Characterisation of the increasing numbers of autochthonous hepatitis E infections in England and Wales 2010-2015

      Purpose: Hepatitis E virus (HEV) was previously known for causing acute infections in travellers returning from hyper-endemic countries. However, autochthonous, food –borne transmission of HEV genotype 3 (GT3) has been increasingly recognized as an emerging problem in industrialized countries. Although asymptomatic in most cases, HEV GT3 can cause mild and self-limiting to severe acute hepatitis and, most worryingly, chronic hepatitis in immunocompromised patients. Over the last decade, cases of acute HEV infection in humans have been increasing across Europe. Since 2010, a year on year increase has been reported in England and Wales. Previously the only phylotype circulating in England and Wales was HEV GT3 group 1, however, the substantial increase in HEV cases since 2010 has been associated with the emergence of a novel group of the virus (HEV GT3 group 2). Enhanced surveillance of cases of acute HEV infections in England and Wales was established in 2005 to investigate and characterise non-travel associated cases of HEV and to identify potential risk factors.
      Methods & Materials: Newly diagnosed cases of HEV are reported to the Second Generation Surveillance System (SGSS, a voluntary electronic reporting database of clinically significant pathogens by NHS hospital laboratory departments). In addition, Health Protection Teams across England and Wales also report new cases of HEV and complete an enhanced surveillance questionnaire on each case. For case ascertainment, these findings are compared with cases reported to SGSS.
      Results: The number of HEV cases tripled from 2010 to 2015. As previously reported, the majority (>70%) of cases of HEV GT3 infections are male and their median age is above 60 years. HEV GT3 group 2 virus appears to be responsible for a large part of the increase in indigenous cases, whilst a trend towards more severe and prolonged illness has been observed in cases of HEV GT3 clade 1 as demonstrated through higher rates of hospital admissions and prolonged illness.
      Conclusion: The increasing rates of HEV across England and Wales remain a concern, particularly as the natural history of this disease continues to be unclear. The emergence of a new phylotype largely responsible for the increase in cases warrants further research.