Norovirus is different from E. coli, the bacteria that led to a widespread illness outbreak stemming from Chipotle restaurants in 14 states two years ago.
The virus is highly contagious and causes symptoms like stomachaches, nausea, diarrhea, and vomiting. It's the most common cause of foodborne illnesses in the US, with about 21 million cases annually.
Cases of norovirus stemming from restaurants can often involve a worker who failed to wash his or her hands after going to the bathroom.
At least 133 people fell ill after eating at the Sterling, Virginia Chipotle that's at the center of the latest outbreak, according to the website iwaspoisoned.com, which allows customers to self-report suspected foodborne illnesses.
Customers reported symptoms such as vomiting, diarrhea, severe stomach pain, dehydration, and nausea after eating at the restaurant.
Chipotle has since reopened the Sterling restaurant after a two-day closure.
"While the restaurant was closed, multiple teams performed complete sanitizations of all surfaces," Chipotle CEO Steve Ells said in a statement Wednesday. "We also provided support to any customers or employees who had reported illness to ensure their well-being."
Chipotle has dealt with norovirus cases in the past. In December 2015, nearly 120 Boston College students fell sick after a norovirus outbreak at a restaurant close to campus.