Officials from the Boston Public Health Department confirmed this afternoon that the students were sickened by norovirus.
“Clinically speaking, these cases have symptoms that are not consistent with E.coli," Dr. Anita Barry, director of Boston Public Health Commission's Infectious Disease Bureau, said. "They are more typical of norovirus.”
The source of the outbreak is still being investigated.
Chipotle, which has already been dealing with the fallout of a multi-state E.coli outbreak, said that no confirmed cases of E.coli in Boston have been linked to the company.
"We agree with health officials that it is likely a norovirus, which seems very consistent with the pattern here," Chipotle spokesman Chris Arnold told ABC News in a statement today. "It is important to note that noroviruses are very common, in part because they are so easily transmitted (they can spread through person-to-person contact, on surface areas, or through food or drink). According to the CDC, there are approximately 20 million cases a year, making them the leading cause of gastroenteritis in the U.S."
The company's efforts to increase food safety could also affect Chipotle’s local suppliers. Chipotle spokesman Chris Arnold told ABC News that some local suppliers may not be able to keep up with newly-implemented safety measures.
“Given the heightened requirements for produce — chiefly the high resolution testing — we believe that some of our local growers will not meet these enhanced standards,” Arnold told ABC News. “We’ll certainly look to work with suppliers that do, and to help others where we can, but at the moment, we aren’t sure what the local program will look like. What we are sure of is that our commitment to using the very best ingredients we can remains as strong as ever.”
Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, said that since so many people became sick at once, investigators will likely be looking for a common source for the outbreak.
"This strongly suggests a common source and that makes the investigation more pointed and more focused," Schaffner explained.