Feb 16, 2016 09:30 AM EST By Russell Westerholm, UniversityHerald Reporter

Ursinus College confirmed norovirus was the cause of a stomach illness that affected more than 200 students last week.

Norovirus is the most common form of viral gastroenteritis among humans and often stems from food contaminated by fecal matter. The outbreak at the private school just 30 miles northwest of Philadelphia was so severe it had to cancel classes Thursday and Friday, according to The Associated Press.

Ursinus reopened Monday, the same day the Montgomery County Health Department confirmed the cause of the quickly spread illness was norovirus. While norovirus often comes from contaminated food, it is highly contagious and spreads through interpersonal contact, making colleges high-risk for outbreaks.

In addition to calling off all classes Thursday and Friday, Ursinus cancelled all its events planned for the weekend. The school said the number of students reporting the stomach illness has decreased since Thursday, The AP noted.

School and county officials do not know the source of the outbreak, CBS' local affiliate noted. Such information, whether it was food-borne, could take up to a week to determine.

"This has been a difficult time for students and their families," Ursinus College President Brock Blomberg said in a statement. "The safety and wellbeing of our students remains our top priority. We are committed to maintaining regular communication with the community and making students aware of all the medical care resources available to them. We are grateful for the outpouring of support we've received from the surrounding community and beyond during this challenging time."

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