The NYC Department of Health and Mental Hygiene (DOHMH) discovered that patrons reported illnesses on a restaurant review website called Yelp that had not been reported to the DOHMH.

The DOHMH partnered with Columbia University and Yelp  to prospectively identify restaurant reviews on Yelp that referred to foodborne illness. A software program analyzed about 294,000 Yelp restaurant reviews between July 1, 2012–March 31, 2013 and found 893 reviews that required further evaluation. Upon review, 499 (56%) of the 893 reviews described an event resembling a foodborne illness (eg, reports of diarrhea or vomiting after their meal).

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Moreover, 468 of those reviews described an illness within 4 weeks of the review or did not provide a time period. The DOHMH had only received 3% of those illnesses via telephone and online systems during the same period.  After further investigation, 27 phone interviews occurred, and 3 previously unreported restaurant-related outbreaks linked to 16 illnesses met the DOHMH outbreak investigation criteria. Additional environmental investigation of the 3 restaurants showed several food-handling violations.

Results from this analysis suggest that online restaurant reviews may help identify unreported outbreaks of foodborne illness and restaurants with inadequate food handling. The DOHMH plans to continue to refine this project.

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