This comes on the day the Lake County Health Department declared a mumps outbreak after Barrington High School reported three cases.
At Station and Prairie Middle Schools in Barrington, health officials have identified one probable case and eight suspected cases, she said.
One case of mumps is suspected at school on the North Side of Chicago.
"With spring break approaching, and other warm-weather social events coming up, students should be particularly cautious, especially if they are planning to travel", said Lake County Health Department executive director Mark Pfister.
Symptoms include fever, headaches, muscle aches, fatigue, and swollen and tender salivary glands under the ears. After being exposed to the virus it can take two to three weeks for symptoms to arise and a person can be contagious a couple days before those symptoms develop.
The possible case, which hasn't been confirmed, is at Helen C. Pierce School of International Studies, 1423 W. Bryn Mawr Ave., in the Andersonville neighborhood, the report stated.
In a newsletter, school officials assured parents that they shouldn't feel overly concerned about the case.
In rare cases the mumps can cause sterility, meningitis or even inflammation of the brain.
Parents that FOX 32 spoke to say school officials are staying on top of the new information, putting some parents at ease.
Good hygiene is also key, health officials say, and maintenance staff at the school has been instructed to focus on "high touch" surfaces in the building.