16. Positive anti-hepatitis C (HCV) antibodies and a positive serum HCV RNA PCR. All positive HCV antibody results must be assessed by an electroimmunoassay enzyme-linked immunosorbent assay (EIA) assay and confirmed by a quantitative serum HCV RNA assay. Participants with positive HCV antibodies but undetectable serum HCV RNA may be considered for eligibility. Participants with negative anti-HCV antibodies but unexplained liver enzyme abnormalities must undergo a quantitative serum RNA assay to rule out false negative HCV serologies.