Game Helps Predict Spread of Epidemics

Based on an Internet game that tracks the paths of dollar bills, scientists have discovered statistical laws of human travel and developed a mathematical description that could be used to model the spread of infectious disease during an epidemic.

The spread of disease, especially pandemics, is a very serious threat in today's world of intense international travel and trade. The current threat of avian flu is increasing this threat. Historically, pandemics moved slowly, but today they move much more quickly, as shown by the outbreak of severe acute respiratory syndrome (SARS).

The scientists looked at a bill-tracking website on the Internet (www.wheresgeorge.com) and found that human movements follow what are known as universal scaling laws (from local to regional to long-distance scales). Using the game data, they developed a powerful mathematical theory that describes the movements of travelers amazingly well over distances of either a few miles or a few thousand. Their findings were reported in the January 26 issue of Nature.

"Since we can't track people with tracking devices, like we do animals, we needed to get data that provided us with millions of movements of individuals,” explained co-author Lars Hufnagel, a post-doctoral fellow at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara (USA). "What is amazing about these particular scaling laws is the fact that they are determined by two universal parameters only. This result surprised us all.”

"We recognized that the enormous amount of data, as well as the geographical and temporal resolution of bill-tracking allowed us to draws conclusions about the statistical characteristics of human travel, independent of which means of transportation people use,” added co-author Dirk Brockman, a postdoctoral fellow at the Max Plank Institute for Dynamics and Self Organization (Gottingen, Germany).




Related Links:
U. of California, S.B.
Max Plank Institute