Follow The Money To Predict The Spread Of Disease

If you're not familiar with the site Where's George?, you've been missing out. It's been around for ages, and lets people track where their money travels. Basically, people put in the serial numbers on their cash and their location -- and the site tracks where the money goes over time. There is a core group of folks who are extremely into the site, even stamping all of their money with "wheresgeorge.com" stamps to encourage people to visit the site and let them know where their money traveled to. I've visited the site a few times in the past (usually after receiving bills that had been stamped), but mostly thought of it as an amusing, quirky "time waster" website that has managed to survive for quite some time. However, some researchers realized that the data on the site actually could be quite useful, and have used it to create more accurate models of how diseases could spread through the US. I'm not sure if I should be impressed by the ingenuity of the researchers, or worried about what diseases I could get from the money in my wallet.