The 24-hour virus hit campus Wednesday, with students falling sick Thursday and Friday, university spokesman Art Petro said.
A dozen students were treated at area hospitals for dehydration, then released. Six faculty and staff members also were sickened, Petro said. The virus is spread person-to-person and virus causes flu-like systems including nausea, vomiting and diarrhea.
Cleaning crews were sent into dormitory bath rooms and dining halls, and the recreation center and pool were shut down for 24 hours for cleaning.
The campus has about 2,200 undergraduate and 1,500 graduate students.