The taxonomy and properties of type E hepatitis virus (HEV) classified to genus Hepevirus, family Hepeviridae, have been described. Genotypes I, II, III and IV have been distinguished. The disease occurs in humans mainly in developing countries. However, during recent years it has been diagnosed in industrialized countries, such as Japan, USA and European countries, as well, even without earlier contact of people with a population living in the Third World areas. Contacts of people with pigs, resulting in type E hepatitis or specific seroconvertion indicate that these animals are the reservoir of HEV. Particularly genotypes III and IV, which occur in swine, participate in such cases in the etiology of type E hepatitis in humans. This finding indicates that type E hepatitis in humans is, at least in several circumstances, a zoonotic disease. Beside swine, which are the main source of the virus, other species, such as ruminants, rodents, and poultry, are also carriers of the mentioned genotypes III and IV. The infection takes place by the oroenteral route, which is the only way of spreading the infection and disease. The virus excreted with the feces contaminates the environment. Independently from other pathogens, hepatitis in swine can be caused by the mentioned virus; however, the severity of pathological symptoms can be increased by coinfection with other viruses, particularly the porcine circovirus 2 (PCV2).
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