At least 51 students and employees at Stanford University have been sickened in a suspected norovirus outbreak, according to a spokeswoman for Santa Clara County Public Health. The outbreak appears to have originated in the dining hall of Florence Moore Hall. Students who dine at the hall began complaining of symptoms such as diarrhea, vomiting and nausea beginning Tuesday afternoon. Four students received emergency care for dehydration, including intravenous fluids, but none were checked in to a hospital, according to public health information officer Amy Cornell. Cornell said that university staff would be closing the dining hall after dinner Thursday night to heavily sanitize the facilities in case there is a lingering contamination issue. The county health department has dispatched a team of investigators to determine the source of contamination and identify the pathogen causing the illnesses. Health officials have not yet been able to test a sample from any patients, but Cornell said the infections and were consistent with norovirus. It’s also the beginning of norovirus season, Cornell added, and it’s difficult to completely prevent its spread. The university was notified of the problem early on, thanks to an early warning system it has in place, Cornell said. The university, in turn, was quick to contact the health department. “Stanford has been really great with letting us know as soon as they knew about this,” Cornell said. The story originally broke in Stanford’s student newspaper, The Stanford Daily. County health investigators will continue working to determine the source of the outbreak in the coming days.