for National Geographic News
Scientists have used a sophisticated computer model to predict how a deadly flu virus might spread through the United States, and how the disease might respond to efforts to contain it.
The results suggest that the U.S. is prepared to contain a virus with low transmissibility but perhaps not one that spreads more quickly.
Another team of scientists has also reported that it has developed a preliminary human vaccine against bird flu. But the team acknowledges that more work is needed before the vaccine could successfully contain an outbreak.
Many scientists believe the threat of a bird flu pandemic is real. Researchers are particularly concerned that the virus currently spreading around the worldthe highly pathogenic avian flu strain H5N1might mutate, allowing it to be transmitted between humans.
If such a mutation were to occur, the result could be a global pandemic similar to that of the 1918 "Spanish flu," which killed an estimated 20 to 40 million people worldwide.
"It's still up in the air how readily H5N1 can become human-to-human, but almost certainly there will be another pandemic at some point," said Timothy Germann, a chemical physicist at the Los Alamos National Laboratory in New Mexico.
Germann led the team that developed the computer model.
Christian Sandrock, an infectious-disease expert at the University of California, Davis, said pandemics have historically occurred about every 20 to 30 years.
He said another pandemic is a question of when, not if. The unknown is what the virus will look like. (Read National Geographic magazine's "Tracking the Next Killer Flu.")
"We have no idea what will come out of the gate when it happens," he said.
"Whether it is H5N1 or something totally different is hard to predict."
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