Impact of hcv infection on the liver

Since hepatic transaminases do not reliably predict the extent of hepatic injury, liver biopsy has been used to determine the inflammatory activity and the degree of fibrosis and, hence, disease prognosis. Key histologic features of chronic HCV infection include 1) patchy enlargement of the portal tracts with a predominant lymphocytic infiltrate, lymphoid aggregates, and piecemeal necrosis into adjacent lobules; 2) variable bile duct damage and loss; 3) varying degrees of microvesicular and macrovesicular steatosis; and 4) sinusoidal cell hyperplasia. Less commonly observed findings include lobular necrosis, hepatic cell dysplasia, multinucleation, and accumulation of Mallory-like bodies in hepatocytes. Definitive tissue diagnosis is based on the identification of viral RNA from tissue homogenates by polymerase chain reaction, although this is rarely used in clinical practice.

Several disease activity and fibrosis scoring systems (eg, Ishak, Knodell, Scheuer, Metavir and Batts, Ludwig) are used by pathologists, although no schema is universally considered most reliable. The extent of fibrosis and inflammation observed on liver biopsy can predict the progression of HCV to cirrhosis and can aid in the decision to treat (see Hepatitis C Feature Series 2, Issue 5). The risk of cirrhosis increases over time when the liver biopsy demonstrates significant periportal inflammation, bridging fibrosis, or both. By univariate analysis, several factors influence the progression of fibrosis. These factors include alcohol consumption of more than 50 g/d, male sex, age at infection, a serum ferritin level of 290 ng/mL or higher, and hepatic steatosis. Multiple regression analysis indicates that steatosis and periportal activity correlate with severe fibrosis.

Approximately 25-40% of patients with anti-HCV antibodies have transaminase levels within the reference range. In many of these patients, the HCV status is discovered incidentally during blood donation. Some patients have undetectable HCV RNA levels and therefore appear to have immunologically cleared their infection spontaneously, while others have active inflammation and possibly even cirrhosis. The reason for the latter observation is not clear, but it may be related to an association with HLA antigen DR13. Patients with reference range transaminase levels have a lower incidence of advanced inflammation and fibrosis relative to those with elevated transaminase levels. In patients with reference range transaminase levels and minimal pathologic changes on biopsy, one option is to monitor the disease without providing specific treatment.

Prevention of hcv infection

To date, screening the general population for HCV infection has been controversial. The 2004 US Preventive Services Task Force does not recommend screening for HCV infection in asymptomatic adults. Although further studies are needed, screening populations at high risk, such as injection drug users and pregnant females, especially if they are infected with HIV, may be reasonable.

Currently, no licensed vaccine to prevent HCV infection exists. However, counseling individuals infected with HCV may help prevent spread of the disease. Patients who do not have serologic evidence of immunity to hepatitis A and B should be vaccinated, especially since infection with the hepatitis A virus in patients with chronic HCV may result in a more severe infection than in patients without HCV.