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Indonesian bird flu cluster may be human-to-human-to-human spread: WHO
http://ca.news.yahoo.com/s/23052006/...an-spread.html
By Helen Branswell
(CP) - The large cluster of human cases of H5N1 avian flu being investigated in Indonesia may represent the first time the virus has been seen to ignite two successive waves of human-to-human spread, the World Health Organization said Tuesday.
A spokesperson said the agency has not yet started the process of reviewing whether the global pandemic alert level should be raised to Phase 4 from the current Phase 3.
But Maria Cheng said it is conceivable that WHO might convene a meeting of the panel of experts who would advise on that decision - depending on what further investigation in the affected area reveals.
"This is the first time we have seen cases that have gone beyond one generation of human-to-human spread," Cheng told The Canadian Press.
"It is an evolving situation and it is possible we would convene the task force if we saw evidence the virus was changing."
According to the WHO's six-level pandemic staging plan, Phase 3 is no human-to-human spread, or only on rare occasions after close contact with a sick individual. Phase 4 is a small cluster or clusters of limited and localized human-to-human spread, a pattern suggesting the virus had not yet become fully efficient at infecting people. Phase 6 is a pandemic.
Cheng noted the pattern of infections in this cluster seems to point away from a substantial change in the transmissibility of the virus. So do the genetic sequences of two viruses retrieved from this group of people. A statement from the WHO said analysis of those viruses showed "no evidence of significant mutations."
But a veteran U.S. infectious diseases expert said he's worried the world may be seeing something different with this group of cases.
"Certainly there've been more cases in this cluster than we've had before," said Dr. D.A. Henderson, of the Center for Biosecurity of University of Pittsburgh Medical Center.
Previous cases of human-to-human transmission of the H5N1 virus are believed to have happened, but it is thought that in those earlier instances the virus died out after one generation of person-to-person spread.
There has been a clear pattern in all these cases: A family member, closely tending someone severely ill with the virus, becomes infected, presumably through exposure to large amounts of virus. And that pattern appears to hold in the Indonesian family cluster, Cheng said.
Henderson, who wasn't so sure, suggested in this case it seems illness has spread beyond caregivers to others in the family. An 18-month-old girl and a 10-year-old boy are among the dead.
"They all had contact, but it was not the kind of contact we've had described before, where the caregiver would be really heavily exposed," he noted.
"And from that standpoint, I find this worrisome. And I think there is an awful lot of information we need about those cases and the circumstances."
Cheng said if new cases began to emerge where people with only passing contact with a case became infected "certainly our level of alarm would increase."
"We haven't seen any evidence that's the case," she added. "So far we haven't identified cases outside this family cluster."
Expert investigators from the WHO and the U.S. Centers for Disease Control believe a woman who died in early May infected some members of her extended family, including a 10-year-old nephew.
During his illness, the boy's father helped nurse the child. The boy died on May 13. Two days later his father started developing symptoms . On May 22, the father died.
Cheng said the current theory is that the index case infected her nephew, who infected his father.
The first case, who died on May 4, was not tested before her burial and is not factored into the WHO's official case count. Investigators in the village of Kubu Sembelang in the Karo district of North Sumatra are watching closely for any evidence the virus is continuing to spread among contacts of the family. Cheng said 33 people are under observation, though she had not heard whether any of them are showing signs of illness.
Some are being given the flu antiviral oseltamivir or Tamiflu. Others were not. Cheng wasn't clear why all the contacts were not taking the drug.
But there have been reports that the rapid and devastating decimation of this family - eight people have become ill, seven have died - has triggered a local crisis of confidence with surviving residents of the village demonstrating fear and hostility to authorities. It was reported, for instance, that the man who died on May 22 refused to take Tamiflu. He fled from the investigators and authorities and lived on the run, sheltered by friends, for the final four days of his life.
"We are still not getting the level of co-operation we would consider optimal," Cheng admitted. Additional WHO personnel are being sent to the village. Included in the group is an expert on social mobilization - the art of gaining local trust and co-operation in the high tension setting of an infectious disease outbreak.
