Public health officials in Illinois say that there have been 82 cases of mumps reported through the end of April.
That's more than triple what was reported in all of last year.
The Illinois Department of Public Health says this year's total is already the highest since 2008 when 91 cases were reported.
Officials say that they don’t know there are so many cases.
Nine cases alone were reported among students last week on the University of Illinois' Urbana campus.