A

t least 20 villages in Purbalingga regency, Central Java, have been hit with cases of bird flu, forcing local authorities to remain alert to prevent it from infecting other areas, officials said Thursday.

Purbalingga husbandry office head Hartono said the contagious disease had first been detected in regency in January 2009.

More than 1,000 infected chickens had been culled between January and May by local authorities, he said.

Hartono said his office was collecting data and information on the spread of bird flu this month.

"We are continuing to collect data based on information from local people whose chickens have died suddenly.

"The tests *on those birds* have come back positive for bird flu," he told The Jakarta Post.

The chickens were culled, and their bodies incinerated, he said.

"We don't want to take any risks, and such a *culling method* is based on existing official procedures," he said.

Hartono said most of the virus-infected poultry were domestic chickens that were not kept in cages.

"Because local villagers tradionally have chickens roaming free, not kept in cages, bird flu has spread very quickly," he said.

To curb the virus from spreading further in Purbalingga, the local authorities have set up a special team to combat bird flu.

"The team is already working 24 hours a day. Any time we receive a report on a dead chicken we will go to the location immediately," Hartono said.

The dead chickens, he said, would be used as samples for tests.

Purbalingga has also received 240,000 doses of vaccine from the World Health Organization to help control the spread of bird flu, Hartono said.

"Around 30 percent of the vaccines have already been used."

The WHO has also provided Purbalingga with anti-bird flu disinfectants.