The Department of Health said the spread of such diseases can accelerate when people gather in large groups, such as at picnics, camps, fairs and other common warm-weather activities.
Health agencies have confirmed 328 mumps cases in central Ohio, and 196 of those are linked to Ohio State University. Officials said the origin of the outbreak might never be known.
A measles outbreak is being tracked a bit further to the northeast in a six-county area. Twenty-nine of the 42 confirmed cases are in Knox County. Officials said that outbreak began with unvaccinated travelers who visited the Philippines, which has had a measles epidemic.