Indonesian Agriculture Ministry officials take blood sample from an Australian pelican at Gembira Loka Zoo in Yogyakarta, Indonesia, Tuesday, Sept. 20, 2005.

The Indonesian government has vowed to take "extraordinary" measures to contain a recent outbreak of bird flu that has killed four people and possibly infected several others. The move comes as the World Health Organization (W.H.O.) says a quarter of a billion dollars will be needed in just the next year to keep the flu virus from spreading.

Under Indonesia's new measures, people exhibiting symptoms of bird flu, which include high fever, coughing and difficulty breathing, can be forcibly hospitalized.

The measures are tough, but are in keeping with increasingly strident warnings from the W.H.O. about the need to prepare for a world-wide bird flu outbreak.

At the W.H.O.'s annual conference, being held this week in New Caledonia, the agency's Asia Pacific director, Shigeru Omi, said it would cost $250 million during the next 12 months to prepare for a possible bird flu pandemic in humans.

Margaret Chan, the W.H.O.'s director of infectious diseases surveillance and response, said to prepare for a possible pandemic is costly, but not to prepare would be far more expensive in terms of world-wide deaths from the virus, and the social and economic upheaval that would bring.

The virus in question is called H5N1. The strain is dangerous to human beings, killing at least 57 people in four Southeast Asia countries since late 2003.

Nearly all of the 57 have caught the virus from close contact with infected birds. But the W.H.O. says it has still not found the source of infection for three people, a father and his two daughters, who died from the virus in Jakarta in July.

Georg Petersen, the W.H.O. representative in Indonesia, says the death of a fourth Indonesian from bird flu in August is also still under investigation.

"With the latest lady we found in Jakarta, still I think the investigation is ongoing, there were lots of chickens and ducks in her neighborhood, but as far as I have been told there was no actual chicken deaths among those recently," said Petersen. "But the tests from all those animals, I do not know the results yet," he said.

Health experts warn if the virus mutates to a form that is easily passed from human to human, a lethal pandemic could result.

Mr. Petersen says no country can afford any longer to be complacent about bird flu.

"We need to prepare - every country - for an eventual massive influenza epidemic that puts perhaps up to 30 percent of the workforce in bed," said Petersen. "How do you organize society when a large portion of people are sick or might die? These are things that need to be prepared for," he said.

As the new health measures indicate, Indonesian officials are taking no chances. They closed a popular Jakarta zoo during the weekend after 18 birds there tested positive for the H5N1 virus.