Philadelphia's Temple University is urging its students and faculty to get mumps vaccinations amid an outbreak that has likely sickened more than 100 people over two months.

As of Tuesday, the city's Department of Public Health said there were 105 cases of mumps associated with Temple's outbreak. Of those cases, 18 have been confirmed and 87 were probable. Six of those cases were outside of Philadelphia, the department said.

The school first announced the outbreak at the end of February, just before spring break, with four confirmed cases of the disease.

"I think we have a handle on it, but we're expecting a third wave," Marky Denys, the university's student health director, told CBS Philly.

Mumps is a viral infection that spreads through infected saliva. An infected person can spread it simply by sneezing or coughing around other people, or by sharing utensils or cups with another person, according to the Mayo Clinic's website.

The university is offering free vaccines to its students and faculty at walk-in clinics this week.

"Because of the nature of mumps - it can take up to three weeks for someone who was exposed to become symptomatic - we realize that the outbreak will continue for a while longer, but hope that these clinics help bring it to a close," James Garrow, a spokesman with the Philadelphia Department of Public Health, said in a statement.

The MMR vaccine protects against measles, mumps and rubella. Though it does not guarantee protection, those who are vaccinated generally experience milder symptoms of the disease if it's contracted. A higher number of vaccinated people also helps limits the size, duration and spread of outbreaks, according to the U.S. Centers for Disease Control and Prevention.

"There is no treatment for mumps, and it can cause long-term health problems. Before there was a vaccine, mumps was the leading cause in the U.S. for viral encephalitis (infection of the brain) and sudden deafness," the CDC's website says.

In some cases, public health officials may recommend two or three doses of the vaccine depending on a person's risk of contracting the disease, according to both the CDC and the Mayo Clinic.

"A study of a recent mumps outbreak on a college campus showed that students who received the third dose of MMR vaccine had a much lower risk of contracting the disease," the Mayo Clinic's website says.