MADISON, Wis. (AP) -- As many as 30 students at UW-Madison are sick with the norovirus.
Many of the students live in the Sellery dormitory.
Symptoms of norovirus illness usually include nausea, vomiting, diarrhea, and some stomach cramping.
Those affected can also have a low-grade fever, chills, headache, muscle aches and a general sense of tiredness.
Health officials aren't considering it an outbreak because the virus has been contained.
Update (3:45pm): University of Wisconsin officials are working to contain an outbreak of the norovirus.
Forty-five students have come down with symptoms, which include vomiting and diarrhea.
All of the cases occurred in Sellery Hall Dormitory on Johnson Street, which is home to more than one thousand students.
Dr. Sarah Van Orman of University Health Services said, "We had seen the cases start to drop off over the weekend. We saw a few more yesterday, so we think we may have a second wave right now."
Students were told to wash their hands frequently and stop washing dishes and utensils in dorm bathrooms.
Norovirus spreads easily in places where people live in close quarters.
Update (8:15pm): University of Wisconsin students are worried the norovirus is spreading to Greek Row.
University Health officials are only confirming 45 cases in one residence hall.
But a sorority girl says a lot of her sorority sisters are sick with norovirus symptoms.
UW student Kristy Kaminski is felling better now, but says she and several of her sorority sisters were unbelievably sick this past weekend.
"Every five minutes in the bathroom throwing up -- after drinking water -- anything like that," said Kaminski. "So, it was really brutal for about three hours. It was miserable."
She notified the head of the UW greek system to warn fraternity and sorority houses.
"Our house went from 6 to about 30 girls in two days being super sick," Kaminski said. "We've had a couple of girls go home, and then the girls that aren't sick luckily are getting a hotel room for the weekend."
Now, she and her roommates are disinfecting everything. The UW is doing the same in Sellery Hall, where University Health Services confirm norovirus affected 45 students.
"We want students to notify their residence hall staff if somebody does vomit in the restroom, so that we're able to clean appropriately, and all the staff are trained in that," said Dr. Sarah Van Orman, Executive Director of University Health Services.
Doctors say norovirus thrives in places like dormitories, where many people live in close quarters.
"This is a virus that's spread by contact on your hands, and coming into contact with vomit or other body fluids, and then spread to your mouth," said Van Orman.
Doctors say the norovirus only lasts about 24 hours, and most people recover quickly.
Most college aged students, they say, should be just fine. The UW encourages any student with stomach-flu-like symptoms to contact University Health Services to get checked out.