The natural history of chronic hepatitis B infection

Chronic hepatitis B infection is a global health problem that affects about 300 million people. Of these, 75% are Chinese. Most Chinese who become chronic carriers, contract the virus during the perinatal period. The natural history of these chronic hepatitis B carriers includes an initial immune tolerance phase, followed by immune clearance and an inactive hepatitis B non-replicative phase with the development of cirrhosis that may be complicated by hepatocellular carcinoma. The classification of hepatocellular carcinoma has recently been revised. Based on immunohistochemical studies, it has been found that patients with hepatocellular carcinoma and biliary markers have a poorer survival than patients with hepatocellular carcinoma but who have negative biliary markers. Sometimes, a fourth phase, a hepatitis B envelope-negative hepatitis B virus replicative phase, reflecting the emergence of a pre-core mutant strain, may follow. Our improved understanding of the natural history of chronic hepatitis B infection has led to more effective approaches towards the control of this viral infection and its sequelae. Most importantly, immunisation against hepatitis B virus in the perinatal setting has been shown to prevent chronic infection.