(CNN) -- Health authorities indicated Friday there have been 361 cases of mumps in central Ohio, a significantly higher number than was reported just a few weeks ago.
Most of these cases -- 208, to be specific -- have been linked to Ohio State University in Columbus, the city's health department said.
The 361 total includes cases from Franklin, Delaware and Madison counties and was current as of 2:30 p.m. Friday. Some 139 of those diagnosed were students at Ohio State, while a number of others worked at or otherwise had a connection to the university.
As recently as March 21, the same agency was reporting 63 mumps cases, of which 45 were tied to the university. The outbreak originated in February with a cluster of cases at Ohio State.
Melanie Amato, an Ohio Department of Health spokeswoman, attributes the spike to many students heading home, where they could end up spreading mumps or at least be seen and diagnosed by doctors.
"We don't expect the numbers to go down soon," Amato said.
Eleven people have been treated at area hospitals for mumps, according to Columbus Public Health. But none were still in hospitals as of Friday, and no deaths have been linked to the disease, Amato said.
Those affected range in age between 4 months and 80 years old, with about 60% being female.
The Ohio Department of Health reports the first symptoms tied to this outbreak arose on January 7. Jose Rodriguez, a Columbus health department spokesman, has said that the earliest OSU case was on February 11.
There is a vaccine available for mumps, but it's only 88% effective, Amato points out.
She explains: "A lot of these people who got mumps were vaccinated."
Mumps typically begins with a fever, headache, muscle aches, fatigue and loss of appetite, which is followed by the swelling of salivary glands, according to the CDC. It is "a highly infectious disease" that spreads the same way as a cold or flu does -- through respiratory droplets when someone coughs or sneezes.
There is no specific treatment for mumps, and patients usually recover after a week or two, but occasionally the disease can cause serious complications such as encephalitis, meningitis, deafness or inflammation of the breasts or ovaries in girls who have reached puberty, the CDC said.
Five days of isolation is required, "and that can be complicated in a university setting," according to Rodriguez. Even more frightening -- one-third of cases have no symptoms, he said.
Mumps isn't the only infectious disease outbreak that Ohio is dealing with. Earlier this week, authorities reported 68 people had come down with measles in the state, part of what is already an 18-year high of measles cases in the United States.