If an extremely virulent infection started in Atlanta and spread thanks to folks traveling by plane, what path would it take to reach Sydney or Madagascar? These videos represent models of imagined airplane-borne epidemics.

Dirk Brockmann, a Professor at the Institute for Theoretical Biology at Humboldt University Berlin, and Dirk Helbing, Chair of Sociology, in particular of Modeling and Simulation, at ETH Zürich, published their paper "The Hidden Geometry of Complex, Network-Driven Contagion Phenomena" in the 13 December 2013 issue of Science. Considering the spread of H1N1 in 2009 and SARS in 2003, Brockmann and Helbing modeled how epidemics might spread through highly connected networks, notably air transit networks. Their models rely on a concept they term "effective distance," which uses how locations are connected rather than their geographic distance to predict the spread of disease. The Brockmann Lab website explains:

It turns out that based on this principle we can define an effective distance related to the traffic that connects places for every pair of nodes in the network. This way we extract all nodes from their geographic embedding and represent them based on effective distance.

The video up top imagines the spread of an infection from Atlanta to air transit hubs around the world, using both a map of the world and a radiating tree structure. Below is a video imagining the spread of an illness from Mexico City:

You can also see imagined outbreaks starting in London and Chicago on the Brockman Lab site, just in time for the December travel season.

A geometric approach to network-driven contagion phenomena [Brockmann Lab] Outbreak! Watch How Quickly An Epidemic Would Spread Across The World [FastCo via Laughing Squid]