By Devika Dixit, MD

It's a site designed to help consumers decide where to eat. Now, New York City health officials may have found a new use for the popular restaurant review site Yelp: spotting foodborne disease outbreaks.

The New York City Department of Health and Mental Hygiene (DOHMH) teamed up with Yelp and Columbia University researchers to comb through nearly 300,000 Yelp reviews of the city's restaurants. They then whittled the list down to 468 reviews that suggested experiences consistent with a foodborne illness, and found that only 3 percent of them had ever been reported to the NYC Department of Health.

The researchers subsequently interviewed 27 of the reviewers. From these interviews, they identified previously unknown and unreported disease outbreaks at three restaurants, which accounted for 16 illnesses. Further investigation into two of the three restaurants identified multiple violations including mouse activity, live roaches and improperly sanitized work surfaces.

Dr. Sharon Balter, an author of the report published Thursday by the U.S. Centers for Disease Control and Prevention, said that the idea of using Yelp to track potential outbreaks came from a member of her team, who was a fan of the site.

"[We thought], 'Wow if we could sort through all these Yelp posts, when we found groups of postings where groups of people got sick… it could help us identify an outbreak," she said.

The fact that the strategy worked to actually identify outbreaks, Balter said holds possible promise for future investigations.

"We didn't really know what we would find, but we were really excited that we found three outbreaks," she said, adding that in the future her team will "try to broaden it by using other social media sites."

Dr. William Schaffner, chair of preventive medicine at Vanderbilt University, said the approach was intriguing.

"My hat is off to the folks at DOHMH for pursuing it," said Schaffner, who was not involved with the study. "It is innovative, and different public health agencies should try to do these experiments to see how we can integrate social media with public health."

"This will be an article that will be read by all of us in public health," Schaffner added, but he cautioned that uncovering true outbreaks in a sea of social media comments could be a challenge. "Even among those who expressed a concern.. there was still a further profound reduction when they got to the actual number of outbreaks," he said.

Doctor's Take

This isn't the first time social media has helped track disease outbreaks. Consider, for example, Google Flu trends.

But for the average restaurant-goer, it might be hard to tell whether an online grouse about getting a foodborne bug at a given restaurant is legit, and sites like Yelp might not be the best places to report such complaints.

For now, Balter noted, consumers should be aware that there are other resources available to the general public to report suspected cases of food poisoning.

"A consumer should know that he or she does not have to post on a restaurant website," Balter said. "They can always call 311."

Still, Schaffner said many consumers are likely to heed negative Yelp reviews, especially where illness is concerned, since most people would prefer to be safe than sorry.

"That is a normal human reaction," he said.