Georgetown University officials believe that norovirus is the culprit behind the sudden illness that has struck nearly 200 students.

School officials have cancelled several sporting events due both to the highly contagious nature of the norovirus as well as the fact that several student athletes have contracted the stomach bug now spreading through the student population.

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The D.C. Department of Health revealed the diagnosis Friday, saying it was the norovirus and not food poisoning, as first thought, that sent about 170 students to the health center and hospital with stomach pain, vomiting, and diarrhea. Officials say that number doesn't even include sick students who stayed inside their dorms. The wave of illness began Tuesday night, and since it is highly contagious, doctors don't know when it will end.

University officials say they have begun an aggressive approach to cleaning, but still don't know what caused the norovirus outbreak in the first place.

Georgetown student Mark Kavulich notes, "The administration has given us all money on our 'GO Cards' to go do laundry, encouraged us to do clean up place and just are very worried about it, put signs everywhere."

At least those affected now know what they are dealing with. "That's shocking. It's contagious? Okay -- then I am going to have to stay away from all of my friends," said Lauren Gambradello, a student.

Student Andrea Kurkel said, "It was pretty bad. All Wednesday morning I was out all of classes." Her brother plays on the Georgetown pep band, which will be staying home this weekend after the cancellation of a football game against Colgate. "I think it would have been easily spread, especially with them all tackling each other. I'm sure with homecoming there would have been parties."

Norovirus causes the majority of non-bacterial outbreaks of gastroenteritis, an inflammation of the lining membrane of the stomach and the intestines.

One of the reasons so many students are ill is because the norovirus spreads very easily from person-to-person, and once soemone has it there is no treatment or cure. Norovirus is often called "stomach flu," and one usually hears about outbreaks in contained populations living in close quarters like cruise ships and hotels.

Georgetown freshman Sara Levin worries she might get the same thing that's sickened at least 170 of her fellow classmates, even though she admits she is not entirely sure what it is. 

The norovirus affects the stomach and intestines, causing nausea, vomiting, diarrhea and cramps. The symptoms usually come on fast and hard, sometimes within 12 hours of exposure. The virus hits the elderly and young the hardest.

"For most people this is not a major problem; it's a rather common viral infection that's what we call self limiting," said Dr. Pierre Vigilance of the D.C. Dept. Of Health. "Most people get better in one to two days."

The virus is highly contagious: one can get it from food, contact with contaminated common spaces or from direct contact with someone who has it. Officials also say an infected person is contagious for days after the symptoms go away.

Doctors say the best defense is very simple: wash your hands. In fact, doctors hope the hand washing will help end this outbreak because there is no antibiotic that will defend against it, and say it is something sufferers must simply live with until it runs its course. They do say, however, that people who get it should drink plenty of water, as dehydration is the primary serious danger associated with the virus. 

According to an email sent out to students early Thursday from school administrators, additional students were treated by doctors overnight Wednesday, bringing the total to nearly 170 students seen by doctors in the past two days. School officials say this number does not include new students who may have been seen at the university's health center or students who didn't report to a health facility.

Todd Olson, vice president for student affairs, said in an e-mail to the university community Wednesday morning that the students were being treated at Georgetown University Hospital for vomiting and nausea. He says most of the students reported having eaten Tuesday at O'Donovan Dining Hall, known as Leo's.

» Letter from Vice President of Student Affairs

"I was pretty sick. I know my friends were more severely ill than I was," said Kaitlyn Gallagher, a student.

Gallagher and three of her friends had eaten at the university's O'Donovan Dining Hall Tuesday evening and a few hours later they were stricken with symptoms of vomiting and diarrhea.

Overnight, the students showed up at the emergency room and health center, some by ambulance. All are being treated with fluids through an IV and anti-nausea medication.

No one was admitted and less than a dozen are still being treated by doctors. O'Donovan Dining Hall was shutdown overnight and the D.C. Department of Health is now surveying students and inspecting the dining hall and its food in an effort to figure out what caused the symptoms.

School officials say students are still getting three meals a day elsewhere on campus, and say they feel the rest of the food on campus is safe, despite an ongoing investigation.

Gallagher and her friends say they all ate different food at the dining hall, and even though she is feeling better, she is still perplexed.

"None of us have any idea what it was," Gallagher said.