The farmer reported to the department earlier that 40 chickens were found dead in two sheds in the farm. Twelve swabs were taken from the dead chickens for laboratory testing.

The test result indicated the presence of H5 avian flu virus in two swab samples.

The farm was immediately quarantined and the farmer was not allowed to sell any chickens.

The farmer culled all the 8,300 chickens in the sheds where the dead chickens were found. The department helped to dispose of them in the landfill.

The remaining 32,000 chickens that are housed in other sheds show no symptoms of infection.

The marketable chickens that were last delivered to the Cheung Sha Wan Temporary Wholesale Poultry Market were kept in separate sheds from the ones in which dead chickens were found.

They passed clinical examinations and blood tests before they were sent to the market.

Vaccinations were introduced to the farm on January 8 to control the spread of avian flu.

All young chickens have to be vaccinated twice. The young chickens on the farm were given the first dosage three weeks ago. A booster must be injected 28 days after the first injection to achieve the best effect.

The department stressed that vaccination should not be seen as the only and ultimate solution to tackling avian flu.

The mainstay of measures to deal with the disease should be heightened farm biosecurity, stringent hygienic practices in farms and markets, and an effective surveillance system.