A bird flu pandemic could kill as many as 150million people if the world fails to stop it spreading from human to human, the United Nations has warned.
Dr David Nabarro of the Geneva-based World Health Organization said UN Secretary-General Kofi Annan has asked him to head up a worldwide drive to contain the current bird flu pandemic and prepare for its possible jump to humans.
If the virus spreads among humans, the quality of the world response will determine whether it ends up killing five million or as many as 150 million, Nabarro told a news conference.
The last flu pandemic, which broke out in 1918 at the end of World War One, killed more than 40million people and drove home the vulnerability of a world where borders had less and less meaning, he said.
It seems very likely the H5N1 bird flu virus will soon change into a variant able to be transmitted among humans and it would be a big mistake to ignore that danger, he warned.
"I am almost certain there will be another pandemic soon," Nabarro said.
Some governments and international organizations have already started joining forces to begin preparations.
US President George W Bush unveiled a plan at the United Nations this month under which global resources and expertise would be pooled to fight bird flu, and Washington is hosting a planning meeting in October.
66 deaths so far
So far, the H5N1 virus has mainly infected humans who were in close contact with infected birds and has killed 66 people in four Asian nations since late 2003.
Millions of birds have been destroyed, causing estimated losses of $10billion to $15billion to the poultry industry, with the heaviest losses in Thailand, Vietnam and Indonesia.
The virus has also been found in birds in Russia and Europe.
But once humans have caught it, the virus has shown it has the power to kill one out of every two people it infects.
Asia and the Middle East are particular concerns as the bird flu is now concentrated in Asia and could be carried to the Middle East by migratory flocks, Nabarro said.
But an outbreak in an impoverished and conflict-ridden part of Africa such as Sudan, where health services are scarce and millions have been driven from their homes, could lead to "a nightmare scenario," he said.