BERKELEY, Calif. >> Health officials at the University of California at Berkeley are investigating a possible outbreak of norovirus at the campus in recent weeks.

KNTV reports that the university’s student health center has confirmed three cases of the virus out of 29 possible cases.

Student health services spokeswoman Kim LaPean says university doctors have not been able to tie the cases to any particular event, location or eating establishment.

Norovirus is a common cause of viral gastroenteritis and there are frequently outbreaks during the winter months, though the virus can be spread all year.

Infections can be caused by eating contaminated food, contact with an infected person or by touching contaminated surfaces, the station reported.

Anyone who is sick has been asked to stay home, avoid contact with others and not to prepare food.