Some 4,000 chickens have either died or have been culled in southern Vietnam in a bid to halt the latest outbreak of avian flu, Vietnamese authorities say.
Farms in the Mekong Delta have been disinfected and cordoned off and preventive measures have been boosted to prevent the disease from spreading.
The epidemic reappeared earlier this year killing 32 people across Asia.
Experts have warned of the risk of a world pandemic if bird flu combines with a human flu virus.
No humans are reported to have been infected so far in the latest Vietnamese outbreak.
Farmers in Can Tho City have been urged to disinfect their farms every week, and tests are being carried out at other farms in the area.
A Vietnamese paper, Youth, reported of a few smaller outbreaks in the Hau Giang and An Giang provinces in the southern Mekong Delta.
Earlier this year, some 40m chickens and ducks were destroyed in Vietnam to stop the spread of the disease.
The massive cull had devastating repercussions on the country's poultry industry.
Vietnam declared in October that the situation was under control, after failing to completely stop outbreaks earlier in the year.
United Nations health agencies and the Vietnamese government have announced they are about to create a permanent panel in charge of supervising possible future outbreaks of the epidemic.