The seroprevalence of anti-hepatitis E virus (HEV) antibody in developed countries ranges from 0.5–25%, suggesting high numbers of subclinical or unrecognized infections. Several reports of autochthonous (locally acquired) cases in the UK, France, Holland and Japan have established that hepatitis E in developed countries is more common than previously thought.

Dalton et al. studied cases of autochthonous hepatitis E in southwest England. Hepatitis E cases were identified by testing of samples from patients with unexplained hepatic illness. Over seven years, 333 patients were tested for HEV IgG, IgM and reactive serum samples were tested for HEV RNA by reverse transcriptase–polymerase chain reaction (RT–PCR). Patients also completed a detailed questionnaire including specific questions on travel, location of dwelling, dietary history and details of contact with animals.

Hepatitis E was identified in 21 Caucasian patients, 20 of whom presented between March and October. All 16 RT–PCR positive samples were sequenced and found to be genotype three, showing close homology to HEV found in the UK pig herd.

Currently, the source of autochthonous hepatitis E in developed countries is unknown. One possibility is that it may be due to zoonotic infection from pigs, as herds worldwide are known to have a high HEV seroprevalence (UK estimated at 85%). Also, there is a high anti-HEV seroprevalence in pig handlers or veterinarians caring for pigs. Finally, the genome sequence of HEV in human and pigs show close sequence homology. The genomic sequences of the reported cases were similar but not identical, suggesting infection from numerous sources. Although Cornwall and Devon are farming areas, little is with pigs, making contamination from faeces very unlikely. A more probable source is from HEV contaminated meat; however, it is unknown if HEV can infect the human food chain.

Dalton et al. propose that more nationwide testing needs to be done in order to determine the incidence of autochthonous hepatitis E. They also recommend all patients with acute hepatic illness are tested for HEV, whatever their age or travel history.