International animal health experts and health officers are meeting in Vietnam to prepare emergency plans for controlling the avian influenza virus that has killed 13 people since re-emerging in December. The experts are looking at ways to prevent the spread of the disease from spiraling out of control.

The possible nightmare scenario laid out to officials is devastating. Millions of people dead, commerce and transportation crippled by mass illness on a scale not seen since the deadly Spanish flu pandemic after World War I.

But health experts gathered in Ho Chi Minh City were told this vision of the future does not have to become reality if governments act fast to control the spread of the H5N1 avian flu.

During the past 14 months, the H5N1 virus has killed at least 45 people from Vietnam, Thailand, and Cambodia - 13 of them since December.

Experts from the United Nations and other agencies gathered in Vietnam this week say the risk that the avian flu could sweep the world is grave. But they say, there is hope the virus can be contained, because it has not yet adapted enough to pass easily among people - almost all human victims have caught it from poultry.

The World Health Organization agrees that the best chance of stopping the virus lies with shifting the focus from the human threat and back to the source of the disease - poultry. Every time the disease jumps from bird to humans it has one more chance to mutate into an airborne human-to-human virus. So health officials say the most obvious plan is to limit public contact with poultry.

The squawking of ducks just before slaughter is never a happy one for the ducks, but it is music to the ears of international officials touring one of Vietnam's first modern slaughterhouses in Ho Chi Minh City.

Almost all chickens and ducks in Vietnam are killed by hand in open-air markets in front of customers - a health hazard since blood is one of the major carriers of the virus. So late last year, Ho Chi Minh City set up 47 modern slaughterhouses and banned live chicken and duck markets.

It is one of many steps that need to be taken to control the avian flu.

Joseph Domenech of the U.N. Food and Agriculture Organization says that keeping the virus from jumping from poultry to humans is a more realistic strategy than trying to eradicate it altogether.

"Controlling the disease, this is something that can be done today because the tools exist," he said. "We know the tools, the governments have applied the tools, have achieved a lot of improvement of the situation. Yes, it is possible with more investment to achieve good results in terms of controlling the effect of the disease. Eradication - it is another matter, which will be very difficult."

But containing the avian flu will be a challenge - especially in countries such as Vietnam, where up to 90 percent of chickens in the country are raised in family yards with children playing there.

Overhauling the country's 40 million small chicken farms will cost millions of dollars and there is no plan for how to do it. Coming up with a plan - and a budget to present to donor governments - is the goal of this week's conference.