About 16,000 health workers have been mobilized in southwest China's Guangxi Zhuang Autonomous Region, where China's first bird flu outbreak was found, while scientists are still investigating the exact sources of the deadly viruses.

Though three investigation teams still fail to find any clear evidence of how the avian flu viruses originated, some scientists suspected the migratory birds' droppings might be the cause of the epidemic that had swept Asia.

"We can't rule out such possibilities as the birds' droppings carry many viruses," said Professor Zhou Fang with Guangxi University, who is an expert on birds study with the China Zoological Society.

Only one drop from the migratory birds infected with avian flu viruses could cause mass outbreak, Zhou said.

China confirmed its first case of bird flu on Jan. 27 when mass deaths of ducks were reported in Dingdang Town of Long'an County, some 100 km west of Nanning, the regional capital of Guangxi.

"We still can't set the exact sources of the flu viruses after three medical and quarantine teams were sent to check the ducklings, forage and the raisers in the infected duck farm," said Bi Qiang, an official in charge of bird flu control and prevention in Guangxi when answering questions from 14 reporters of Chinese and overseas media who arrived in Guangxi Wednesday afternoon to probe the bird flu.

It is the first time for China to invite overseas reporters to its bird flu-infected region after the outbreak of the avian influenza since Jan. 27.

"Our investigation teams had found some woods near the infected duck farm in Dingdang Town," Bi said, "many birds are inhabiting there."

With the infected village still being blocked from the outside society, Bi said the autonomous region had already mobilized more than 16,000 health workers to help with vaccination and reporting any bird flu outbreak.

Guangxi had intensified its prevention measures against bird flu across the region, especially in areas bordering Vietnam, Bi said.

Some 14,000 fowls had been slaughtered within a radius of 3 km of the duck farm in Dingdang Town after the bird flu outbreak on Jan. 27 and 199,000 more were killed after the region reported a suspected bird flu case in Nanning on Feb. 7.

All the trading poultry markets had been shut down by local authorities within a radius of 10 km of the infected area in Guangxi, Bi said.

"We have thus far discovered no cases of human infection after close medical monitoring and examinations of those having contact with the sick ducks," he said, adding no new cases of bird flu were reported.

The state compensation for farmers' slaughtered fowls went on smoothly in the region and each poultry would be compensated for 5 to 25 yuan (60 US cents to US$3), he said.

(Xinhua News Agency February 11, 2004)