Three male patients with sporadic acute hepatitis E in Sendai, Japan, who were domestically infected with hepatitis E virus of genotype III or IV.

Recent studies indicate that hepatitis E virus (HEV) infection occurs not only in developing countries but also in industrialized nations. However, the characteristics of domestic infections of hepatitis E in Japan are not fully understood. We analyzed serum samples from 34 patients who were seen at a city hospital in Sendai, Japan, between January 1997 and December 2002, and who had been given the diagnosis of sporadic acute hepatitis of non-A, non-B, non-C etiology. Among these 34 patients, 3 (9%; all men; aged 54, 59, and 61 years) were positive for both IgG and IgM anti-HEV antibodies and for HEV RNA. The HEV isolates (HE-JAS1 and HE-JAS3) obtained from case 1 and case 3, respectively, segregated into genotype III; they had the highest nucleotide sequence identity, of 99.5% and 99.0%, with HE-JA7 and HE-JA8, respectively, both of which had been isolated in Iwate, a neighboring prefecture of Sendai. In contrast, the remaining HEV isolate (HE-JAS2), obtained from case 2, segregated into genotype IV; it had the highest nucleotide sequence identity, of 99.8% and 99.3%, with JKK-Sap and HE-JA3, respectively, both of which had been isolated in Hokkaido, Japan, although case 2 had never been to Hokkaido. Our three patients with hepatitis E had not traveled abroad in the preceding 1 year, had had no contact with pigs, and no history of blood transfusion. These results indicate that HEV should be considered as an etiological agent of acute hepatitis of non-A, non-B, non-C etiology in Japan. The risk factor(s) for acquiring domestic HEV infection in Japan needs to be clarified in future studies.