The May 21, 2009 issue of The New England Journal of Medicine contained a Perspective piece that focused on how public health professionals can harness the Internet for surveillance purposes.

The article’s authors, John S. Brownstein, Ph.D., Clark C. Freifeld, B.S., and Lawrence C. Madoff, M.D., point out early on in the article that the Global Public Health Intelligence Network (GPHIN), a collaborative effort founded by the Public Health Agency of Canada and the World Health Organization (WHO), Salmonella Surveillance Graphwhich uses search queries and news aggregators to retrieve keyword-specific articles from the Internet, was a key element in detecting and monitoring the SARS outbreak in 2002-2003. Since that time, such sites as HealthMap have popped up around the Web. Health Map is a Web application hybrid, or “mashup” that provides real-time monitoring of infectious disease threats worldwide.

Early detection of foodborne illness outbreaks, flu outbreaks, and other public health threats is made possible by monitoring online activity. The authors state that, “An estimated 37 to 52% of Americans seek health-related information on the Internet each year, generally using search engines to find advice on conditions, symptoms, and treatments.” Using its search results, Google Flu Trends is able to track users’ search terms and detect patterns of flu-related keyword searches that may indicate an uptick in illnesses in particular geographic areas. On some level, this information could be helpful to public health officials working to identify flu outbreaks.

The authors utilized data from another product, Google Insights for Search, to examine search data related to the recent Salmonella outbreak traced to contaminated peanut butter. They found:

Using Google Insights for Search, a search-volume reporting tool from Google, we compared the epidemic curve of onset dates for confirmed infections with trends in the volume of Internet searches on related terms in the United States. Search terms included “diarrhea,” “peanut butter,” “food poisoning,” “recall,” and “salmonella,” and search volumes were compared with the corresponding volumes from the previous year. The initial public report of [S]almonella was released on January 7, 2009, triggering an increase in searches for “salmonella,” “recall,” and “peanut butter,” but we saw earlier peaks in searches for “diarrhea,” and “food poisoning.”

Although the search trends and reporting tools mentioned in the article can provide practical information and early detection for outbreaks of any kind, the authors cautioned that, “Information overload, false reports, lack of specificity of signals, and sensitivity to external forces such as media interest may limit the realization of their potential for public health practice and clinical decision making.”

Internet surveillance has been ongoing for some time in the public health arena, but new tools may be the key to better surveillance, earlier detection, and a faster response times that could mean earlier detection and better prevention of widespread outbreaks, whether from foodborne pathogens, flu viruses, or other public health threats. The key to utilizing this information will be finding ways to limit the effects of outside factors, such as media attention, that could impact the usability of these new technologies.