Thursday a World Health Organization official warned Asian governments to be vigilant for bird flu, and said that the recent outbreak in Hong Kong proves that the disease is still active and poses a threat.

World Health Organization Pacific Director Shigeru Omi said that Hong Kong authorities responded well to their recommendations and suspended poultry imports for 21 days, as well as slaughtering 80,000 birds after three chickens that were found dead at a farm Monday tested positive for the H5 virus group. Additional tests will be conducted to see if they had the deadly H5N1 strain.

Omi stressed that the events were an indication that they must remain vigilant, while speaking on the sidelines of a WHO book launch in Malaysia. ''Constant vigilance is the key,'' he said.

Omi moved on to say that the Hong Kong outbreak of the virus was not unexpected and that the virus is still circulating in the world, especially in Asia. Indeed, at least 246 people have died from bird flu all over the world since 2003, according to WHO data.

Twenty countries have registered outbreaks of bird flu during the first nine months of this year, down from 25 countries during the same period in 2007, according to statements by U.N. officials.

Some of them worry that the public has for the most part lost interest because the virus has not mutated into a fearsome strain that could spread easily among people. It is still hard for people to catch, as most human cases involve direct contact with infected birds.