Three new cases of mumps were confirmed at Station Middle School in Barrington with several others that could test positive.
There are six confirmed cases at Barrington High School with more than a dozen other probable cases.
The district said schools are operating as normal and there has not been a major drop in attendance.
On Tuesday, the health department released an official count of mumps cases in Lake County:
Barrington High School: 6 confirmed, 16 probable, 2 suspect
Station Middle School (Barrington): 3 confirmed, 4 probable, 2 suspect
Prairie Campus School (Barrington): 5 suspect
Roslyn Road School (Barrington): 1 suspect
Fremont Intermediate School (Mundelein) 1 suspect
Libertyville High School: 1 suspect
Carmel High School: 1 suspect
Daniel Wright Junior High School (Lincolnshire): 1 confirmed case
Other Lake County cases:
1 confirmed (Barrington)
3 suspect cases
For more information, visit: https://www.lakecountyil.gov/3875/Mumps
Mumps outbreak grows in northwest suburbs