The Southern Nevada Health District has identified two patient sources that led to the hepatitis C outbreak at a local medical clinic. Health district officials say one patient had a procedure at the Endoscopy Center of Southern Nevada on July 25th, 2007. A second procedure took place on September 21st. Officials say the September patient was a known carrier of hepatitis C, and that the clinic knew that before the procedure. Investigators believe the dates in question are when clinic nurses allegedly contaminated single-dose medicine vials with reused syringes. A total of nine hepatitis C cases have been linked to the Endoscopy Center of Southern Nevada and its affiliated clinics. The first cases were reported in late February, when evidence of unsafe medical procedures at the clinic first surfaced. About 50,000 patients were urged to get tested for hepatitis and HIV as a precaution.