[Epidemiology and natural history of hepatitis B]

Area of Science:

• Hepatology
• Virology
• Immunology

Context:

• Hepatitis B virus (HBV) transmission occurs via parenteral, sexual, and perinatal routes.
• While acute hepatitis B can be fulminant in 1% of cases, the major challenge is chronic HBV infection, defined by HBs antigen carriage exceeding six months.
• Chronicity is common in children (up to 90%) and immunocompromised patients (30-100%), contrasting with immunocompetent adults (0.5-3%).

Purpose:

• To outline the transmission, chronicity, pathogenesis, and clinical outcomes of Hepatitis B virus infection.
• To highlight the public health significance of chronic HBV infection and its associated complications.
• To emphasize the need for universal vaccination strategies against HBV.

Summary:

• Chronic HBV infection involves complex host-virus interactions, viral factors like integration and mutation, and immune responses, leading to diverse clinical presentations.
• The evolution of chronic HBV infection is marked by viral replication fluctuations, spontaneous reactivations, and potential exacerbations.
• Chronic active hepatitis can progress to cirrhosis (1.3-5.9% yearly incidence), liver failure, or hepatocellular carcinoma, accounting for 80% of HBV-related morbidity and mortality.

Impact:

• Chronic HBV infection poses a significant public health burden, particularly in developing countries.
• Factors like immunosuppression, delta virus superinfection, and alcohol consumption significantly alter the disease's natural history.
• The 5-year survival for HBV-related cirrhosis varies between 52-82%, underscoring the severity of long-term complications and the importance of preventive measures like vaccination.