Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (187 page)

   HCV is an enveloped, single-stranded RNA Flavivirus. HCV infections occur worldwide but with geographic variation in prevalence of infection. Transmission is almost exclusively by percutaneous exposure. Transmission by sexual and perinatal exposure is rare.

   In 2011, a CDC study showed the rate of newly diagnosed HCV infection of 85 per 100,000 population. Among newly diagnosed patients, only 50% had testing for active infection (i.e., HCV RNA detection). The highest prevalence and percentage of deaths were seen in patients born during the period 1945–1965.

   In 2012, the CDC published revised recommendations for HCV testing, as described below. The new recommendations were issued (1) to reflect changes in diagnostic tests, like improved immunoassays and unavailability of RIBA HCV confirmatory testing; (2) to expand one-time screening of everyone born between 1945 and 1965, regardless of specific risk factors; (3) to include initial evaluation for active infection (HCV viremia detection) in all patients with positive HCV serology to facilitate optimal treatment. The recommendations stress the impact of new direct-acting antivirals for improved outcome in patients with chronic HCV infection and likely decreased transmission of infection.

   Specific risk factors are well described for HCV acquisition, but 38% of patients report no known risk for exposure. Significant risk factors for HCV infection include the following:

   Any person born from 1945 through 1965

   HIV infection

   History of IV drug abuse

   History of blood product transfusion or organ transplantation before July 1992 or clotting factor concentrate before 1987

   History of long-term hemodialysis

   Known exposure to HCV, like health care workers exposed to HCV-positive blood by needle-stick injury or the recipient of blood or organ transplant from a patient subsequently shown to be HCV positive

   Children born to HCV-positive mothers

   Persistently elevated serum ALT