Hepatitis E in New Zealand

Abstract

Locally acquired hepatitis E virus (HEV) infection has been described in a number of developed countries and is thought to be zoonotic from pigs. Little is known about hepatitis E in humans in New Zealand (NZ) but 90% of NZ pigs show evidence of HEV infection. The aim of this study was to investigate the epidemiology of hepatitis E infection in NZ by documenting HEV immunoglobulin (Ig) G seroprevalence in NZ blood donors, testing patients with unexplained hepatitis for HEV, and comparing genetic sequences of human HEV with local porcine isolates. In total, 265 blood donors were tested for HEV IgG and 77 patients with unexplained hepatitis were tested for HEV. Viral sequences were compared with known HEV isolates including those from NZ pigs. The HEV IgG seroprevalence was 4%. HEV genotype 3 was isolated in four patients with unexplained hepatitis. Clinical and sequencing data suggest that two cases were acquired in Europe and two in NZ. All cases were in elderly patients, one of whom was asymptomatic and initially misdiagnosed as a drug reaction. The NZ-acquired cases were most similar to HEV from Japan, and bore little sequence homology to HEV isolated from NZ pigs. Hepatitis E does occur in NZ in patients who have not traveled to endemic areas and seems to affect the elderly. The seroprevalence data suggest that subclinical/unrecognized infection is common. Sequencing data suggest that some reservoir other than pigs could be the source of HEV in NZ. It is recommend that all patients with unexplained hepatitis, whatever their age or travel history, are tested for HEV.