Prague, 10 August 2005 (RFE/RL) -- The UN's World Health Organization (WHO) wants to scare you.
But not too much.
Dick Thompson, communicable diseases media officer at WHO headquarters in Geneva, remains low key.
"We've had a few more cases [of bird flu in humans] reported out of Vietnam," Thompson said. "And we've seen press reports of others that may be confirmed soon. There's been some slight spread of the virus in animals in Russia and in other parts of Asia."
The Russian Emergencies Ministry said today that nearly 8,500 birds have died since the virus hit Siberia in mid-July.
Many have occurred near Russia's border with Kazakhstan. That country has also reported the H5N1 virus has been found on its territory.
The UN Food and Agriculture Organization said today that nearly 80 migratory birds have died from bird flu in Mongolia. It is the first time the disease has been reported in that country.
Some doctors and public health experts say that H5N1 disease already has spread among domestic and wildfowl farther and faster and at greater cost than any other such virus ever.
Three conditions could conspire to make this the greatest infectious disease killer in history. The first is that it mutates into a disease that can spread readily from human to human. The second is that it then retains its level of virulence. The third is that the authorities fail to fight it effectively.
The result could be a worldwide pandemic -- an outbreak more severe than any other.
Manila-based Bob Dietz represents the WHO’s Western Pacific region. He told RFE/RL that the UN organization has been struggling with the question of what to say about the disease since early 2004. That’s when the first reports of human deaths began.
"There is so much of this virus spread over such a wide area that we would be irresponsible if we weren’t to start sounding the alarm that indeed, a disease that could pass between people, and that could be very deadly, might evolve from this situation."
"We've been warning people for a long time. But the problem is that the threat has yet to manifest itself," Dietz said. "We have a tremendous amount of virus spread out through Southeast Asia and parts of China now and apparently it's starting to reach into the easternmost parts of Europe."
Alarm bells rang louder as the WHO's knowledge about H5N1 grew. It’s deadly, killing 100 percent of the chickens that it infects. More than half of the humans who have gotten it, evidently from association with birds, have died -- more than 50 people in total.
But how worried should the WHO be?
"It's still basically a theoretical threat," Dietz said.
But Dietz said that the problem, while theoretical, is complicated. H5N1 seems to be constantly changing. It is widening its worldwide reach. It finds other viruses to pair up with. It becomes milder in one form, and startlingly more dangerous in another.
"So it's unstable. It's liable to easily mix with other viruses," Dietz said. "And one of those combinations, one of those changes, could take it to a point where it's much more transmissible between people and could make them ill. Again, [it's] all hypothetical."
Theoretical or not, he said, the health organization is forced to alert the public.
"But there is so much of this virus spread over such a wide area that we would be irresponsible if we weren’t to start sounding the alarm that indeed, a disease that could pass between people, and that could be very deadly, might evolve from this situation," Dietz said.
There is hope in this mix of news. Two groups of scientists have studied computer models of virtual flu pandemics. They said this week their findings suggest that a sound combination of medical and public health responses could limit or contain the disease, should it start to break out in full force among humans. Also a vaccine or vaccines are in the works.
But just as the threat is hypothetical, so are the responses. The computer models are forced to rely on many assumptions rather than data. Full production of the vaccines -- a goal still way down the road -- may come too late.