Occult hepatitis C virus infection revisited with ultrasensitive real-time PCR assay.

Occult hepatitis C infection is regarded as a new entity that should be considered when diagnosing patients with a liver disease of unknown origin. Using an ultrasensitive real-time PCR assay, we demonstrated that occult hepatitis C virus (HCV) infection cannot be found in peripheral blood mononuclear cells of patients with cryptogenic liver diseases, HCV--associated systemic vasculitis, or connective tissue diseases. The significance of such occult infection must be elucidated.