Hepatitis B Virus Infection
A viral liver infection that can become chronic, leading to progressive liver damage, cirrhosis, and a high risk of liver cancer.
Emergency Management: Variceal bleeding requiring emergent volume resuscitation, octreotide (50 mcg IV bolus then 50 mcg/hr), and upper endoscopy for banding.
Hepatitis B is a viral infection that attacks the liver, caused by the partially double-stranded DNA hepatitis B virus (HBV) of the Hepadnaviridae family. It can result in acute or chronic liver inflammation, with chronic infection defined as the persistence of hepatitis B surface antigen (HBsAg) for more than 6 months.
Detailed Overview
HBV is transmitted through contact with infectious blood or body fluids. While most adults clear the infection spontaneously, infants and young children are at a high risk (up to 90%) of developing chronic infection. Chronic HBV is characterized by phases of immune tolerance, immune clearance, inactive carrier state, and reactivation. The virus is not highly cytopathic; rather, the host's cytotoxic T-cell response against infected hepatocytes drives liver injury, fibrogenesis, and ultimately cirrhosis or hepatocellular carcinoma (HCC).
Epidemiology & Demographics
An estimated 296 million people worldwide live with chronic hepatitis B, with highest prevalence in WHO African and Western Pacific regions (>8%). Approximately 820,000 die annually from HBV-related liver diseases.
Etiological Mechanism
Infection with Hepatitis B virus (HBV).
Primary Causes
Hepatitis B virus (HBV)
HBV enters hepatocytes via the NTCP receptor. Its genome is converted into covalently closed circular DNA (cccDNA) in the nucleus, serving as a template for viral replication. Hepatocyte damage is mediated by the host CD8+ T-cell response attacking viral antigens (HBsAg, HBcAg) expressed on the cell surface, leading to apoptosis, necrosis, and subsequent liver fibrosis driven by hepatic stellate cell activation.
Diagnostic Criteria & Guidelines
Persistence of serum HBsAg for > 6 months. Acute infection is indicated by HBsAg + IgM anti-HBc.
Nucleos(t)ide analogues: Entecavir 0.5 mg PO daily OR Tenofovir disoproxil fumarate (TDF) 300 mg PO daily OR Tenofovir alafenamide (TAF) 25 mg PO daily.
Second-Line & Adjunctive Therapy
Pegylated interferon-alfa-2a 180 mcg SC weekly for 48 weeks (in highly selected non-cirrhotic patients).
Surgical & Procedural Management
Liver transplantation for decompensated cirrhosis or early-stage HCC (Milan criteria).
Patient Counseling & Advice
Emphasize life-long daily medication adherence. Advise on safe sex and testing for sexual partners and household contacts.
Follow-Up & Monitoring Schedule
ALT and HBV DNA every 3-6 months. HCC surveillance with abdominal ultrasound every 6 months for cirrhotic patients and high-risk groups.
Preventive Strategies
Recombinant HBV vaccine (e.g., 3 doses at 0, 1, 6 months). Hepatitis B immune globulin (HBIG) for post-exposure prophylaxis.
Five-year survival for compensated cirrhosis is >80%. Current therapies effectively suppress viral replication but rarely achieve functional cure (HBsAg loss).