Introduction

Hepatitis B virus infection is a global public health problem, with approximately 400 million people chronically infected.1 2 Each year it causes more than 500 000 deaths worldwide. Outcome of acute hepatitis B virus infection ranges from asymptomatic subclinical infection (70%) and symptomatic acute hepatitis (30%) to fulminant hepatic failure (0.1-0.5%).3 A proportion of people infected with hepatitis B virus (5%-10% among adults) progress to chronicity, defined as persistence of infection for more than six months.4 The rate of chronicity is much higher among neonates and children. The spectrum of chronic hepatitis B virus infection ranges from the asymptomatic carrier state to chronic hepatitis B, liver cirrhosis, and hepatocellular carcinoma. The clinical course of hepatitis B virus infection is complex and is influenced by several factors (box 1). Overall, chronic hepatitis progresses to end stage liver disease in 15-40% of patients.5 The pathophysiology of chronic hepatitis B virus infection has been reviewed elsewhere.6

The magnitude and clinical consequences of chronic hepatitis B make a strong case for its prevention and treatment. This review, based on a Medline search and the authors' knowledge arising from their interest in the subject, summarises current knowledge about these aspects of hepatitis B virus infection.

Prevention of hepatitis B virus infection

Several strategies have been shown to prevent hepatitis B virus infection (box 2). Vaccination is the mainstay of prevention. Specific hepatitis B immunoglobulin (HBIg) and lamivudine are useful in specific settings.