Health experts say the avian flu that has so far largely affected birds in Asia has the potential to infect humans and cause a worldwide pandemic. Two worrying signs the disease is spreading include the recent discovery of avian flu-infected poultry in Russia and detection of the virus in migratory geese in western China.
Avian flu is an infectious disease of birds caused by strains of the influenza virus.
So far, the virus has been found mostly in birds in Asia. But the World Health Organization's Dick Thompson says international health experts are concerned that the avian flu has the potential to become highly infectious and spread to humans around the globe.
"There's no reason to believe that there will not be another pandemic," he said. "What we don't know is, will this particular virus spark the next pandemic?"
Since 1997, more than 100 people have been infected with avian flu. The virus has claimed more than 60 lives in Hong Kong, Vietnam, Thailand, Cambodia and, most recently, in Indonesia. Meantime, authorities in those countries have destroyed millions of birds in an effort to eradicate the disease.
So far, the human death toll has been relatively low. But the director of the National Institute for Allergy and Infectious Disease, Anthony Fauci, points to what has become a source of growing concern.
"The important thing, it has not yet evolved the efficiency of being able to readily jump from bird to human, and very, very inefficiently going from human to human," he explained. "In fact, only two confirmed cases of spread from human to human. But something like a mutation or recombination of viruses or re-assortment of viral genes from one virus to another could lead to a greater efficiency of spread, such that the spread from human to human would be sustained."
Dr. Fauci says there are examples in recent history of the worldwide havoc wrought by pandemic flu.
"We saw that in 1918, with a catastrophic event with what they used to call the Spanish flu, even though that's a misnomer. But it really devastated the globe, in the sense that there were about 20 to 40 million deaths, and about half a million deaths in the United States," he noted.
He adds that international health experts are more concerned about the avian flu now than they were even five years ago because "it's still around."
"It's still infecting chickens. It hasn't been eradicated," he explained. "And even though there are not a lot of cases in humans, as the weeks and months go on, [there is] another case here, another case there. So, it's going in the direction of more cases as opposed to just disappearing. You know, it might happen this year, it might happen next year. We just don't know. But the circumstances are such that invariably, sooner or later, it's going to happen."
This begs the question, then, are countries ready to face what could be a catastrophic flu pandemic? The World Health Organization's (WHO) Mr. Thompson bluntly says no.
"It's safe, very safe, to say that the world is not ready for the next pandemic. Maybe we haven't raised the alarm high enough," he said.
Mr. Thompson adds that finding the virus in poultry in Russia and in migratory birds is worrisome because it shows that it is starting to spread geographically.
"It's already fairly well-established, entrenched in Asia, in places like Vietnam, Cambodia and so on," he added. "It's already there and it's going to be very, very difficult to pry it out of the environment so it's no longer a threat to humans. If this virus then increases its range, then it just makes the control objectives even more complicated."
American health official, Dr. Fauci, says there is a vaccine that has been developed in the United States that has been proven effective against H5N1, the name of the strain that is currently found in Asia.
"Last year, when we first recognized the potential problem of the H5N1, we developed a vaccine that we just started testing in April of this year," he explained. "And we have shown that you can have a dose response curve that induces what you can project would be protective immunity."
But Dr. Fauci adds that although a vaccine does exist, there still will be a problem of producing a large enough amount of it, quickly enough, in order to meet what he anticipates could be overwhelming demand.