BOSTON (AP) -- Boston College said the number of students reporting gastrointestinal symptoms after eating at a Chipotle this weekend has climbed to 80.
On Monday, the school had said 30 students, including members of its men's basketball team, had been sickened.
Chipotle Mexican Grill Inc. closed the restaurant in Boston's Cleveland Circle and said it thinks the illnesses are the result of an isolated incident of norovirus, not a multi-state outbreak of E. coli linked to its restaurants. That outbreak has sickened 52 people in nine states, with the most recent illness starting on November 13.
Boston College says all students who reported symptoms have been tested for both E. Coli and norovirus, and that results will not be available for at least two days.
According to a report from the Boston Inspectional Services department dated Monday, an employee at the Chipotle in Boston was sick while working a shift Thursday.
William Christopher, commissioner of the department, said at a briefing Tuesday that it was not immediately known if the restaurant's management was aware of the employee's symptoms. He said the restaurant's permit to operate has been suspended by the city and a disinfection process has begun.
People can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces, according to the Centers for Disease Control and Prevention. The virus is very contagious and can spread quickly in places such as daycare centers and cruise ships.
Infected workers cause about 70 percent of reported norovirus outbreaks from contaminated food. Each year, norovirus causes 19 to 21 million illnesses.
At a presentation Tuesday for analysts in New York City, Chipotle executives noted the exposure period for the E. coli cases appears to be over. The company has said that it is tightening its food safety procedures, and that some of its local produce suppliers might not be able to meet the new standards.
Executives said the chain may eventually raise prices to make up for its investments in improving food safety standards.
Chipotle Mexican Grill, based in Denver, has more than 1,900 locations, primarily in the U.S. The company has already warned that sales are expected to fall as much as 11 percent at established locations for the fourth quarter as a result of bad publicity from the E. coli cases.
That would mark the first time the sales figure has declined since Chipotle went public in 2006.
In its annual report, Chipotle notes that it may be at a higher risk for outbreaks of food-borne illnesses because of its use of "fresh produce and meats rather than frozen, and our reliance on employees cooking with traditional methods rather than automation."
Chipotle shares fell $15.22, or 2.8 percent, to $536.53 in afternoon trading Tuesday.