Natural history of chronic hepatitis B virus infection

In the last years notable steps have been done towards the understanding of the biology of Hepatitis B Virus (HBV), its natural history and immunopathogenesis, while succesful universal vaccination programs were implemented around the world and important advances in antiviral therapeuthics occurred. Nevertheless, HBV infection remains a public health problem with nearly 350 million carriers worlwide. The natural history of chronic hepatitis B and the spectrum of its clinical forms are complex and variable.We review the natural history of chronic HBV infection describing the early replicative phase and late or non-replicative (inactive carrier) in those patients who adquired the infection during adulthood and the immune tolerant phase, immune clearance and non-replicative in those who acquired the infection in the perinatal period. Emphasis is made in the course of HBeAg negative chronic hepatitis and occult hepatitis B. The complexity of the natural history of hepatitis B depends on viral features, hepatocyte behavior and patient immune response. The intrinsic and extrinsic HBV factors associated with the progression to cirrhosis and hepatocellular carcinoma are also reviewed.KEYWORDS: Hepatitis B, Natural history, liver cirrhosis, hepatocellular carcinoma.