Hepatitis E Virus (HEV) - An Emerging Viral Pathogen

Hepatitis E virus (HEV) is the second major etiologic agent of enterically transmitted non-A, non-B hepatitis worldwide. HEV is an unenveloped, single-stranded RNA virus having genome of approximately 8 kb in size. It is the sole member of the genus Hepevirus in the family of Hepeviridae. Although it is most commonly recognised to occur in large outbreaks, HEV infection accounts for > 50% of acute sporadic hepatitis in both, children and adults in some high endemic areas as Northern Africa and most of Asia. Whereas it was long believed that it is prevalent in the areas where hygiene standards are poor, HEV is expected in non-endemic countries as well. Although HEV is mainly transmitted via the faecal-oral route, a high potential exist for water and foodborne transmission, parenteral and perinatal routes. Person to person contact have been implicated. Cases of acute hepatitis of novel HEV variants have been reported in humans in Europe, Japan and USA, showing that HEV is not limited or geographically distributed. Recently an avian HEV was found to be transmitted via the egg yolk. HEV infection can lead to deadly hepatic failure in 1-4% in the common population, but the mortality incidence reaches 0.5-3% among young adults and 15-20% among pregnant women. A chronic infection has developed in patients with liver transplants and in immune compromised people. Due to the lack of practical models for HEV, the mechanisms of HEV pathogenesis and replication are still not well understood. The diagnosis of HEV infection can be made using serological tests but still, RT-PCR is considered as the gold standard. Up to date, no treatment for HEV is available, but recently, a new vaccine, ending the phase 2 trials has showed promising outcomes. Here, we discuss the current knowledge on the molecular biology, pathology, clinical features, transmission, diagnosis, epidemiology, and prevention of HEV.