Hepatitis B virus (HBV) infection
Hepatitis B virus is a bloodborne and sexually transmitted DNA virus that causes acute hepatitis and, when infection becomes chronic, progresses through immune-tolerant, immune-active, immune-control, and reactivation phases toward cirrhosis and hepatocellular carcinoma. Diagnosis rests on hepatitis B serology, chronic infection is treated with entecavir or tenofovir, and reactivation during immunosuppression is prevented with prophylactic antiviral therapy.
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What this article covers
- Overview
A bloodborne DNA virus spanning self-limited acute hepatitis to lifelong chronic infection: hepatitis B virus (HBV) infects an estimated 240 million people worldwide and can cause acute hepatitis…
- Epidemiology
Approximately 240 million people are infected with HBV worldwide, one of the most common chronic viral infections globally.
- Risk factors
Perinatal exposure to an HBsAg-positive mother: the highest-risk route, conferring a 90% risk of chronic infection in the newborn if untreated.
- Pathophysiology
Immune-mediated, not directly cytopathic, liver injury: liver injury in acute and chronic hepatitis B results from the host cytotoxic T-cell response against infected hepatocytes rather than viral replication alone.
- Clinical features
Most acute infections in adults are asymptomatic or mild: only about 30% of adults develop clinically apparent jaundice from acute HBV infection.
- Differential diagnosis
Hepatitis A, D, and E virus infection: hepatitis A/E have a fecal-oral exposure history and negative HBsAg; hepatitis D requires concurrent or superimposed HBV infection (positive HDV IgG in an HBsAg-positive patient).
- Diagnosis
HBV infection is diagnosed and staged by hepatitis B serology, not a scoring system: hepatitis B surface antigen (HBsAg) positivity confirms current infection; a positive IgM anti-HBc with HBsAg…
- Management
First, determine whether infection is acute or chronic and whether treatment criteria are met.
- Complications
Cirrhosis and hepatocellular carcinoma: about 40% of deaths in HBV-infected persons older than 40 years relate to hepatocellular carcinoma or decompensated cirrhosis; risk is highest with HBV DNA…
- Prognosis
Acute infection in a healthy adult usually resolves spontaneously, with chronic progression risk inversely related to age at infection (90% newborns versus about 5% adults).
- Prevention
Universal hepatitis B vaccination is the foundation of prevention: standard 3-dose series (0, 1, 6 months) with Engerix-B or Recombivax HB, an accelerated 4-dose series (0, 1, 2, and 12 months) for…
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Hepatitis A virus is a fecal-oral RNA virus that causes acute, host-immune-mediated hepatitis with a prodrome followed by jaundice, aminotransferases often exceeding 1,000 U/L, and full recovery in at least 90% of patients within 3 to 6 months. Diagnosis rests on HAV IgM, treatment is supportive, and prevention centers on a 2-dose inactivated vaccine plus prompt postexposure prophylaxis.
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