As developed nations continue to strengthen their electronic disease surveillance capacities , the parts of the world that are most vulnerable to emerging disease threats still lack essential public health information infrastructure [2,3]. The existing network of traditional surveillance efforts managed by health ministries, public health institutes, multinational agencies, and laboratory and institutional networks has wide gaps in geographic coverage and often suffers from poor and sometimes suppressed information flow across national borders . At the same time, an enormous amount of valuable information about infectious diseases is found in Web-accessible information sources such as discussion sites, disease reporting networks, and news outlets [5,6,7]. These resources can support situational awareness by providing current, highly local information about outbreaks, even from areas relatively invisible to traditional global public health efforts . These data are plagued by a number of potential hazards that must be studied in depth, including false reports (mis- or disinformation) and reporting bias. Yet these data hold tremendous potential to initiate epidemiologic follow-up studies and provide complementary epidemic intelligence context to traditional surveillance sources. This potential is already being realized, as a majority of outbreak verifications currently conducted by the World Health Organization (WHO)'s Global Outbreak Alert and Response Network are triggered by reports from these nontraditional sources [5,6].
- Valuable information about infectious diseases is found in Web-accessible information sources such as discussion forums, mailing lists, government Web sites, and news outlets.
- Web-based electronic information sources can play an important role in early event detection and support situational awareness by providing current, highly local information about outbreaks, even from areas relatively invisible to traditional global public health efforts.
- While these sources are potentially useful, information overload and difficulties in distinguishing “signal from noise” pose substantial barriers to fully utilizing this information.
- HealthMap is a freely accessible, automated real-time system that monitors, organizes, integrates, filters, visualizes, and disseminates online information about emerging diseases.
- The goal of HealthMap is to deliver real-time intelligence on a broad range of emerging infectious diseases for a diverse audience, from public health officials to international travelers.
- Ultimately, the use of news media and other nontraditional sources of surveillance data can facilitate early outbreak detection, increase public awareness of disease outbreaks prior to their formal recognition, and provide an integrated and contextualized view of global health information.
In one of the most frequently cited examples , early indications of the severe acute respiratory syndrome (SARS) outbreak in Guangdong Province, China, came in November 2002 from a Chinese article that alluded to an unusual increase in emergency department visits with acute respiratory illness [9,10]. This was followed by media reports of a respiratory disease among health care workers in February 2003, all captured by the Public Health Agency of Canada's Global Public Health Intelligence Network (GPHIN) [10,11,12]. In parallel, online discussions on the ProMED-mail system referred to an outbreak in Guangzhou, well before official government reports were issued .
These Web-based data sources not only facilitate early outbreak detection, but also support increasing public awareness of disease outbreaks prior to their formal recognition. Through low-cost and real-time Internet data-mining, combined with openly available and user-friendly technologies, both participation in and access to global disease surveillance are no longer limited to the public health community [14,15]. The availability of Web-based news media provides an alternative public health information source in under-resourced areas. However, the myriad diverse sources of infectious disease information across the Web are not structured or organized; public health officials, nongovernmental organizations, and concerned citizens must routinely search and synthesize a continually growing number of disparate sources in order to use this information. With the aim of creating an integrated global view of emerging infections based not only on traditional public health datasets but rather on all available information sources, we developed HealthMap, a freely accessible, automated electronic information system for organizing data on outbreaks according to geography, time, and infectious disease agent  (Figure 1).