regional headquarters in Manila, added that while officials at the health agency were "very worried," they aren't yet seriously considering raising the alert level. "It's not on the table at this stage," he said in a telephone interview Wednesday afternoon.
Dick Thompson, another spokesman for the WHO in Geneva, was en route Wednesday to Jakarta to help deal with the situation.
There has been significant apprehension within the WHO about raising the alert level. Some officials fear that the public will interpret a shift as a serious alarm, potentially causing panic, even though the difference between the two phases is somewhat subjective and technical.
"We're not sure that the public is going to see that," said Mr. Cordingley. "For them, this will be alarm bells. So we'll have to be very careful about this." Write to Nicholas Zamiska at email@example.com