The United States' top health official has called for a worldwide surveillance network that could prevent a deadly avian influenza virus from becoming a pandemic. Michael Leavitt, the U.S. secretary of health and human services, was speaking in Vietnam, one of the countries hardest hit by bird flu.

U.S. Health and Human Services Secretary Mike Leavitt responds to a question during a press conference in Hanoi on Friday Oct. 14, 2005

For months, the World Health Organization and others have warned that governments were not taking the potential threat of the H5N1 avian influenza virus seriously enough. But in Vietnam on Friday, U.S. Secretary of Health and Human Services Michael Leavitt, described the threat of bird flu in terms usually reserved for terrorists groups or rogue nations.

"The world is a biologically dangerous place right now," he said. "An enemy avian virus known as H5N1 is establishing a presence in nations all over the world. If it acquires the capacity to co-opt humans as a carrier, it will set off a pandemic struggle that will, or could, end the lives of millions."

As part of a tour of Asia, Mr. Leavitt met Friday with Vietnamese Health Minister Tran Thi Trung Chien on Friday to discuss ways of establishing better surveillance of bird flu cases. He praised Vietnam's efforts in fighting the disease so far. Vietnam has been the country hit hardest by bird flu, with 41 people dead and nearly 50 million poultry either dead from the virus or culled in efforts to halt its spread.

Still, stopping bird flu will require greater cooperation and especially openness between all countries. Secretary Leavitt called for the nations and communities to share information about possible outbreaks quickly and completely. He warned that if a bird flu pandemic breaks out, nowhere will be safe.

"No nation on earth can afford to ignore this," added Mr. Leavitt. "We face a common problem among nations. If there is an outbreak anywhere, there is risk everywhere."

So far, the H5N1 virus affects mostly chickens and ducks but the virus can spread to humans through close contact with infected birds. Some health officials also fear that H5N1, which right now kills nearly half the humans it infects, may eventually adapt to spread easily among people.

Vaccines for the virus are in development, but world capacity for producing vaccine is limited. Mr. Leavitt called Friday for increased production of both vaccines and anti-viral drugs, and said that United States is considering ways to rush medicines to any area where there is a new human outbreak.

"Think of the world as a large forest. If there is a spark in that forest, the forest can catch fire. If someone is there when the spark happens, he can simply put the fire out by smothering it with his foot," he said. "With an avian influenza outbreak, if we can identify it quickly enough and get to the source with speed, it's possible we can very carefully contain it, sparing the rest of the world with its damage."

The United States has promised $25 million to improve global efforts to fight the virus.