(CNN) - While the U.S. grapples with a measles outbreak unlike any we've seen in decades, Indiana University has a different problem on its hands: mumps.
At least 16 cases have been reported at the Bloomington campus since Feb. 12, IU spokesman Chuck Carney said Thursday.
Nine of those cases have been linked to a single fraternity -- the patients were either members of the fraternity or had visited the fraternity house.
IU is not identifying the fraternity to protect its privacy.
Carney said while mumps outbreaks are unusual at IU, the campus did have another spate of mumps in 2016.
"All of our students are required to have two MMR (measles, mumps and rubella) vaccines by their second semester, with an exemption for religious reasons available," Carney said.
Across the country, measles and mumps cases have surged this year.
2019 has had the second-highest number of measles cases in the U.S. in 25 years, at 555 cases. And the year isn't even half over.
Mumps cases are also on the rise nationwide. The Centers for Disease Control and Prevention reported 426 cases this year as of March 29 -- an increase of 275 cases in one month. Previously, the CDC reported 151 cases of mumps from January to the end of February.
While the two viral infections are similar, there are notable differences.
Measles and mumps are both preventable with MMR vaccines. Patients who get infected with either virus can suffer fever, and, in rare cases, brain damage or death.
But while measles is most commonly associated with a rash that covers the entire body, mumps "is best known for the puffy cheeks and tender, swollen jaw that it causes," the CDC said.
Mumps is spread through saliva or mucus by coughing, sneezing or talking. Sharing utensils or cups can also spread the infection, the CDC said.
It can also spread when an infected person touches items or surfaces that are then touched by someone else.
CNN's Debra Goldschmidt contributed to this report.
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