From the NEJM:
"The Internet has become a critical medium for clinicians, public health practitioners, and laypeople seeking health information. Data about diseases and outbreaks are disseminated not only through online announcements by government agencies but also through informal channels, ranging from press reports to blogs to chat rooms to analyses of Web searches.
More recently, the advent of openly available news aggregators and visualization tools has spawned a new generation of disease-surveillance "mashups" (Web application hybrids) that can mine, categorize, filter, and visualize online intelligence about epidemics in real time.
The ease of use of blogs, mailing lists, RSS (Really Simple Syndication) feeds, and freely available mapping technology has meant that even an individual expert can create an important global resource."
Digital Disease Detection — Harnessing the Web for Public Health Surveillance. NEJM, Volume 360:2153-2157 May 21, 2009 Number 21.
Influenza A (H1N1) Virus, 2009 — Online Monitoring. NEJM, Volume 360:2156 May 21, 2009 Number 21.
Image in the public domain.