Chronic hepatitis B virus infection acquired in childhood: special emphasis on prognostic and therapeutic implication of delayed HBeAg seroconversion.

In high endemic areas of hepatitis B virus (HBV) infection, the vast majority of infection is acquired perinatally or during early childhood. The age of the patient is, therefore, almost equivalent to the duration of HBV infection. The natural history of chronic HBV infection consists of three chronological phases: immune tolerance, immune clearance and low replicative phases. The prevalence of hepatitis B e antigen (HBeAg) in asymptomatic HBV carriers is around 90% before 15 years of age, and decreases remarkably to less than 10% after 40 years of age. The immune clearance phase is characterized by a series of hepatitis flares and remissions. These will be followed eventually by HBeAg seroconversion, which is usually accompanied by remission of liver disease and confers favourable outcome. However, patients with persistent HBeAg seropositivity over 40 years of age are associated with a significantly higher risk for progression to cirrhosis than those with HBeAg seroconversion before 40 years of age, and thus should be considered as patients with 'delayed' HBeAg seroconversion. Antiviral or immunomodulatory therapy should be considered seriously for these patients.