Health officials have declared a mumps outbreak at a suburban Chicago high school after confirming a third case among its students.
The Lake County Health Department says it has nearly 20 suspected mumps cases at Barrington High School, along with an adult from Lake Zurich and a Libertyville High School student.
Those cases come as the U.S. is in the midst of one of the largest mumps surges in decades, with schools and college campuses in many states contending with outbreaks.
Barrington school district Superintendent Brian Harris said fewer than 10 of the school's some 3,000 students don't have confirmed mumps immunizations. He says 95 percent of the school's students attended class Tuesday.
