85: Hepatitis B and Hepatitis C Infection

Hepatitis B Infection

Key Points

• Disease summary:

  • Hepatitis B infection is caused by the hepatitis B virus (HBV), which is transmitted through percutaneous and sexual routes. With an estimated 400 million people with chronic hepatitis B worldwide, HBV infection is currently one of the most prevalent infections. In the United States, there are an estimated 1.25 million people with chronic hepatitis B. A hepatitis B infection acquired in adulthood results in development of protective antibodies approximately 95% of the time. In the remaining approximately 5%, a chronic hepatitis B infection is established, which can lead to end-stage liver disease in 2% to 10% per year and in some infection progresses to liver failure and hepatocellular carcinoma. In HBV acquired in infancy or childhood, the majority of people become chronically infected. Several drugs are available for treatment of chronic hepatitis B, but in the majority of patients, treatment is long term (lifelong in some) since HBV is difficult to eradicate.

• Major clinical forms of infection include

  • Chronic hepatitis B—Chronic hepatitis B is defined as persistence of the hepatitis B surface antigen (HBsAg) for more than 6 months. It can be divided into active and inactive disease based on detection of HBV DNA and degree of necroinflammatory disease in the liver. It can be subdivided into HBeAg positive (usually active disease) and HBeAg negative (can be active or inactive) chronic hepatitis B.

  • Resolved hepatitis B—Previous HBV infection without further virologic, biochemical, or histologic evidence of active virus infection or disease. Serologically this is distinguished by absence of HBsAg but presence of antibodies to the hepatitis B core antigen (anti-HBc) and surface antigen (anti-HBs)

• Differential diagnosis:

  • Autoimmune hepatitis, viral hepatitis A, C, and E, HDV coinfection or superinfection, alcoholic hepatitis, nonalcoholic steatohepatitis (fatty liver), sclerosing cholangitis, Wilson disease, alpha-1-antitrypsin-deficiency-related liver disease, drug-induced liver disease

• Monogenic forms:

  • Not available

• Family history:

  • Not available

• Twin studies:

  • One study showed that monozygotic twins, who were infected with HBV, were more likely to become chronically infected compared to dizygotic twins or siblings.

• Environmental factors:

  • Hepatitis B is an infectious virus so exposure to virus via percutaneous or sexual contact is necessary to acquire the infection.

• Genome-wide associations:

  • Strong association established between genetic variation around HLA-DPA1 and HLA-DPB1 genomic region and chronic outcome of acute infection in Asian populations.

• Single-nucleotide polymorphism (SNP) in KIF1B on chromosome 1p36.22 is associated with hepatocellular carcinoma (HCC) development in Asian chronic HBV carriers.

• Pharmacogenomics:

  • Not available

Diagnostic Criteria and Clinical Characteristics

Diagnostic Criteria for Hepatitis B

Diagnostic Evaluation

• Initial testing: HBsAg. Two positive tests separated by 6 months are required for the diagnosis of chronic hepatitis B.

• If chronic hepatitis B is diagnosed, then additional testing includes HBV DNA, hepatitis B e antigen, hepatitis B e antibody, liver function tests, liver imaging, and in some cases, a liver biopsy.