Tracking outbreaks on the Web

They call it "surveillance sans frontieres."

Exhibit A is the SARS outbreak and how information on it spread. The deadly respiratory disease was first suspected from Chinese news stories about a steep rise in emergency department visits. Then media reports of healthcare workers suffering from an acute respiratory ailment were picked up by Canadian global health trackers. At the same time traffic about the outbreak was spiking on the ProMED online disease-reporting network. Chinese government reports lagged far behind these unofficial sources.

With that 2002 outbreak in mind, Children's Hospital Boston informatics experts created a way to distill a variety of information sources on infectious disease outbreaks around the world into one free Web-based system called the HealthMap Project. They tested the approach, which mixes local news media reports, international health bulletins, discussion forums, and government data, and report on its successes and remaining gaps in the open-access journal PLoS Medicine.

"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," John Brownstein and his co-authors write.

HealthMap uses computer programs as well as human analysis to weed out duplicate and misleading reports. Its monitoring is intended to supplement traditional public health information gathering in order to create a more complete picture of disease activity, the authors said. The system mines news stories using Google News, for example, which yields fewer entries in less-developed countries, the same places that tend to bear a greater burden of infectious diseases. So a remaining challenge is to close gaps now affecting large parts of Africa and South America, the authors say, by searching for other information sources such as discussion sites, blogs, and listervs to complement news sources.

The study of HealthMap was funded by grants from the National Library of Medicine, the National Institutes of Health, the Canadian Institutes of Health Research, and Google.org.