This is scientific Americans 60 second science. I'm Karen Hopkins.

If you've ever checked out the restaurant reviews on Yelp, you know that these little

missives can tell you whether a bistro is overpriced or understaffed or just nothing

to write home about. But they may also be able to tell the local health department whether

an establishment has been serving up Salmonella. Researchers at Columbia University in New York City

were looking into an outbreak of food poisoning at a local restaurant a few years ago

when they got the idea of using social media

to track gastrointestinal disturbances.

During the investigation, the Department of Health noted that patrons had reported their illnesses on

Yelp and their reviews, but hadn't reported them to 311, the city's official reporting service.

Computer scientist Thomas Efland, who led the study.

Previous investigations had shown that monitoring social media for keywords associated with illness

was a good way of rapidly identifying outbreaks of infectious diseases, such as the flu.

So Eflind and his team built a similar system for stomach symptoms.

The Department of Health started using it in 2012.

The tool works by sifting through the recent Yale reviews for New York City restaurants each day to identify potential reports of foodborne illness.

Yelp reviews get scanned for tell-tale terms such as vomit, diarrhea, food poisoning, and sick.

Flagged entries then get passed along to epidemiologists for a closer look.

The systems produce some false positives. For example, from reviews that stated things like,

the food had a weird chunky consistency, hopefully we won't get sick tonight.

And also missed a few posts like when the writer misspelled diarrhea

a challenging word to write down even when you don't have it but overall the results are nothing to sneeze at.

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