Six students at San Diego State University have been diagnosed with confirmed or probable mumps in the last week, the San Diego County Health and Human Services Agency (HHSA) confirmed Wednesday.

All six students live off campus at the BLVD63 apartment complex on El Cajon Boulevard near 63rd Street, according to the HHSA.

“These six mumps cases represent a small outbreak of this highly contagious viral disease,” said Wilma Wooten, M.D., M.P.H., County public health officer. “The best way to prevent mumps is by getting the measles, mumps and rubella, or MMR vaccine.”

The cases at BLVD63 come on the heels of an uptick in local cases in recent months. In addition to the cases at BLVD63, there have been four other cases in the county so far this year. In 2019, San Diego County recorded 66 mumps cases, compared to nine cases in 2018 and 15 the year before that. Last year’s increase marks a 25-year high in mumps cases in the county.

The HHSA will conduct free vaccinations at BLVD 63 from 3 to 6 p.m. on Feb. 27 and 28. Residents and SDSU students can get their vaccines on a first come, first served basis, the county said.

Paul Kohlroser, one of the six patients, told NBC 7 his friend is doing fine, all things considered.

“He's not in pain. He didn’t have a fever. It’s like his cheeks were very swollen," Kohlroser said.

Kohlroser and his friend are exchange students from Austria who arrived in January. Kohlroser's friend’s roommate started showing symptoms a few days before his friend did, he said.

Kohlroser is staying in touch with his recovering buddy by text, trying to keep him in good spirits while he and his roommate have been isolated in their room for at least the past five days.

“I told him he shouldn’t think of himself. Think of others so no one else will get it," Kohlroser said.

SDSU sent a letter to students Wednesday saying the sick students are "self isolating” at BLVD63 and won't attend classes or campus activities until they're well.

BLVD63 notified its residents of the health concerns associated with mumps.

Resident Justari Jones said he’s practicing some of the precautions listed.

“I’m aware of not sharing drinks with anyone and covering up when I cough," said Jones.

Two doses of the measles, mumps and rubella vaccine, or MMR vaccine, is required for students to be enrolled at SDSU, according to the university’s website.

When asked if the six patients were vaccinated, university officials responded:

"SDSU cannot disclose specific information about the individual students, their academic information or other personal details, which are private as determined by federal law"

Students can contact the SDSU Student Health Services at (619) 594-4325 or the Nurse Advice Line at (858) 225-3105, which is available after 4:30 p.m. Monday through Friday, on weekends and when the school is closed.

Within 48 hours, most people diagnosed with mumps experience the swelling of their salivary glands, leading to puffy cheeks and a tender, swollen jaw.

Mumps can be prevented with the MMR vaccine, which also protects against measles and rubella, according to the Center for Disease Control (CDC). Two doses of the vaccine are recommended -- one at 12 to 15 months of age and another at 4 to 6 years of age.

The CDC said the U.S. mumps vaccination program began in 1967 and, since then, there has been a 99 percent decrease in mumps cases in the United States with periodic outbreaks on colleges or other places where people are in close contact.