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Chasing The Flu

<b>Steve Kroft</b> Reports On Battle Against Possible Bird Flu Pandemic

If this year of tsunamis, earthquakes and hurricanes has taught us anything, it's that worst case scenarios do sometimes happen. Now with winter upon us, the latest thing to worry about is the avian flu -- a particularly deadly bird virus that is ravaging the poultry industry in Asia, and has, on rare occasions, infected humans, killing half of its victims.

Fewer than 100 people have died worldwide, yet the World Health Organization calls it the most serious health threat facing the planet, greater than AIDS or tuberculosis. Because humans have no immunity to the virus, and there are no proven drugs or vaccines to stop it, it has the potential to cause an influenza pandemic similar to the one that killed 50 million people in 1918. It may not happen, but billions of dollars are being spent to sequence its genes, track its movement, and slow its progress in what many people believe could be a race against time. 60 Minutes set out for Europe and Asia chasing the flu.

Correspondent Steve Kroft reports.

It's called the H5N1 virus, a primitive piece of genetic material so small it can barely be seen under the most powerful microscopes. Like all flu viruses, it is constantly evolving and every day scientists record the latest changes as it moves silently around the globe in the bellies of birds.

The virus has infected the waterfowl now migrating the flyways over Southeast Asia. This is the front line in the battle against avian flu, where the most cases have been identified and the most people have died.

Ducks and geese have passed it along to domestic poultry, and humans have gotten it from sick birds. So far, the virus can't pass easily from human to human, but a single deadly mutation could change that and trigger the deaths of tens of millions of people.

"Time is the essence," says Dr. Margaret Chan, the World Health Organization's chief of Pandemic Influenza in Geneva. She calls it a warning signal from nature.

"For the first time in history we are seeing a pandemic unfolding in front of our eyes," says Dr. Chan.

No one has more experience with H5N1 than Dr. Chan. She was director of health in Hong Kong when the first outbreak occurred there in 1997.

This is a virus that affects mostly birds and has killed fewer than 100 people. Why does Dr. Chan see it as such a serious health threat?

"We are seeing very worrying signs, the geographical spread of this virus, and it has extended beyond the usual sort of poultry sector. It is infecting cats. It's causing death in tigers, and so on and so forth. Now we are getting all these signals, and we are tracking the changes of the virus," she explains.

"If you look at the disease it causes in human being, [it] is very severe, with a very high fatality rate. More than about half of the people infected die. We have not seen anything quite like it," says Dr. Chan. "And also, this virus causes unprecedented spread in the animal sector. And we have never seen this in the entire history of mankind."

The best minds in health, science and veterinary medicine have been mobilized to try and stop the bird flu before it can become highly contagious in humans.

Nearly 200 million chickens exposed to the virus have already been destroyed, yet, in the last few months the H5N1 virus has spread from Asia into Europe.

Every morning at the World Health Organization's Strategic Health Operations Center, scientists and public health officials gather to go over the latest information and monitor every suspected human infection. They call it the morning prayers. The man in charge is Dr. Mike Ryan.

"Most of these cases represent a situation in which the virus has breached a barrier between animals and humans. And every time it breaches that barrier is a potential opportunity for a pandemic to start. So each and every one of those cases is important and vital for us to understand what's going on," says Dr. Ryan.

There have been several cases in Vietnam and Thailand, where the virus seems to have spread from human to human, but only to close family members and caregivers. Then the transmission stopped.

"What we haven't seen is sustained efficient human to human transmission. We have not seen chains of infection. And of that we're sure. And that's what we need to look out for," says Dr. Ryan.