Over 23,000 ducks and chickens in Thanh Hoa and about 6,800 ducks in Hanoi had been infected with the influenza A virus subtype H5N6 (A/H5N6), said Nguyen Ngoc Son, head of Hanoi’s Veterinary Department on Monday.

The outbreak was discovered about a week ago among a flock of ducks raised by Nguyen Ngoc Son in Hanoi’s Chuong My District, from where it spread to the flocks of three other families in the area.

Chuong My authorities have since destroyed the ducks, halted the transportation of poultry in and out of the area, and disinfected and vaccinated all poultry in the district, said Son. Those who noticed symptoms such as swelling or lack of appetite among the poultry they raise must report to authorities promptly, he added.

In Thanh Hoa, the infected poultry belonged to 10 families in Nong Cong and Quang Xuong Districts.

This is not Vietnam’s first outbreak of this particular bird flu strain. Last August, Ba Ria-Vung Tau Province killed around 10,500 chickens infected with the H5N6 bird flu virus to try and prevent further outbreaks.

The H5N6 virus is capable of poultry-to-human transmission and is potentially fatal. It spreads through contact with faeces or other bodily fluids from infected poultry.

Earlier this month, the Ministry of Agriculture and Rural Development called on localities nationwide to step up preventive measures against bird flu outbreaks in response to recent reports by the World Organization for Animal Health (OIE) stating outbreaks were discovered in 11 countries and territories this year.

Vietnam has also seen avian flu outbreaks in Quang Ninh Province near Hanoi and Nghe An Province which neighbors Thanh Hoa this year, the ministry noted.

Bird flu has killed at least 65 people in Vietnam since it first occurred in 2003, then one of the highest fatality rates in the world. No human deaths have been reported in the last two years, but occasional outbreaks have led to thousands of birds being killed.