Online Surveillance Tool Tracked H1N1 Virus First

Illustration: HealthMap began picking up informal reports of the influenza outbreak in Mexico as early as 1 April.

Health officials are realizing that informal information sources on the Internet can be a valuable source of up-to-date information for tracking health emergencies such as possible pandemics.

According to researchers from the Informatics Program at Children's Hospital Boston (CHIP), tapping the Internet for information - including news reports, blogs, personal Web searches, chat rooms and social networking sites - is fast becoming a way to get a complete, up-to-the-minute view of public health threats.

This is discussed in a Perspectives article in The New England Journal of Medicine, first published online on May 7, 2009.

In an accompanying sidebar, the researchers describe the use of HealthMap.org - a freely available Web site that aggregates, categorizes, filters and displays real-time information on emerging infectious diseases - in tracking the current H1N1 swine flu outbreak.

HealthMap, they note, first began picking up evidence of the H1N1 flu on April 1, weeks before it began to emerge in the English-language public health literature on April 21.

HealthMap was developed by two of the authors - John Brownstein, PhD, assistant professor at CHIP, and Clark Freifeld, a research software developer at CHIP and a PhD student at the MIT Media Lab. The site mines informal electronic information sources (news reports, curated personal accounts, official alerts, blogs and chat rooms) to search for, track and map infectious disease outbreaks.

"The practice of mining the Internet for public health surveillance purposes has quickly emerged as a valuable way to support and enhance the traditional public health infrastructure," says Freifeld. "News reports in particular can be a valuable resource for information as inherently the media has the ability to saturate towns, cities and communities where public health officials may or may not be present and report on potential disease outbreaks."

Brownstein, Freifeld and their co-author Lawrence Madoff, MD, editor of ProMED-mail, also point to social networking sites like Twitter as tools to offer quick, easy-to-access communications about emerging disease threats.

"Web 2.0 services like Twitter and Facebook are enabling people to become more engaged in public health, which is exciting to see," says Brownstein, "but it will be important that the information provided on these sites is analyzed and used appropriately to ensure its accuracy and that it does not cause unnecessary distress or panic."

According to a news statement, Brownstein and Freifeld set up a HealthMap Twitter feed shortly after the onset of the H1N1 outbreak to distribute relevant news in real-time. In less than a week later, it had over 4,000 followers. And then a day following the outbreak of the virus, the number of unique visitors to the site jumped from 10,000 to as many as 150,000 a day.

Since its founding in 2006, HealthMap has tracked information for a number of other high-profile outbreaks, including jalapeno-related salmonella outbreak in the U.S., the emergence of avian flu across the globe and the deli-meat related listeria outbreak in Canada. And according to the statement, daily users include the World Health Organization, the Centers for Disease Control and Prevention, U.S. Department of Homeland Security, UK Health Protection Agency, the European Center for Disease Prevention and Control, and other public health officials and international travelers.

A copy of the Perspectives piece is available on NEJM.org, which also features an interactive HealthMap page that maps confirmed or suspected cases of the H1N1 virus internationally.