[Hepatitis B and C: natural course of disease]

Significant progress in the understanding of the natural history of hepatitis B and C has been made in recent years due to molecular diagnosis techniques. The most important biologic feature of hepatitis B and C viruses (HBV, HCV) is their ability to cause chronic hepatitis. The natural course of HBV infection is variable, ranging from inactive HBsAg carrier state to progressive chronic hepatitis that can evolve into liver cirrhosis and hepatocellular carcinoma. HBeAg-negative chronic hepatitis is due to a naturally occurring HBV variant with mutations in the precore or basic core promoter regions. It accounts for the majority of cases in many European countries and is generally associated with a more severe liver disease. The morbidity and mortality in chronic hepatitis B are linked to the evolution to cirrhosis and hepatocellular carcinoma. The progression of fibrosis is strongly associated with persistent active viral replication When the diagnosis is made, the 5-year cumulative incidence of developing cirrhosis ranges from 8% to 20%. The 5-year cumulative incidence of hepatic decompensation is 20%. Hepatocellular carcinoma is one of the most common cancers worldwide, 75% of which are related to chronic HBV infection. Coinfection with hepatitis D virus can lead to a more progressive liver disease in a shorter period of time. Hepatitis C virus infection becomes chronic in 80% of infected persons resulting in different stages of chronic hepatitis, with 20%-30% progressing to cirrhosis within 20 years period. The progression of fibrosis determines the ultimate prognosis. The major factors known to be associated with fibrosis progression are older age, male gender and alcohol consumption. Viral load and genotype do not play a role in the disease progression. Progression to fibrosis is more rapid in immunocompromised patients.