Changing clinical and molecular characteristics of hepatitis E virus infection in Mie Prefecture, Japan: Disappearance of indigenous subtype 3e strains

Abstract

Aim To evaluate the clinical and molecular characteristics of hepatitis E virus (HEV) infection in Mie Prefecture, Japan, from 2004 through 2018. Methods The clinical information of hepatitis E cases was collected from 21 medical institutions in Mie Prefecture. The nucleotide sequences of infecting HEV strains were determined for cases with available serum samples. The origins or transmission routes were inferred from phylogenetic analyses of the nucleotide sequences. Results Fifty‐three patients were diagnosed with HEV infection. The number of cases increased each year through 2012 and then decreased. Analyses of the clinical characteristics of the cases indicated that even mild cases were detected in the latter 10 years of the study. Nucleotide sequence analyses were undertaken on 38 of the 53 cases. The HEV subtype 3e (HEV‐3e) strains identified for 13 cases were closely related to a swine HEV‐3e strain that was isolated from the liver of a pig bred in Mie Prefecture. The number of cases infected with the indigenous Mie HEV‐3e strains increased until 2012 but have not been reported since 2014. In the latter half of the study, cases involving various HEV strains of different genotypes and subtypes emerged. Conclusions The disappearance of indigenous Mie HEV‐3e strains appeared to be the primary cause for the decrease in hepatitis E cases in Mie Prefecture. The disappearance might have been associated with improved hygienic conditions on pig farms or the closure of contaminated farms. The results suggest that indigenous HEV strains can be eradicated by appropriate management.

Clinical and virologic features of hepatitis E virus infection at a university hospital in Japan between 2000 and 2019

“…Because an HEV examination is not required before the shipment of animal meat/viscera, we have a risk to contract HEV infection. The number of patients with acute hepatitis E decreased in Mie prefecture where HEV GT3e was a major GT in HEV infection 9 . This is probably due to the decreased number of pig farms in Mie prefecture where the HEV GT3e strain was isolated from the pigs bred on the farms.…”

“…These nucleotide sequence analyses of HEV provided us further information on the features of HEV. For instance, an HEV strain isolated from patients in Mie prefecture was closely associated with the strain isolated from pigs bred in the same prefecture 9 …”

“…We need to interview for identification of other causes of HEV. Furthermore, indigenous HEV strains were isolated in other areas of Japan, 9,13 which caused HEV infection in their areas.…”

Time course alterations of virus sequences and immunoglobulin titers in a chronic hepatitis E patient

“…Recently, the numbers of hepatitis E cases have increased in developed countries . HEV infects hosts through water, game meat, and blood transfusion . Fulminant hepatitis, chronic hepatitis, and extrahepatic manifestations are serious problems involving HEV infection …”

“…The initial management for chronic infection is to reduce immunosuppressive therapy leading to the elimination of HEV in approximately 30% of patients . Alternatively, treatment with ribavirin (RBV) is effective . Recently, several mutations of HEV were detected in RBV treatment failure patients .…”