Clinical and epidemiological implications of swine hepatitis E virus infection

In nonendemic areas, most patients with acute hepatitis E were infected through traveling to endemic areas. However, some patients did not have a history of foreign travel before infection. Furthermore, high seroprevalence rates of antibody to hepatitis E virus (anti‐HEV) were found in the general adult population in some countries without any recorded outbreak of hepatitis E. The significance of anti‐HEV assay in these subjects remains obscure. To study if swine might be a source of HEV infection, HEV was tested in sera of 235 pigs in Taiwan, and from 5 patients with acute HEV infection who either denied or did not provide any foreign travel history. Three (1.3%) pigs had detectable swine HEV RNA. The swine and human HEV strains from Taiwan formed a monophyletic group, distinct from three previously reported groups: the United States human and swine HEV strains, the Mexico strain, and the largest group composed of the Asian and the African strains. The identity of nucleotide sequences was 84–95% between swine and human HEV strains in Taiwan, and 72–79% between Taiwan strains and those from different areas. The predicted amino acid sequence of a Taiwan swine HEV strain within the peptide 3‐2 used in commercial anti‐HEV assay showed a high identity (91–94%) with those of other human and swine HEV strains. Swine may be a reservoir of HEV and subclinical swine HEV infection may occur. Cross‐reactivity of current anti‐HEV assay may account for the high prevalence rate of anti‐HEV in the general population in nonendemic areas. J. Med. Virol. 60:166–171, 2000. © 2000 Wiley‐Liss, Inc.