Hepatitis E: An overview and recent advances in clinical and laboratory research

Abstract

Hepatitis E virus (HEV) is a non-enveloped RNA (7.5 kb) virus that is responsible for large epidemics of acute hepatitis and a proportion of sporadic hepatitis cases in southeast and central Asia, the Middle East, parts of Africa and Mexico. Hepatitis E virus infection spreads by the faecal-oral route (usually through contaminated water) and presents after an incubation period of 8-10 weeks with a clinical illness resembling other forms of acute viral hepatitis. Clinical attack rates are the highest among young adults. Asymptomatic and anicteric infections are known to occur. Chronic HEV infection is not observed. Although the mortality rate is usually low (0.07-0.6%), the illness may be particularly severe among pregnant women, with mortality rates reaching as high as 25%. Recent isolation of a swine virus resembling human HEV has opened the possibility of zoonotic HEV infection. Studies of pathogenetic events in humans and experimental animals reveal that viral excretion begins approximately 1 week prior to the onset of illness and persists for nearly 2 weks; viraemia can be detected during the late phase of the incubation period. Immunoglobulin M antibody to HEV (anti-HEV) appears early during clinical illness but disappears rapidly over a few months. Immunoglobulin G anti-HEV appears a few days later and persists for at least a few years. There is no specific treatment available for hepatitis E virus infection. Ensuring a clean drinking water supply remains the best preventive strategy. Recombinant vaccines are being developed that may be particularly useful for travellers to disease-endemic areas and for pregnant women.

A 20-year single-center experience with acute liver failure during pregnancy: Is the prognosis really worse?

“…However, there is some evidence that acute hepatitis caused by HEV may be particularly severe among pregnant women and girls, with mortality rates reaching 15% to 20%. 25 In prospective studies evaluating pregnant patients with acute hepatitis caused by HEV, progression to ALF has been reported in 15% to 60% of patients. [26][27][28][29] In two prospective, comparative studies from Kashmir and Delhi, 55% to 70% of pregnant women and girls with HEV hepatitis compared with 10% to 20% of pregnant women and girls with non-HEV hepatitis progressed to liver failure.…”

Endemic hepatitis E in two Nordic countries

“…However, in our study HEV RNA was also detected in 18% of sera from patients with anti-HEV IgG only, which is an unexpectedly high frequency and has not been described earlier, since the presence of IgG in the absence of detectable IgM is considered a marker of past infection. Anti-HEV IgG may persist for several years after infection, but whether lifelong immunity is conferred remains uncertain [24]. There is only one serotype of HEV, but it is not known if reinfections induce IgG response only or if also the IgM levels become elevated.…”

Hepatitis E virus in humans, farm animals and animals from the sylvatic environment

“…Charakterystycznym objawem jest żółtaczka, której towarzyszą: złe samopoczucie, gorączka, bóle stawów, nudności, wymioty, ból brzucha i biegunka. Objawy na ogół ustępują samoistnie po 7-28 dniach, natomiast siewstwo wirusa w kale zwykle trwa do 4 miesięcy od wystąpienia pierwszych objawów choroby (1,62). Przeciwciała anty-HEV IgM pojawiają się wraz z wystąpieniem objawów klinicznych zakażenia i po około 4-5 miesiącach stopniowo zanikają wraz z pojawieniem się przeciwciał klasy IgG (1).…”