Indiana University officials say the number of students diagnosed with mumps has more than doubled since last week to 16.
University spokesman Chuck Carney said Wednesday that nine of the cases are linked to a single fraternity he declined to identify.
Carney says university officials have been in contact with the Indiana State Department of Health and the Centers for Disease Control and Prevention.
The new total compares to seven cases announced last week .
The first two cases were confirmed in February and a campus outbreak of the illness was declared last month after a third case was confirmed.
Free vaccines are available for anyone who has had close contact with infected students.
Mumps is a viral illness that affects glands that produce saliva.