Seroepidemiology of hepatitis E on Japanese expatriates in Southeast Asian countries: A study at a clinic in Singapore

A two-phase study was conducted in order to examine anti-hepatitis E virus (HEV) antibody prevalence among Japanese expatriates in Southeast Asian countries at a clinic in Singapore serving Japanese expatriates. In phase I of the study, we identified a 20 month series of adult patients with abnormal liver function tests on routine medical examination or diagnostic evaluation. Serum was collected from the 179 patients from January 1993 through August 1994 and was analyzed for IgG and IgM anti-HEV antibodies with HEV-ELISA kits from Genelabs Diagnostics (GD). Out of 179 (13.4%) patients, 24 were positive for IgG anti-HEV. An IgM anti-HEV ELISA kit (GD) was available for the last 142 patients and five of these (3.5%) were positive for IgM anti-HEV and one case was positive for both. In phase II of the study, we identified a series of 168 adult patients who visited the clinic for routine medical check-up from January to April 1995 and for whom serum was collected and analyzed for liver function tests and IgG anti-HEV. Fifteen (8.9%) were positive for IgG anti-HEV. Thirty-seven (22%) of the 168 had abnormal results of liver function tests. However, abnormal liver function tests were not associated with anti-HEV IgG positivity. Anti-HAV measured in the subjects in phase II of the study showed no significant association with anti-HEV seropositivities. The prevalence of HEV infection observed in this study was much higher than reported in Japan and also higher than the Singapore host population (3.4%).