Are all of the currently reported outbreaks in birds equally dangerous for humans?
( 2004-02-02 16:10) (WHO)
No. Outbreaks caused by the
H5N1 strain are presently of the greatest concern for human health.
In assessing risks to human health, it is important to know exactly which
avian virus strains are causing the outbreaks in birds. For example, the
outbreak of avian influenza recently reported in Taiwan, China is caused by the
H5N2 strain, which is not highly pathogenic in birds and has never been known to
cause illness in humans. The outbreak recently announced in Pakistan is caused
by H7 and H9 strains, and not by H5N1.
However, urgent control of all outbreaks of avian influenza in birds - even
when caused by a strain of low pathogenicity - is of utmost importance. Research
has shown that certain avian influenza virus strains, initially of low
pathogenicity, can rapidly mutate (within 6 to 9 months) into a highly
pathogenic strain if allowed to circulate in poultry
populations.
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