South East Asia sets up task force to tackle avian flu
http://www.100md.com
《英国医生杂志》
As outbreaks of the H5N1 strain of avian flu continue to occur in Thailand and Indonesia and the death toll has reached 31 people, agriculture ministers of the 10 member Association of South East Asian Nations have agreed to establish a task force to fight the spread of the disease.
The Thai prime minister, Thaksin Shinawatra, said his government aimed to eradicate avian flu by the end of October, before the onset of winter, but the World Health Organization has dismissed the target as unattainable.
"Although the Vietnamese authorities claim the country has gone 20 days without an outbreak, our view is that in Vietnam and Thailand the virus is there," said Peter Cordingley, spokesman for the WHO抯 western Pacific region. "It may be lying low, but it hasn抰 gone away, and we are sure that there will be more poultry to human transmission. It will take years just to contain it, never mind eliminate it."
The Indonesian government said on 6 October that the strain of H5N1 virus that has re-emerged in the country recently is not infectious to humans, a claim that has been refuted by WHO and microbiologists. Mr Cordingley said, "Our understanding of the lab reports is that there is no suggestion that this Indonesian strain is any less pathogenic than the Vietnam and Thai strain."
According to research published in Nature in July the Thai and Vietnamese strains are the same genotype and lineage (2004;430:209; http://dx.doi.org/doi:10.1038/nature02746). "The Indonesian cluster has developed somewhat separately, and from this you could conclude that the source of introduction of the virus into Thailand and Vietnam was different to Indonesia, but that is in relation to distribution," said a leading microbiologist based in Asia who did not want to be named.
"It does not mean you can conclude at all that the virus there is any less virulent to humans," he said.
"The Indonesian government says there have been no human cases, but we don抰 know if that is because there is not enough surveillance or because the virus there is not as virulent梚t抯 possible but it抯 premature to say that," he added.
So far this year 20 people in Vietnam and 11 in Thailand have died from the H5N1 strain of avian flu.
"What抯 happening in Thailand is that super-surveillance is going on, so what you抮e getting is not necessarily an indication of a more rapid spread of the virus. It may be just picking up what was there already," said Mr Cordingley.
However, each time a human is infected the H5N1 virus has the opportunity to reassort and combine with an existing human flu virus, potentially unleashing a global pandemic for which there would be no vaccine. So far only one case of human to human transmission has been recorded, when a woman in Thailand contracted the disease from her dying daughter, but experts consider this to be an isolated case.
"We haven抰 yet seen significant changes in the virus, but it抯 important to keep getting samples to follow the evolution of the virus and determine if it is changing in such a way that would make the vaccine now under development less effective," said Dick Thompson, a WHO spokesman in Geneva.
"That抯 why we need samples to understand how it抯 evolving. We抮e not getting all the samples we need, and we keep pressing the issue. There have been three global flu pandemics in the last century, and of these two were clearly reassorted avian viruses," said Mr Thompson.
In April this year WHO made available to manufacturers the prototype seed strain for a vaccine for H5N1 avian flu, but only two companies, Aventis Pasteur and Chiron, have made any major progress in developing batches of vaccine for clinical trials.(Hong Kong Jane Parry)
The Thai prime minister, Thaksin Shinawatra, said his government aimed to eradicate avian flu by the end of October, before the onset of winter, but the World Health Organization has dismissed the target as unattainable.
"Although the Vietnamese authorities claim the country has gone 20 days without an outbreak, our view is that in Vietnam and Thailand the virus is there," said Peter Cordingley, spokesman for the WHO抯 western Pacific region. "It may be lying low, but it hasn抰 gone away, and we are sure that there will be more poultry to human transmission. It will take years just to contain it, never mind eliminate it."
The Indonesian government said on 6 October that the strain of H5N1 virus that has re-emerged in the country recently is not infectious to humans, a claim that has been refuted by WHO and microbiologists. Mr Cordingley said, "Our understanding of the lab reports is that there is no suggestion that this Indonesian strain is any less pathogenic than the Vietnam and Thai strain."
According to research published in Nature in July the Thai and Vietnamese strains are the same genotype and lineage (2004;430:209; http://dx.doi.org/doi:10.1038/nature02746). "The Indonesian cluster has developed somewhat separately, and from this you could conclude that the source of introduction of the virus into Thailand and Vietnam was different to Indonesia, but that is in relation to distribution," said a leading microbiologist based in Asia who did not want to be named.
"It does not mean you can conclude at all that the virus there is any less virulent to humans," he said.
"The Indonesian government says there have been no human cases, but we don抰 know if that is because there is not enough surveillance or because the virus there is not as virulent梚t抯 possible but it抯 premature to say that," he added.
So far this year 20 people in Vietnam and 11 in Thailand have died from the H5N1 strain of avian flu.
"What抯 happening in Thailand is that super-surveillance is going on, so what you抮e getting is not necessarily an indication of a more rapid spread of the virus. It may be just picking up what was there already," said Mr Cordingley.
However, each time a human is infected the H5N1 virus has the opportunity to reassort and combine with an existing human flu virus, potentially unleashing a global pandemic for which there would be no vaccine. So far only one case of human to human transmission has been recorded, when a woman in Thailand contracted the disease from her dying daughter, but experts consider this to be an isolated case.
"We haven抰 yet seen significant changes in the virus, but it抯 important to keep getting samples to follow the evolution of the virus and determine if it is changing in such a way that would make the vaccine now under development less effective," said Dick Thompson, a WHO spokesman in Geneva.
"That抯 why we need samples to understand how it抯 evolving. We抮e not getting all the samples we need, and we keep pressing the issue. There have been three global flu pandemics in the last century, and of these two were clearly reassorted avian viruses," said Mr Thompson.
In April this year WHO made available to manufacturers the prototype seed strain for a vaccine for H5N1 avian flu, but only two companies, Aventis Pasteur and Chiron, have made any major progress in developing batches of vaccine for clinical trials.(Hong Kong Jane Parry)