Vials of H1N1 vaccine rest on the labeling collection table at Sanofi Pasteur plant in Swiftwater, Pennsylvania.
Disease tracking is faster and more accurate than ever. Today, Internet bots scour sources around the world in many languages — tapping into public-health advisories, news articles, blog posts and even search-engine queries — to capture trends as they unfold. During last year's flu epidemic, for example, roughly 1 million people used the online tool HealthMap to trace H1N1's global spread.