Seven additional cases are considered "probable" and 20 more were deemed "suspect" at two high schools, two middle schools and elsewhere in the surrounding area, health officials said. The first case at the school was confirmed on March 2.
There's also another case of mumps in the village of Barrington and two new cases in Lake Zurich and Libertyville.
On Tuesday, the Toronto District School Board confirmed that two of its students were infected with the mumps virus, bringing the total of confirmed cases among students to three.
Yesterday, the tally of mumps cases in the city sat at 26 with only one deriving from a TDSB school.
Parents have been notified of the possible case of mumps.
"CPS is supporting the Chicago Department of Public Health as it investigates a potential case of mumps". School officials encourage anyone showing symptoms to stay home.
A suspected case means a positive blood test result has come back for mumps even though the person tested may not be showing signs of clinical symptoms, he said.
"However, if there are multiple cases in a school...we actually have the ability to exclude students who are not up-to-date with their immunizations from school", Dubey said.
District 220 officials initially notified parents, students and staff of the first confirmed case of mumps in a districtwide message February 28, describing how a student contracted the viral disease. Mumps is spread through coughing, sneezing and other contact with saliva.
Health officials say to look out for a low-grade fever, stiff neck and swollen salivary glands as symptoms of the virus.