AR-News: (China) bird flu a danger to humans

[cathy goeggel]

      Poultry News
      Deadly bird flu strain may pose increased risk to humans

      by Ann Bagel on 6/30/04 for Meatingplace.com


      China-based researchers studying the deadly H5N1 bird flu strain say
changes in the virus over time make it an increasing threat to humans,
according to a report published in this week's issue of Proceedings of the
National Academy of Sciences.

      The H5N1 strain killed more than 20 people and millions of birds in
Asia so far this year.

      The researchers' work examined samples of the H5N1 virus collected
from ducks, which can carry bird flu without appearing ill, from 1991 to
2002. The study found that over time, the H5N1 viruses acquired
characteristics that made them lethal to mice. For example, samples
collected in 1999-2000 were less dangerous than those from 2001-2002.
Exactly how the viruses evolved with increasing lethality is not clear.

      Humans could be at risk because viruses constantly mutate, which means
this bird flu virus could accumulate enough genetic changes to pass
effectively between humans. Experts also say if bird flu were to combine
with a human flu virus in a person's body, the two viruses could exchange
genes to create a potent, dangerous hybrid.

      Human infections from bird flu remain rare at this point, but groups
like the World Health Organization and the U.S. Centers for Disease Control
and Prevention still consider the possibility of human infections a threat.

      Editor's note: For more information about the evolving threat of bird
flu, see Dr. Robert Webster's commentary,The perfect storm: Why is avian flu
running amuck?, which appears in the upcoming June/July issue of POULTRY
magazine.