Hepatitis E virus (HEV) is yearly responsible for approximately 20 million infections worldwide.
Although most infections occur in developing countries, HEV appears to be an emerging
problem in several industrialized countries, where it is mostly associated with either
traveling to an HEV endemic area or contact with pigs, which represent a major reservoir of
HEV. The major risk groups for HEV infection and its ensuing complications are elderly
men, pregnant women, young children, immunocompromised patients, patients with preexisting
liver disease, and workers that come into close contact with HEV-infected animals.
Whereas HEV mainly causes acute self-limiting infections, chronic infections may occur
among immunocompromised patients (e.g., transplant recipients and human immunodeficiency
virus [HIV]-infected patients). Accordingly, HEV-HIV coinfection leads to accelerated
liver cirrhosis and increased mortality rates compared to HEV infection alone, which is,
except during pregnancy, usually associated with only low mortality. In the Western world,
the most common genotype (gt) causing HEV infection is gt 3. Ribavirin (RBV) and interferon
have been used successfully for treatment of HEV, but this treatment is contraindicated
in certain patient groups. Therefore, novel antiviral compounds are highly needed, especially
given that viral isolates with RBV resistance have been recently identified. Moreover, eradication
of HEV is hampered by long-term environmental persistence of the virus, which represents
a continuous source of the virus. In 2011, the first prophylactic HEV vaccine, Hecolin,
was approved in China, but it is not yet globally available. In this review, we will discuss the
molecular virology of HEV, mode of transmission in industrialized countries, and potential
implications for different specific patient populations. (HEPATOLOGY 2015;62:1883-1892)