NEW YORK -- Mumps is generally considered a disease of the past, since there has been a vaccine for it for decades. But cases of mumps are on the rise among young adults, even those who got the vaccine as children.

Last month, there was a mumps scare at the National Cheerleaders Association (NCA) All-Star National Championship in Dallas. More than 25,000 participants and coaches were told they may have been exposed to the highly contagious virus after one competitor came down with the mumps. The Texas Department of Health says no related cases have been reported so far.

But at James Madison University in Harrisonburg, Virginia, there have been 24 confirmed cases since January.

Health officials are asking students to get immunized if their vaccinations are not up to date. Even so, most recent outbreaks have been among young, vaccinated adults.

Immunity against mumps from vaccination lasts an average of 27 years CBS News

A report out Wednesday found that immunity against mumps from vaccination lasts an average of 27 years, but a quarter of people lose their protection after only eight years. Children get two doses by the age of six.

The mumps virus causes fever, aches and pains, and puffy cheeks from swollen salivary glands. Though most cases resolve, complications do occur in up to 10 percent of adolescents and adults.

The authors of the study suggest clinical trials be done to see if these mumps outbreaks can be prevented by a booster shot at age 18 or during adulthood. According to the Centers for Disease Control, they're going to consider a routine third dose as more studies are done. For now, they're recommending a third dose in people at increased risk because of an outbreak in their area. If you were born before 1957, you probably had the mumps and are protected.