The Pennsylvania Department of Health said Friday that it is investigating confirmed and potential cases of mumps at Penn State University.
It did not say how many students have been sick and added that it would release no further information "due to confidentiality reasons."
However, Shelley Haffner, infectious disease manager for the university's health center, said there have been five confirmed cases and 15 more are under investigation. The first case was confirmed Jan. 29. Cases have picked up in the last week.
Mumps is a contagious disease spread through respiratory droplets, Haffner said. It is among the infections covered by the MMR (measles, mumps, rubella) vaccine, which is required in Pennsylvania. The CDC recommends that children get two doses of the vaccine, one at 12 to 15 months and the other before entering school.
Parents can seek exemptions to the vaccine law for medical reasons, religious beliefs or "strong" moral convictions.
Haffner said many of the cases have been in students who had received the required two doses of vaccine. Some did not know whether they had been fully vaccinated, but she said none had requested a waiver from the vaccine requirement.
No vaccine is foolproof, she said. The mumps shot is 88 percent effective.
"We know that the vaccine has been effective," she said. "If people weren't immunized, we would have had a whole lot more cases by now."
The state encouraged students to use especially good hygiene while the virus is circulating. "In light of these confirmed mumps cases, and with spring break fast approaching, it is very important for PSU students to avoid sharing food and drinks with others and to monitor their overall health," said Secretary of Health Karen Murphy. "Students who have been diagnosed with mumps or are experiencing symptoms of the virus should check with PSU Health Services before returning to the State College campus."
Penn State's spring break is March 6 to 10.
Haffner said the university is encouraging students who are not fully immunized to get the shots now. Students with symptoms have been asked to stay off campus. She said many have gone home.
Mumps has also been reported at other colleges in the U.S. Haffner said she was not aware of outbreaks in other Pennsylvania schools.
Symptoms of mumps include swelling and tenderness of the glands just below or in front of the ear or jaw, fever, headache, muscle aches, fatigue and lack of appetite. They occur about two weeks after exposure. Some victims have no symptoms.
Mumps can occasionally cause inflammation of the testicles, brain, tissues covering the brain and ovaries as well as deafness.
Haffner said none of the Penn State students have had serious complications.
Infected people can spread the virus for two to three days before they have symptoms and another five days after, she said.