A new bird flu outbreak has expanded in central Vietnam after it was first detected on a farm in Nghe a province more than a week ago, the government said Sunday.
Nearly 1,300 ducks were found dead late last week in three household farms in Hung Nguyen district, 300 km south of Hanoi, and tests showed they were positive to H5N1, according to a report by the Department of Animal Health of Vietnam.
The dead ducks were part of three flocks that had been not been vaccinated despite Vietnam's aggressive programme to immunize poultry against the virus, the report said.
Earlier this month, more than 70 ducks were found dead in a farm in nearby Dien Chau district and tests on May 3 showed they were positive to the deadly virus H5N1.
Vietnam has so far this year vaccinated 111.5 million ducks and chickens in 60 out of the country's 64 provinces in the first vaccination round of the year, according to the department.
So far, no human cases of bird flu have been reported in the new outbreaks.
Vietnam once had the highest number of human bird flu fatalities at 42 people dead since 2003 - but no human cases have been confirmed since October 2005.
Human infection by H5N1 is still rare, transmitted by close contact with sick birds and not easily passed from person to person.
However, H5N1 has devastated poultry flocks worldwide and has also concerned scientists for its potential to emerge as a new human influenza strain.
International health officials fear that continued contact with humans raises the risk that the virus might adapt to become easily contagious among people. If that happened, it could touch off the first global flu pandemic in decades.
Previous influenza pandemics have killed from 1 million to 40 million people who had no immunity to a new virus strain.