Features of hepatitis E virus infection in Japan

Hepatitis E virus (HEV) is a major cause of acute hepatitis in many developing countries. HEV is transmitted principally by the fecal-oral route, and water-borne epidemics are characteristic of hepatitis E. Recently, there is growing consensus that HEV-associated hepatitis also occurs among individuals in industrialized nations who had no history of travel to endemic areas. Zoonotic spread of HEV has been suggested as human and swine HEV strains are closely related genetically and experimental cross-species infection of swine HEV to a chimpanzee and that of human HEV to swine have been demonstrated. This review describes the clinical, epidemiological and virological characteristics of domestic HEV infection in Japan, the genetic relatedness of Japanese human and swine HEV strains, and possible modes of HEV transmission, emphasizing that HEV should be considered in the diagnosis of acute or fulminant hepatitis of non-A, non-B, non-C etiology, even in patients who have not traveled abroad.