Viral hepatitis in East Asia.

Viral hepatitis has a high prevalence in East Asia and is an important problem. Identification of the individual hepatitis viruses. A-E, has enabled researches to investigate the epidemiology and pathogenesis of viral hepatitis and its sequelae, and possible means of prevention. Because of improvement in hygiene in East Asia in recent decades, hepatitis A virus infection has decreased markedly. However, this has resulted in the younger population being susceptible to hepatitis A. Fortunately, effective active immunization for hepatitis A has become available. Hepatitis B is still rampant, especially in the southern part of East Asia where chronic infection is common. Patients who are chronic hepatitis B virus carriers are reservoirs for the virus and have a much higher risk of chronic liver disease and hepatocellular carcinoma (HGC). Currently, hepatitis B infection is being brought under control in East Asia through mass immunization. Serologic and molecular epidemiologic studies have also revealed that Hepatitis C is prevalent in the region. Hepatitis C virus also contributes to the development of cirrhosis and HCC. No effect immunization is currently available, and hepatitis C can only be controlled by preventative measures. The epidemiology and pathogenesis of viral hepatitis is discussed in this review, including new viral hepatitis agents possibly responsible for non-A-E hepatitis.