Math model can track epidemics in an increasingly connected world

A new mathematical theory on the global spread of epidemics could help identify an outbreak's origin and how it might spread globally, researchers say. A computational model can demonstrate how disease spreads in a strongly connected world where conventional geographic distances are no longer the key variable, scientists working with Northwestern University reported Thursday. To understand this, they said, geographical distance must be replaced with what they have termed "effective distances." "From the perspective of Frankfurt, Germany, other metropolitan areas such as London, New York or Tokyo are effectively not more distant than geographically close German cities such as Bremen, Leipzig or Kiel," said theoretical physicist Dirk Brockmann, who developed the ideas for this research at the Northwestern Institute on Complex Systems. Effective distances can be computed from the traffic intensities in the worldwide air transportation network, the researchers explained. "If the flow of passengers from point A to point B is large, the effective distance is small and vice versa," researcher participant Dirk Helbing of the ETH Zurich university said. "The only thing we had to do was to find the right mathematical formula for this." "With this new theory, we can reconstruct outbreak origins with higher confidence, compute epidemic-spreading speed and forecast when an epidemic wave front is to arrive at any location worldwide," Brockmann said.