Current issues in hepatitis E: an overview

Abstract

Of the five recognized classical hepatitis
viruses, hepatitis E virus (HEV) remains
an important etiological agent of acute and
chronic hepatitis as well as extrahepatic
symptoms [1–5]. HEV infection accounts
for a global mortality rate of approximately
2% that includes fulminant liver failure in
about 30% of pregnant women [6, 7]. As per
the recent consensus classification of the
hepatotropic viruses, HEV is categorized
as a member of the species Orthohepevirus
A within the genus Orthohepevirus of
family Hepeviridae [8]. Further, of the
eight identified genotypes of HEV (HEV1-
HEV8), HEV1-HEV4 are known to infect
humans [8]. While HEV1 transmission is
associated with waterborne outbreaks in
underdeveloped or developing countries,
HEV3 and HEV4 transmission is foodborne,
potentially linked to zoonosis in swine and
other mammals in industrialized nations
[9]. Nonetheless, epidemiology of HEV3
is rather complex because of its hitherto
well recognized sources and routes of
transmission. Moreover, while HEV1 causes
self-limiting acute infection in general
population, HEV3 takes a chronic course
in clinically immunocompromised patients
[3]. Also, as compared to HEV1 associated
pregnancy complications in general, there
are limited case reports of HEV3 infection in
pregnant women [10].