Avian flu has so far proved more fizzle than firecracker: It has killed fewer than 150 people, compared with the 35,000 Americans who die yearly from ordinary flu. But the scientific frenzy it sparked is paying off with an array of insights into how the next real epidemic might emerge.
1. New pathogens can incubate slowly, then change rapidly. Sporadic outbreaks of the H5 family of influenza viruses have appeared among birds in Scotland, South Africa, Mexico, and Pennsylvania since the 1950s. Those outbreaks remained localized, however, and triggered few if any human infections. Then the current virus, called H5N1, appeared in 1996 in China. This version was able to spread widely—and this one could kill.
2. Diseases spread in ways researchers don't fully understand. How did H5N1 zoom so quickly across continents? "The short answer is that we don't know enough," says Laurence Gleeson of the United Nations Food ...
