there are now 120 confirmed hiv cases and 10 preliminary positive cases tied to scott county , about 30 miles north of louisville , kentucky .
outbreak has occurred among intravenous drug users and primarily involves the use of the high-powered prescription painkiller opana .
health officials who declared an epidemic last month have said they expect the number of cases to rise as more people are tested .
gov. mike pence approved a short-term needle exchange program two weeks ago to help combat the problem .