Additional Spread of Bird Flu in Southern Vietnam
Recombinomics Commentary
February 23, 2005
>> As of Monday, Dong Nai and Tien Giang in the south are the latest provinces to report no sick birds for 21 days.
The department also said 27 additional areas afflicted by bird flu were found on the same day, mainly in the south.
Over 13,000 birds were culled, most of them ducks and geese.<<
Although the number of provinces declared bird flu free is rising, the large number of additional areas in the south that have new outbreaks are cause for concern. Vietnam has had 3 outbreaks in the past year. The current outbreak is the first of new flu season, which can bring in additional sequences via migrating birds.
Genetic shifting has been noted, and this season the case fatality rate has been 100% in the south. There have also been comments made about the disease become complex, both in Vietnam and Cambodia. This may signal patients H5N1 positive patients with a different clinical presentation, as described last week for three confirmed or suspect H5N1 patients who did not initially present as respiratory cases.
The presence of high concentrations of H5N1 in asymptomatic ducks creates situations which are difficult to control. Most of the recent culling has been of ducks and geese.
Large numbers of asymptomatic ducks infected with deadly H5N1 offer additional opportunities for recombination, which could generate a very lethal H5N1 that transmits more efficiently from human-to-human.
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