Virology

HEV is a small non-enveloped, single-stranded RNA virus approximately 27-34 nm in diameter with a genome that is approximately 7.2 kb in length. It is the only member in the Hepeviridae family and is closely related to members of the Calicivirus family.^[1] HEV was previously known as enterically-transmitted non-A, non-B hepatitis.^[2] There are four recognised genotypes, which fall into two groups. Genotypes 1 and 2 are confined to humans and cause epidemic hepatitis associated with faecal-oral transmission while genotypes 3 and 4 are swine viruses which are common in domestic and wild pigs and infect humans as an accidental host and therefore are considered as zoonoses.^[3]