INLAND EMPIRE Two cases of tuberculosis are being investigated in widely separated areas of Riverside County. A student at Desert Mirage High School in Thermal is hospitalized. Letters are being sent to parents of students who may have had contact with the youth urging them to get tested as a precaution. In the other case, an employee who works for the Riverside County Department of Public Social Services in Lake Elsinore is receiving treatment at home. Health officials believe the individual had minimal contact with the public while the person was infectious. “TB is a treatable illness once it is diagnosed. The risk of transmission is low in both instances but we are working to ensure that anyone who may have been exposed will be tested as a precaution,” said Dr. Cameron Kaiser, Riverside County public health officer.