The Ohio Department of Health announced last week mumps cases reported in Delaware County are now officially considered part of an outbreak that started in Franklin County.
The department made the announcement Wednesday, the same day the Delaware General Health District reported the number of probable mumps cases in the county had grown from seven to 10.
Mumps is a viral disease spread through infected saliva, with symptoms including swelling of the salivary glands, fever and headaches.
Officials think the current outbreak might have started at Ohio State University in February.
Columbus Public Health reported Wednesday that 119 cases of the mumps -- including 24 involving people with no apparent ties to Ohio State -- have been reported in Franklin County.
Whereas cases from Delaware County and other central Ohio counties will now be considered part of the same outbreak, officials still aren't positive how the infection spread to Delaware County.
"We haven't been able to establish a strong link to (OSU) or any of those (Franklin County) cases," said Traci Whittaker, spokeswoman for the Delaware General Health District.
Although there is no direct link to Franklin County's cases yet, Whittaker said a majority of the people with probable cases of the mumps in Delaware County live in the southern part of the county.
Three of the probable cases involve students in Olentangy schools -- one each from Olentangy High School in Lewis Center, Olentangy Liberty High School in Liberty Township and Scioto Ridge Elementary School in Liberty Township.
Those students, who reported the symptoms almost two weeks ago, were required by the Ohio Administrative Code to miss five days of classes.
District officials said school nurses also contacted the families of students who had not been vaccinated or have weakened immune systems.
Officials recommend anyone who has not received two mumps vaccinations or does not remember if they received both make an appointment to be vaccinated.
Most people born after 1957 received two doses of the MMR vaccine, which is largely effective in preventing the disease.
People born before 1957 most likely had the disease at one time and now are considered immune.
The Delaware General Health District recommends residents wash their hands frequently, avoid sharing utensils and cover their coughs and sneezes to avoid spreading the mumps.
Whittaker said one of the best things you can do to prevent the spread of mumps if you're infected is to do little at all.
"The recommendation is, obviously, if you're sick, stay home," she said.