Columbus Public Health officials are investigating a mumps outbreak that started at Ohio State University that is believed to have started in mid-February.
Late last week it had sickened 40 people and that number could rise.
Between Feb. 11 and March 21, there were 40 cases reported -- 32 affecting OSU students, four staff members, 1 family member and three people with strong links to the university.
Health officials say of those cases, 18 were female and 22 were male, all between the ages of 18 and 48.
For a city that typically sees one mumps case a year, health officials are taking action, said Jose Rodriguez, spokesman for the health agency.
"Most people today are vaccinated and it is between 80- and 90-percent effective," he said.
"So, hopefully, most people are protected against the mumps. These outbreaks don't happen that often but they do happen."
CPH has issued warnings throughout the state and country, so it can investigate and follow up with each case to track its origins, Rodriguez said.
"We are starting to see an increase in the number of cases outside of the university setting," he said. "And it's exactly what you'd expect.
"Students live in a university family, so when you have outbreaks like this it affects the larger community."
Mumps is a viral infection passed through respiratory droplets. Its symptoms mimic those of influenza -- body aches, chills, fever and headaches, plus swelling of the salivary glands.
Those infected are typically sick between 12 and 25 days. People are most infectious two days prior and five days after symptoms surface.
In one-third of cases, people do not develop symptoms, meaning they can pass along the virus without knowing it.
Those who do exhibit symptoms are asked to cover their coughs and sneezes and isolate themselves so they don't infect others, Rodriguez said.
Most children get mumps vaccinations when they're infants and get booster shots years later.
There is no cure for mumps, although physicians can treat the symptoms.
Otherwise, those who are unsure if they were inoculated are encouraged to get the MMR vaccine, which covers measles, mumps and rubella.
In 2006, the Midwest experienced a multi-state outbreak involving 6,584 people. A current outbreak at Fordham University in New York City has resulted in 13 cases reported on two campuses.
"Any time you have an outbreak in which it's a highly infectious disease it's a concern," Rodriguez said.