It’s not a diagnosis we hear often anymore, but a string of college campuses are dealing with an unusually high number of students who’ve come down with the mumps. The latest case is at the University of Maryland at College Park — where one student is confirmed and two others are suspected of having the virus. Health officials are warning all students to protect themselves.

Also hit this year — State University of New York at Buffalo, Indiana University, University of Kentucky, University of San Diego, University of Southern Maine, Saint Anselm College in New Hampshire, and Harvard University, among others.

“The overwhelmingly majority of those infected were fully vaccinated, which was surprising,” said an infectious disease expert.

“College campuses are prime locations for outbreaks of mumps because of the prolonged contact between people living in close quarters,” said Meghan May, Ph.D., an associate professor of microbiology and infectious diseases at the University of New England in Maine.

“The overwhelming majority of those infected were fully vaccinated, which was surprising. What that suggests is that the mumps immunization schedule may not generate lifelong immunity as we assumed, and perhaps we should revisit the recommended schedule,” she told LifeZette.

The year 2016 has seen the most mumps cases in the U.S. since 2010 — and not just on college campuses.

In northwest Arkansas, there were 322 lab-confirmed cases of mumps as of last Friday, according to the Arkansas Department of Health. The viral disease is spreading through 31 schools in three districts there.

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Nearly 40 suspected and confirmed cases of mumps were reported by mid-September in Oklahoma as well, with dozens more cases under investigation. The majority of cases there were found in middle school and high school students.

Through Sept. 10, the Centers for Disease Control and Prevention has reported 1,897 cases throughout 40 states — and it’s not a diagnosis that should be taken lightly.

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Mumps is an acute viral disease characterized by fever, swelling, and tenderness of one or more salivary glands. It is best recognized through painful, puffy cheeks and a swollen jaw, noted the University Health Center at the UMD College Park in a statement to all students. Boys and men may also have painful, swollen testicles. Other symptoms include fever, headache, muscle aches, tiredness, and loss of appetite.

There is no treatment — symptoms usually resolve themselves within a few weeks. And while mumps is usually a mild disease in children, adults may experience it more seriously, and with complications.

 “The more unvaccinated children there are in a community, the more potential patients there are,” said May.

“Mumps has the potential to cause some major complications in rare instances, including deafness, sterility in males, and encephalitis [inflammation of the brain]. While most infected children and adults recover fully, these complications can and do happen,” said May.

Mumps has not been seen much in the United States due to strong vaccination programs. The measles-mumps-rubella (MMR) vaccine protects against mumps — the CDC reports that it’s typically 88 percent effective.

But it can be easily spread when an infected person coughs or sneezes and sends the mumps virus into the air.

And some parents avoid the recommended vaccination schedule for their children. “The more unvaccinated children there are in a community, the more potential patients there are. If there are active cases in communities that also have lower-than-average immunization rates, there is high potential for bigger clusters of cases to occur,” May added.

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Mumps is generally transmitted from about three days before symptoms appear to roughly five days after. However, the virus has been isolated from saliva as early as seven days before, to as late as nine days after the onset of symptoms, according to health officials.

The CDC recommends people don’t share food, drinks, utensils, or other personal items that may contain saliva; that people wash their hands frequently with soap and water, or use an alcohol-based hand rub if soap and water are not available; and that they cover their nose and mouth with a tissue if they sneeze or cough. Otherwise, people with the mumps should stay home and away from public places for five days after the onset of symptoms and limit contact with others in their household.