Specimens from UNC tested positive for a
,according to state Public Health Lab reports. Its mode of transmission is still unknown.
Noroviruses are a group of viruses that cause gastroenteritis or the stomach flu in people. A member of that group is the Norwalk virus, which made headlines last year when hundreds of people on several cruise ships got sick.
Noroviruses are usually not serious, but are very contagious and can spread easily from person to person.
People may feel very sick and may vomit many times a day. Most people get better within 24 to 48 hours. However, sometimes people become dehydrated and need special medical attention. Dehydration is most serious for the very young, elderly and those with compromised immune systems.
Both stool and vomit are infectious. People infected with norovirus are contagious from the moment they begin to feel ill to at least three days after recovery. Some people may be contagious for as long as two weeks after recovery. Good hygiene and proper hand washing are critical.
Currently, there is no antiviral medication that works against norovirus and there is no vaccine to prevent infection.
About 20 students were treated over the weekend for the ailment that emerged last week, bringing the total number of reported cases to 300.
Wednesday, officials were able to rule out two organisms that cause food poisoning. They also think the outbreak has pretty much run its course.
The news of the illness -- and questions about its cause -- have spread on UNC's campus, where students have been eager for an answer.
"I don't think it's any new, mysterious illness that has not been described before," said Mary Covington, of the UNC Student Health Service.
Because students got sick all at once, investigators were looking for a common source and waited for additional test results.
"It really will help us a lot if we can figure out what caused it to go back and see if there is anything we can do in the future to prevent it," Covington said.
No one has required hospitalization.