At least 80 students have fallen ill after eating at Chipotle Mexican Grill, said Boston College in a statement on Tuesday.
"The number of Boston College students who have reported to BC Health Services with GI symptoms has risen to 80 as of noon today. All 80 students have confirmed that they ate at the Chipotle Restaurant in Cleveland Circle (Boston) during the weekend. All have been tested for both E.Coli and the norovirus. Test results will not be available for at least two days," BC wrote.
Chipotle stock last fell 2.9 percent in trade on Tuesday.
Earlier in the day, Chipotle said health officials in Boston believe food-borne illness at one of its Massachusetts locations is likely norovirus. It noted that it appears to be "norovirus isolated to this location" and that it has not heard of reports of illness at any other locations.
On Monday, Chipotle closed the location as officials investigated reports of food-borne illness that sickened some customers, including players on the Boston College basketball team.
So far, the chain says there are no reports of illness from any other restaurants.
In recent weeks, officials have been investigating a multistate outbreak of E. coli linked to the company. To date, 52 cases of E. coli in nine states have been reported.
To prevent food-borne illness from striking in the future, Chipotle is enhancing its food safety measures, using DNA-based tests, end-of-shelf-life testing and additional internal training.
"It's going to cost money," said CFO Jack Hartung. He added increasing its food safety measures is probably going to be inefficient for now.
In its latest annual report, Chipotle explained it may be at a higher risk of food-borne illness than some competitors due to its "use of fresh produce and meats rather than frozen" and "reliance on employees cooking with traditional methods rather than automation."