Curriculum · Gastroenterology
Chronic hepatitis C
What it is
Chronic hepatitis C is infection with HCV, the hepatitis C virus. HCV is the most prevalent bloodborne infection in the West, the most common chronic bloodborne pathogen in the United States, and a leading cause of complications of chronic liver disease. It manifests as chronic liver disease because the acute infection is asymptomatic. Chronic HCV infection can cause cirrhosis and is a risk factor for HCC.
Causes and risk
The prevalence of the anti-HCV antibody in the United States is approximately 1.6% in non-institutionalized persons, and according to data from 1999 to 2008 approximately 75% of patients there living with HCV infection were born between 1945 and 1965. Other high-risk groups include injection drug users, recipients of blood transfusions before 1992, and those with HIV or an STI.
How it is diagnosed
The U.S. Preventive Services Task Force recommends screening for HCV infection in persons at risk for infection, and also one-time screenings for adults born between 1945 and 1965, a Grade B recommendation. Test for HCV in patients with chronic liver disease, as well as in patients with vasculitis, cryoglobulinemia, GN, and porphyria cutanea tarda. The order of the two tests is the point. Measurement of the anti-HCV antibody is the initial diagnostic study, and if it is positive the next test is HCV RNA, which determines whether there is active infection. A patient with spontaneous resolution of acute HCV, or who was treated successfully, shows clearance of the RNA but usually remains positive for the antibody, so the antibody by itself cannot say whether the infection is present now. Genotyping is performed at diagnosis to help choose the regimen. Normal aminotransferase levels, which occur in up to 40% of patients with chronic HCV, cannot exclude the diagnosis either. A worked case puts the same order: a man of 21, an active IV drug user who shares needles, with a normal ALT, a normal US abdomen and no cirrhosis, a positive anti HCV antibody, a negative HIV and a positive anti hep B surface antibody at a titer of 200; the next test to confirm active hepatitis C infection is the HCV viral load.