Last September, Food Safety News reported on Yelp’s efforts to start posting health grades on its restaurant pages. Now health officials are experimenting with using Yelp reviews to track down foodborne illness outbreaks. While investigating a recent outbreak, the New York City Department of Health and Mental Hygiene (DOHMH) noticed that diners had reported illnesses on the restaurant review site at The department then collaborated with Yelp and Columbia University to create a program for identifying incidents of illness from those reviews. The team developed a software program to look for keywords such as “sick” and “diarrhea,” two or more people sick, and an incubation period of 10 hours or more. Between July 1, 2012, and March 31, 2013, the program picked out nearly 900 reviews for further evaluation. Epidemiologists subsequently identified 468 events consistent with foodborne illness that had occurred within four weeks of the review being posted. “Only 3% of the illnesses referred to … had also been reported directly to DOHMH via telephone and online systems during the same period,” states the study published last week in the U.S. Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report. The project led to interviews with 27 Yelp reviewers (102 didn’t accept the interviewer’s request) and, in turn, the health department identified three previously unreported outbreaks. The first outbreak in December 2012 was likely linked to salad, the second (in January 2013) was likely linked to shrimp and lobster cannelloni, and the third (in March 2013) was likely linked to macaroni and cheese spring rolls. Environmental investigations were conducted at two of the three restaurants in the week after the interviews, and a routine DOHMH inspection had already occurred at the third restaurant two days after the meal. All of the inspections found multiple violations at each of the outbreak restaurants. DOHMH will continue to develop the project, shortening the time between review and investigation, including additional review websites, and offering reviewers a link to an electronic survey. Chicago is also using social media to track the incidence of foodborne illness. The Chicago Department of Public Health recently teamed up with the Smart Chicago Collaborative to develop a system to contact people who posted about foodborne illness either on Twitter or on the Foodborne Chicago website. The program debuted in March 2013 and, since then, the system has identified 2,918 tweets suggesting foodborne illness. Health officials have replied to 324 of them, and 280 reports have been generated through the Foodborne Chicago website. DNAinfo reports that the program has generated “an additional 150 restaurant and food-service inspections” and prompted 174 investigations in its first year. CDC estimates that 48 million illnesses, 128,000 hospitalizations and 3,000 deaths are linked to foodborne illness annually, but they are vastly underreported. According to CDC’s Foodborne Diseases Active Surveillance Network (FoodNet), there were a total of 19,056 infections, 4,200 hospitalizations and 80 deaths reported in 2013. “As social media usage continues to grow among U.S. adults, health departments might consider additional surveillance methods to capture illness reports from those more likely to post a restaurant review online than to contact a health department,” the CDC study suggests.