Hepatitis E virus (HEV) is an emerging pathogen belonging to a newly recognized family of RNA viruses (Hepeviridae). HEV is an important enterically transmitted human pathogen with a worldwide distribution. It can cause sporadic cases as well as large epidemics of acute hepatitis. Epidemics are primarily waterborne in areas where water supplies are contaminated with HEV of human origin. There is increasing evidence, however, that many animal species are infected with an antigenically similar virus. A recently isolated swine virus is the best candidate for causing a zoonotic form of hepatitis E. The virus is serologically cross-reactive with human HEV and genetically very similar, and the human and swine strains seem to be cross-infective. Very recent evidence has also shown that swine HEV, and possibly a deer strain of HEV, can be transmitted to humans by consumption of contaminated meat. In this review, we discuss the prevalence, pathogenicity, diagnosis and control of human HEV, swine HEV, the related avian HEV and HEV in other hosts and potential reservoirs.
