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 of the infection is presumed to be low. Methods: Between 2014 and 2016, we recruited individuals from Iwate Prefecture, Japan, who visited a general medical workup program. Serum anti‐HEV antibody and HEV RNA were measured twice with an interval of two years. Anti‐HEV antibody was measured with enzyme‐linked immunosorbent assay and HEV RNA with RT‐PCR. Results: Study participants comprised 1,284 Japanese (650 males and 634 females) with age ranging 20–89 years. Ninety participants were found to be positive for anti‐HEV IgG on the first visit with a prevalence of 7.0% (95% confidence interval [CI]; 5.6–8.4%). Seroprevalence was higher in males than in females (10.1% vs. 3.7%, p<0.001), and in those in their 50s–80s than in those in their 20s–40s (p=0.006). Positive seroconversion indicating new HEV infection was found in seven of 1,194 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.

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