[Natural history of chronic hepatitis B]

An estimated 350 million people worldwide are chronically infected with hepatitis B virus (HBV). Three phases of chronic hepatitis B virus infection is are recognized: the immune tolerant phase (HBeAg-positive, high levels of serum HBV-DNA, normal ALT, and no evidence of active liver diseases), the immune clearance phase or chronic hepatitis phase (HBeAg-positive, high levels of serum HBV-DNA, elevated ALT, and active liver disease ), and the inactive carrier state or asymptomatic phase (HBsAg-positive in serum without HBeAg, HBV-DNA levels than < 10(5) copies/mL, and normal ALT levels). Chronic hepatitis B is classified into 2 major forms: HBeAg-positive disease (wild-type HBV) and HBeAg negative disease (pre-core/core promoter HBV variant). Both forms can lead to liver cirrhosis, hepatic decompensation and liver cancer. The purpose of this article is to review the principal aspects of natural history of chronic hepatitis B.