ウイルス性肝炎：A型からE型まで

抄録

Viral hepatitis is the most common cause of acute and chronic hepatitis. The term viral hepatitis generally refers to infections resulting from one of the hepatotrophic viruses: hepatitis A, B, C, D, or E. These viruses can be broadly divided into those transmitted via the fecal-oral route (hepatitis A and hepatitis E), and those by blood, blood products and body fluids (hepatitis B, C and D). Hepatitis A, B and C represent the major public health problems. In the case of HAV, older age groups (over 50) are now deemed at risk. Hepatitis E is rarely reported in Japan, and most Japanese patients have been recognized as an imported infection. Recently, however, the presence of indigenous HEV (genotypes III and IV) and its animal reservoirs have been disclosed in our country. The epidemiology of hepatitis B is changing in response to vaccination particularly in preventing vertical (maternal) transmission. Hepatitis C is another important cause of death worldwide. The infection easily becomes refractory and the chronicity contributes to the development of cirrhosis and hepatocellular carcinoma. Development of sensitive and specific immunoassays, as well as polymerase chain reaction for recognition of viral genes, has enabled detection of specific agents. This has allowed for identification of infected patients and monitoring response to therapy. Additionally, serologic markers have allowed for isolation of contaminated blood products and a reduction in the spread of disease. No approved test is available to diagnose hepatitis E. This article briefly explores the outline of the risk factors, epidemiology, clinical and laboratory characteristics, and treatment of the hepatotrophic viral infections.