No, reviewers aren’t going to film twelve-second clips of themselves barfing. We hope. It’s possible, though, that people might mention illness in their reviews, even if they don’t go to the effort of calling their doctor or contacting the health department.
New York City’s Department of Health and Mental Hygiene worked with Yelp to obtain weekly data dumps of all eatery reviews in the city, then scanned those reviews for words that you might use when reviewing a place that made you ill. Keywords that they looked for included “sick,” “vomit,” “diarrhea,” and “food poisoning.”
500 reviews mentioned food poisoning that turned out to be an actual illness, and health department workers followed up with those customers. Out of the Yelp data dump, researchers found three outbreaks that had previously gone unreported, which sickened a total of 16 people. For smaller incidents where only one or two people reported that they became ill, researchers found that very few of these incidents had already been reported to the health department, and they would need to get the word out about how city residents and visitors can do that.
When you hesitate to mention that you became sick in your online review, reconsider! You might be warning other diners and helping solve public-health problems.
Yelp Helps NYC Health Department Track Foodborne Illnesses [National Geographic]
Using Online Reviews by Restaurant Patrons to Identify Unreported Cases of Foodborne Illness — New York City, 2012–2013 [CDC]