State Health Department officials have confirmed noro in about 60 Princeton University students since late January.
Officials are testing about 60 ill students at Rider University in Lawrenceville to see if they have the same bug. Two Rider students have been hospitalized.
Norovirus symptoms include nausea, violent vomiting, diarrhea, and stomach cramping. They usually last up to three days.
Rider University officials are cleaning all dorm bathrooms and buildings because the virus is highly contagious.
No classes are canceled and students are encouraged to wash their hands frequently.
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