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Appendix D: The HealthMap System

Amy L. Sonricker Hansen, Clark C. Freifeld, John S. Brownstein


Over the past 15 years, internet technology has become an integral part of public health surveillance. Information about infectious disease outbreaks is disseminated not only through online communications by government agencies but also through informal channels, ranging from media reports to blogs to chat rooms. Collectively, these sources provide a view of global health that is fundamentally different from that of traditional public health infrastructure. Web-based sources provide valuable epidemic intelligence by disseminating current, highly localized information about outbreaks, especially in areas that have limited public health capacity.

HealthMap ( was developed with the aim of creating an integrated global view of emerging infectious diseases, based not only on traditional public health reports but also on a broad range of available information sources, including these informal Internet channels. HealthMap is a publicly available online resource that collects, filters, and visualizes disease outbreak reports in real time, by means of a series of automated text-processing algorithms. Sources include online news through aggregators such as Google News, expert-curated discussion such as ProMED-mail, and validated official reports from organizations such as the World Health Organization (WHO). Disease outbreak reports are collected in 9 languages (Arabic, Chinese, English, French, German, Korean, Portuguese, Russian, and Spanish) classified by disease and location, and then mapped to a user-friendly, interactive display (see Figure D-01).

The system also allows disease experts, public health professionals, and the general public to submit reports of events not collected by the automated system, through both the web interface and by mobile applications ( The “Outbreaks Near Me” mobile application uses GPS technology to show health alerts and ongoing outbreak news in the vicinity of the user. The application also allows users to search for outbreaks in any location worldwide.

Currently, HealthMap serves as a direct information source for over a million visitors per year and serves as a resource for physicians, local health departments, governments, and multinational agencies (such as WHO), which use the HealthMap data stream for day-to-day surveillance activities. CDC has a relationship with HealthMap that includes a specific layer of the map used to geolocate travel-related illness detected by the GeoSentinel Surveillance Network. Also, in collaboration with CDC, HealthMap hosts an interactive map of global dengue activity ( HealthMap extracts data and provides a user interface that is particularly focused on providing users with news of immediate interest, while reducing information overload.


The HealthMap site presents users with a customizable map view of worldwide infectious disease alerts. An advanced search area allows users to control the map view, including the ability to filter by source, date, disease, and region. “Full screen” mode expands the map to cover the full browser window, allowing richer visual display and navigation. The “Local” tab on the HealthMap site automatically detects the location of the user and displays disease alerts within a user-selected radius (see Figure D-02).

Automated e-mail alerts of infectious disease reports are also available from HealthMap. As with the website, users may customize these e-mails to receive only information corresponding to specific parameters, such as diseases, locations, or sources of interest.

Overall, automated surveillance of Internet information sources provides a method for creating a timely, sensitive, and comprehensive view of worldwide emerging infectious diseases. Mining the web is a valuable new approach that plays a useful role in the efforts of public health practitioners and clinicians. Ultimately, HealthMap’s integration of real-time, web-based infectious disease surveillance works to augment epidemic intelligence with information from outside the traditional public health infrastructure to enhance situational awareness of disease threats.

Figure D-01. Screenshot of HealthMap

Figure D-1. Screenshot of HealthMap

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Figure D-02. Screenshot of HealthMap's local page view

Figure D-1. Screenshot of HealthMap


  1. Brownstein JS, Freifeld CC, Madoff LC. Digital disease detection—harnessing the web for public health surveillance. N Engl J Med. 2009 May 21;360(21):2153–5, 7.
  2. Brownstein JS, Freifeld CC, Reis BY, Mandl KD. Surveillance sans frontières: internet-based emerging infectious disease intelligence and the HealthMap project. PLoS Med. 2008 Jul 8;5(7):e151.
  3. Freifeld CC, Mandl KD, Reis BY, Brownstein JS. HealthMap: global infectious disease monitoring through automated classification and visualization of Internet media reports. J Am Med Inform Assoc. 2008 Mar–Apr;15(2):150–7.