Yelp is a popular service that is used by millions of people around the world to research about venues they might be interested in visiting. Users often post reviews of restaurants they visit and if they don’t like it they can warn other diners. Its up to people how seriously they take a restaurant’s bad reviews but they might not be the only ones reading. Health officials in New York City are using Yelp reviews to trace unreported outbreaks of food poisoning. According to a report released by the Centers for Disease Control and Prevention, New York City’s Department of Health and Mental Hygiene has completed a pilot project in which they used Yelp reviews to track outbreaks.