Hepatitis E virus (HEV) is responsible for more than 50% of acute viral hepatitis cases in endemic countries. Approximately 2 billion individuals live in hepatitis E-endemic areas and, therefore, are at risk of infection. According to World Health Organization, HEV causes about 20.1 million infections and 70 000 deaths every year. In developing countries with poor sanitation, this disease is transmitted through contaminated water and is associated with large outbreaks, affecting hundreds or thousands of people. In developed countries, autochthonous cases of HEV have been increasingly recognized in the past several years. Hepatitis E virus typically causes an acute, self-limiting illness similar to other acute viral hepatitis, such as hepatitis A or B, with about 0.2% to 1% mortality rate in the general population. However, the course of hepatitis E in pregnancy is different than the mild self-constraining infection described in other populations. During pregnancy, HEV infection can take a fulminant course, resulting in fulminant hepatic failure, membrane rupture, spontaneous abortions, and stillbirths. Studies from various developing countries have shown a high incidence of HEV infection in pregnancy with a significant proportion of pregnant women progressing to fulminant hepatitis with a fatality rate of up to 30%. The present review will highlight new aspects of the HEV infection and pregnancy.

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Although only a single serotype of hepatitis E virus (HEV), the causative agent of hepatitis E, has been identified, there is great genetic variation among the different HEV isolates reported. There are at least four major recognized genotypes of HEV: genotypes 1 and 2 are mainly restricted to humans and linked to epidemic outbreaks in nonindustrialized countries, whereas genotypes 3 and 4 are zoonotic in both developing and industrialized countries. Besides human strains, genotype 3 and 4 strains of HEV have been genetically characterized from swine, sika deer, mongooses, sheep, and rabbits. Currently, there are approximately 11,000 human and animal sequences of HEV available at the International Nucleotide Sequence Database Collaboration. HEV is the major cause of waterborne outbreaks of hepatitis in areas of poor sanitation. Additionally, it is responsible for sporadic cases of viral hepatitis in not only endemic but industrialized countries as well. Transmission of HEV occurs predominantly by the fecal-oral route, although parenteral and perinatal routes have been reported. HEV infection develops in most individuals as a self-limiting, acute, icteric hepatitis; with mortality rates around 1%. However, some affected individuals will develop fulminant hepatic failure, a serious condition that is frequently fatal without a liver transplant. This complication is particularly common when the infection occurs in pregnant women, where mortality rates rise dramatically to up to 25%. Among the preventive measures available to avoid HEV infection, two separate subunit vaccines containing recombinant truncated capsid proteins of HEV have been shown to be highly effective in the prevention of disease. One of them, HEV 239, was approved in China, and its commercialization by Innovax began in November 2012 under the name Hecolin®.

Hepatitis E virus is responsible for sporadic cases of acute, self-limited viral hepatitis not only in endemic but also in industrialized countries. In addition, some reports confirm that it can cause chronic infection and even cirrhosis in immunosuppressed and also in patients infected with HIV. There are few data about prevalence and incidence of HEV chronic infection in HIV-HEV coinfected individuals in Spain. The aim of this study is to investigate the prevalence of anti-HEV IgG in a representative sample of 448 patients infected with HIV and determine the role of age, gender, and CD4 counts in the detection of anti-HEV IgG antibodies in blood. In addition, the clinical features and ALT levels in relation to the presence of anti-HEV IgM and/or HEV-RNA in the blood of these patients were investigated. Anti-HEV IgG antibodies were detected in serum using a commercial enzyme immunoassay. All positive samples were studied further for the presence of anti-HEV IgM antibodies. In addition, HEV RNA was amplified by reverse transcriptase (RT)-nested PCR in all serum samples with IgM anti-HEV. The overall prevalence of anti-HEV IgG was 10.4% (45/448, 95% C.I. 7.2-12.8%). HEV-RNA was found in only one patient out of the 45 anti-HEV IgG positive samples studied. Regarding to gender and CD4 count, no difference in seroprevalence could be observed. This prevalence data suggest that patients infected with HIV can be considered a risk group for HEV infection and that chronic coinfection HEV-HIV seems to be a very rare event.

Hepatitis E, caused by Hepatitis E virus (HEV), is a highly prevalent disease in developing countries. In developed nations, autochthonous HEV infections seem to be an emergent disease. Its clinical manifestations and epidemiology are well known for endemic countries. It has been confirmed that hepatitis E is a zoonosis and that parenteral transmission can also occur. The molecular mechanisms of HEV replication are not fully understood, mostly because there are no efficient cell culture systems. HEV can cause chronic hepatitis in organ transplant recipients and immunocompetent patients. Cases with fulminant hepatitis and other extrahepatic manifestations have also been reported. The diagnosis is based on serological studies and detection of HEV RNA in blood and feces. Treatment with ribavirin and/or pegylated-IFN-α have proven to be successful in some cases. The recently approved/marketed vaccine is a good option in order to prevent this infection.