Seroprevalence and incidence of hepatitis E virus infection in the general population of Iwate prefecture, Japan: A retrospective cohort study.

Aim: Hepatitis E virus (HEV) causes subclinical or acute self‐limiting hepatitis. We surveyed the current seroprevalence and incidence of HEV infection among the general population in Iwate Prefecture, Japan, where the endemic infection is presumed to be low. Methods: Between 2014 and 2016, we recruited individuals from Iwate Prefecture, Japan, who visited a general medical work‐up program. Serum anti‐HEV antibody and HEV RNA were measured twice, with an interval of 2 years. Anti‐HEV antibody was measured with enzyme‐linked immunosorbent assay and HEV RNA with reverse transcription‐polymerase chain reaction. Results: Study participants comprised 1284 Japanese (650 men and 634 women) with age ranging 20–89 years. A total of 90 participants were found to be positive for anti‐HEV immunoglobulin G on the first visit, with a prevalence of 7.0% (95% confidence interval [CI] 5.6%–8.4%). Seroprevalence was higher in men than in women (10.1% vs. 3.7%, p < 0.001), and in those aged in their 50s–80s than in those aged in their 20s–40s (p = 0.006). Positive seroconversion indicating new HEV infection was found in seven of 1194 seronegative participants (0.59%; 95% CI 0.15%–1.0%), indicating the incidence of HEV infection to be 272 per 100 000 person‐years (95% CI 109–561). Conclusions: Our observations suggest that the incidence of HEV infection is high and that it is a leading cause of hepatitis virus infection in Iwate Prefecture, Japan. [ABSTRACT FROM AUTHOR]