At least 40 people have gotten sick after eating at La Prima Espresso on Carnegie Mellon University’s campus earlier this week, including two people who worked at the eatery, according to the Allegheny County Health Department.

The outbreak at the eatery, which closed for cleaning today, is believed to have been caused by transmission of a norovirus, a highly contagious virus that can be spread by ingestion, as well as mere contact with an infected surface or person, said Karen Hacker, health department director.

“The question for us now is was it something from the food handling itself,” she said.

There may be more people who were infected but have not reported it to a health agency and are just dealing with the discomforting, but rarely serious symptoms of nausea, vomiting or diarrhea that can last two to three days, Dr. Hacker said. No one is known to have been hospitalized by the illness in this case.

Officials involved in the ongoing investigation by the university, health department and La Prima, believe that the people who got sick may have eaten or come in contact with either the soup or sandwiches served there on Monday or Tuesday.

CMU tried to downplay the outbreak earlier this week, refusing to comment since Wednesday beyond a brief alert posted on its website Wednesday afternoon saying that 15 students had reported getting sick and that La Prima had pulled “certain food items” as a result.

The reason it was asked to do a more thorough cleaning was because it told the county on Thursday that two of La Prima’s employees had gotten sick, too, said Donna Scharding, the health department’s food safety program manager. CMU did not mention that in its alert to campus.