學習與 H5N1 共存 – Les Sims 博士

馬丁博士首頁 論壇 觀鳥、保護、旅行 H5N1 家禽流感和候鳥 學習與 H5N1 共存 – Les Sims 博士

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      Here’s a letter from veterinarian Les Sims, who has extensive field experience with H5N1 in Asia. As he noted in another thread, “I am a veterinarian, not an ornithologist, and have been closely involved with the avian influenza outbreaks in Asia since 1997, while working for the government in Hong Kong (1993-2002) and subsequently as a veterinary consultant working for FAO in China, Mongolia, Viet Nam, North Korea and Thailand.” – compare this experience with most of the H5N1 pundits, yes, me included. [try googling for ‘sims h5n1’]
      Prompted by discovery that a dead magpie robin in Hong Kong had H5N1.
      (With thanks to Dr Sims for allowing me to reproduce the letter here.)

      Learning to live with H5N1 avian influenza

      Once again a single case of infection with H5N1 avian influenza has made the
      headlines….. but is this really front-page news?

      Hong Kong does not exist in a vacuum. It is an integral, albeit small part
      of China, a country in which H5N1 avian influenza viruses still exist. In
      the Mainland, the disease is occurring in poultry at the village level
      without being diagnosed, as demonstrated by recent cases in which disease in
      humans preceded detection in poultry. This is not a reflection on the
      endeavour or competence of the national veterinary authorities but a fact of
      life in poor rural areas where some 50% of the nation’s poultry are reared
      and where there is little or no incentive to report disease. China is
      currently undertaking mass vaccination for poultry, presumably because the
      authorities believe that the risk of infection in poultry is high.

      Hong Kong has done a remarkable job in preventing avian influenza in poultry
      in the past 3 years but is going to have to learn to live with the threat of
      H5N1 avian influenza for many years to come. Highly pathogenic H5N1 viruses
      will not be eradicated from the region until such times as there are major
      changes to the way poultry are reared and marketed or unless the viruses
      change to a less pathogenic form. The former will involve major social
      dislocation, as rearing of scavenging poultry in village households is an
      economic necessity providing cheap, high quality protein to people who can
      least afford to buy it. Such changes will not occur overnight and who will
      pay for such changes? The latter seems unlikely given that the current
      strains of H5N1 virus have now been circulating in the region since 2001.

      Should Hong Kong continue to import live poultry from the Mainland given
      infection is occurring there?

      Hong Kong has been a leader in developing one of the world’s first avian
      influenza-free poultry compartments in which all suppliers are required to
      meet stringent biosecurity and vaccination standards. These reduce the
      likelihood of incursion of virus into farms and, if this does happen,
      prevents the virus from establishing or spreading.

      Stringent testing and
      checks along the length of the supply chain ensure that silent infection
      with viruses is not occurring and that the necessary measures are being
      implemented. This compartmentalised approach to trade in poultry is now
      advocated by the World Organisation for Animal Health (OIE). It is a
      legitimate way of conducting trade in areas where infection or disease may
      still be present outside of a well-defined, infection-free compartment.

      However, the security of this compartment should never be taken for granted
      and recent calls to ensure proper monitoring of its various components are
      reasonable. Everything should be done to ensure that all farms, vehicles,
      cages and markets in this compartment are subject to the same rigorous rules
      and checks. This is why there is a need for a strong veterinary service
      covering farms in both Hong Kong and southern China.

      Risks associated with poultry imports over the lunar New Year only increase
      if there is a breakdown in this compartment. If new farms are used to supply
      additional poultry these must be verified as meeting all requirements.

      This disease-free compartment will need to be maintained regardless of
      whether poultry are sold in markets or are processed at central slaughtering
      plants.

      At present, the public is receiving very mixed messages about avian
      influenza and much of this is occurring because of the hype generated by the
      media and some sectors of the professional community. There is a huge gap in
      the wider community between the perceived and real risk of being infected
      with avian influenza viruses. People in many countries are avoiding
      consumption of cooked poultry through misplaced fears and some are even
      putting off travel to Asia because of perceived risks.

      It is still not widely appreciated that there have been millions of
      exposures of people to infected poultry in Asia yet relatively few cases of
      disease, demonstrating the low level risk of direct spread of avian
      influenza from birds to humans. There is also confusion between this direct
      spread of virus from poultry with the emergence of a pandemic strain, which
      requires evolution of a virus capable of sustained human-to-human transfer.

      The probability of an avian influenza pandemic strain of virus arising in
      Hong Kong is extremely remote but preparations should continue for the
      import of a pandemic strain of influenza virus from elsewhere at some
      unknown time in the future. Such a strain will be introduced by people not
      poultry.

      Dead wild birds positive for highly pathogenic H5N1 avian influenza viruses
      have been found in Hong Kong intermittently in the past and will continue to
      be found. The risk to public health has not increased as a result of
      detection of virus in a wild bird. All it does is to demonstrate why Hong
      Kong’s avian influenza surveillance system is held is such high regard
      internationally and is a timely reminder to the poultry industry to ensure
      that biosecurity, hygiene and vaccination coverage are maintained.

      Detection of a single H5N1-positive oriental magpie robin should not be
      front-page news in a region where H5N1 viruses continue to circulate and
      reconfirms the “celebrity-status” that these viruses have acquired.

      Les Sims
      Asia Pacific Veterinary Information Services Pty Ltd
      PO Box 353
      Manunda
      Queensland 4870
      澳洲

      Post edited by: martin, at: 2006/02/09 13:21

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