California scientists using an Internet game that traces the movement
of dollar bills have created a model for tracking the spread of
infectious diseases.
"We were confident we could learn a lot from the data collected at the
www.wheresgeorge.com bill-tracking Web site, but the results turned out
far beyond our expectations," said Lars Hufnagel, a postdoctoral fellow
at the Kavli Institute for Theoretical Physics at the University of
California-Santa Barbara, and co-author of the study.
Historical pandemics, such as the 14th-century plague, moved
slowly since people could typically only travel a few miles daily. It
took the plague three years to move up the European continent, with an
average rate of spread of about one mile a day.
"But today people move great distances in short time
periods, as well as short distances, and they use variable means of
transportation," said Hufnagel.
At the Web site, participants register a bill of any
denomination and then monitor its geographic circulation. Analyzing
data from the game, the scientists developed a theory that represents a
major breakthrough for mathematical modeling of the spread of
epidemics.