Prevalence and Phylogenetic Analysis of Hepatitis E Virus among Pigs in Japan

Abstract

The number of reported cases of human hepatitis E virus (HEV) infection has increased since 2012. Pigs are considered an important source of viruses causing human HEV infection. It is possible that the prevalence of HEV among pigs at slaughter age (approximately 6 months old) has increased in the last decade. Therefore, we investigated the current prevalence of HEV among pigs in Japan. Although HEV RNA was detected in rectal content samples from pigs aged from one to 5 months, no HEV RNA was detected in any samples from 6-month-old pigs. The highest viral shedding prevalence (33%) was detected among 3-month-old pigs. This study shows that there has been no change in the prevalence of HEV among pigs at the slaughter age, in the prevalence of HEV by age group on pig farms, or in the phylogenetic classification of HEV isolates in the last decade. Therefore, factors downstream of the pork production stage may be contributing to the increased number of human HEV infection cases.