By Helen Branswell
(CP) - The large cluster of human cases of H5N1 avian flu being investigated in Indonesia may represent the first time the virus has been seen to ignite two successive waves of human-to-human spread, the World Health Organization said Tuesday.
A spokesperson said the agency has not yet started the process of reviewing whether the global pandemic alert level should be raised to Phase 4 from the current Phase 3.
But Maria Cheng said it is conceivable that WHO might convene a meeting of the panel of experts who would advise on that decision - depending on what further investigation in the affected area reveals.
"This is the first time we have seen cases that have gone beyond one generation of human-to-human spread," Cheng told The Canadian Press.
"It is an evolving situation and it is possible we would convene the task force if we saw evidence the virus was changing."
According to the WHO's six-level pandemic staging plan, Phase 3 is no human-to-human spread, or only on rare occasions after close contact with a sick individual. Phase 4 is a small cluster or clusters of limited and localized human-to-human spread, a pattern suggesting the virus had not yet become fully efficient at infecting people. Phase 6 is a pandemic.
Cheng noted the pattern of infections in this cluster seems to point away from a substantial change in the transmissibility of the virus. So do the genetic sequences of two viruses retrieved from this group of people. A statement from the WHO said analysis of those viruses showed "no evidence of significant mutations."
But a veteran U.S. infectious diseases expert said he's worried the world may be seeing something different with this group of cases.
"Certainly there've been more cases in this cluster than we've had before," said Dr. D.A. Henderson, of the Center for Biosecurity of University of Pittsburgh Medical Center.
Previous cases of human-to-human transmission of the H5N1 virus are believed to have happened, but it is thought that in those earlier instances the virus died out after one generation of person-to-person spread.
There has been a clear pattern in all these cases: A family member, closely tending someone severely ill with the virus, becomes infected, presumably through exposure to large amounts of virus. And that pattern appears to hold in the Indonesian family cluster, Cheng said.
Henderson, who wasn't so sure, suggested in this case it seems illness has spread beyond caregivers to others in the family. An 18-month-old girl and a 10-year-old boy are among the dead.
"They all had contact, but it was not the kind of contact we've had described before, where the caregiver would be really heavily exposed," he noted.
"And from that standpoint, I find this worrisome. And I think there is an awful lot of information we need about those cases and the circumstances."
Cheng said if new cases began to emerge where people with only passing contact with a case became infected "certainly our level of alarm would increase."
"We haven't seen any evidence that's the case," she added. "So far we haven't identified cases outside this family cluster."
Expert investigators from the WHO and the U.S. Centers for Disease Control believe a woman who died in early May infected some members of her extended family, including a 10-year-old nephew.
During his illness, the boy's father helped nurse the child. The boy died on May 13. Two days later his father started developing symptoms . On May 22, the father died.
Cheng said the current theory is that the index case infected her nephew, who infected his father.
The first case, who died on May 4, was not tested before her burial and is not factored into the WHO's official case count. Investigators in the village of Kubu Sembelang in the Karo district of North Sumatra are watching closely for any evidence the virus is continuing to spread among contacts of the family. Cheng said 33 people are under observation, though she had not heard whether any of them are showing signs of illness.
Some are being given the flu antiviral oseltamivir or Tamiflu. Others were not. Cheng wasn't clear why all the contacts were not taking the drug.
But there have been reports that the rapid and devastating decimation of this family - eight people have become ill, seven have died - has triggered a local crisis of confidence with surviving residents of the village demonstrating fear and hostility to authorities. It was reported, for instance, that the man who died on May 22 refused to take Tamiflu. He fled from the investigators and authorities and lived on the run, sheltered by friends, for the final four days of his life.
"We are still not getting the level of co-operation we would consider optimal," Cheng admitted. Additional WHO personnel are being sent to the village. Included in the group is an expert on social mobilization - the art of gaining local trust and co-operation in the high tension setting of an infectious disease outbreak.
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