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Appendix C: The HealthMap System (online only)

Sumiko R. Mekaru, Emily L. Cohn, Colleen M. Nguyen, Clark C. Freifeld, John S. Brownstein


Over the past 17 years, internet technology has become an integral part of public health surveillance. In addition to official infectious disease outbreak information posted online by government agencies, informal online sources, such as blogs and social media, can provide additional information and context in a timely manner. When combined, these diverse sources provide a view of global health quite different from one based solely on 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. As an example, in 2013, increased access to the internet appears to have improved government officials’ acknowledgement of outbreak details during the emergence of avian influenza H7N9 in China.

HealthMap ( aims to create an integrated global view of emerging infectious diseases by using traditional public health reports in conjunction with information from nontraditional, informal surveillance sources, including social media and crowdsourced data. HealthMap is a publicly available online resource that collects, filters, and visualizes disease outbreak reports in real time through a series of automated text-processing algorithms. Sources include online news aggregators (such as Google News and Baidu), expert-curated discussion (such as ProMED-mail), official reports from formal organizations (such as the World Health Organization [WHO] and World Organisation for Animal Health), social media posts from ministries of health, and user-submitted reports. Each week, more than 15,000 reports in 15 languages are classified by disease and location and then mapped to a user-friendly, interactive display (Figure C-1). The languages with the most extensive coverage are English, Spanish, Portuguese, French, Russian, Chinese, Arabic, German, Japanese, and Vietnamese. Reports are collected in a more limited fashion in Korean, Malay, Indonesian, Italian, and Thai; Hindi and Bengali versions are in development.

Public health professionals as well as the general public may submit events not collected by the automated system by using the web interface or 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 (Figure C-2).The application also allows users to search for outbreaks in any location worldwide.

HealthMap serves as a direct information source for more than a million visitors per year, and serves as a resource for clinicians, local health departments, governments, and multinational agencies (such as WHO), which use the HealthMap data stream for day-to-day surveillance activities. CDC and HealthMap collaborate on surveillance projects, including an interactive map of global dengue activity (, developed with CDC’s Division of Vector-Borne Diseases.


The freely available HealthMap site presents users with a customizable map and time series view of worldwide infectious disease alerts. The advanced search feature allows users to control the map view, including the ability to filter by source, date, disease, and location. Registered users can create and save searches, comment on alerts, download data for research, and choose to receive email updates on recent alerts in their area. These registered users may customize their email alerts 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 augments epidemic intelligence with information from outside the traditional public health infrastructure to enhance awareness of disease threats.

Figure C-01. Screenshot of HealthMap

Figure C-01. Screenshot of HealthMap


Figure C-02. Screenshot of Outbreaks Near Me mobile application

Figure C-02. Screenshot of Outbreaks Near Me mobile application



  1. Salathé M, Freifeld CC, Mekaru SR, Tomasulo AF, Brownstein JS. Influenza A (H7N9) and the importance of digital epidemiology. N Engl J Med. 2013 Aug 1;369(5):401-4.
  2. Freifeld CC, Chunara R, Mekaru SR, Chan EH, Kass-Hout T, Ayala Iacucci A, Brownstein JS. Participatory epidemiology: use of mobile phones for community-based health reporting. PLoS Med. 2010 Dec 7;7(12).
  3. 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.
  4. Brownstein JS, Freifeld CC, Reis BY, Mandl KD. Surveillance sans frontieres: internet-based emerging infectious disease intelligence and the HealthMap project. PLoS Med. 2008 Jul 8;5(7):e151.
  5. 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.