Advances in hepatitis E - I: virology, pathogenesis and diagnosis

Detection of hepatitis viruses in suspected cases of Viral Haemorrhagic Fevers in Nigeria

There have been several Viral Hemorrhagic Fever (VHF) outbreaks in Nigeria which remains a public health concern. Despite the increasing number of suspected cases of VHF due to heightened surveillance activities and growing awareness, only a few cases are laboratory-confirmed to be VHF. Routinely, these samples are only tested for Lassa virus and Yellow fever virus with occasional testing for Dengue virus when indicated. The aetiology of the disease in these VHF suspected cases in Nigeria which are negative for Lassa, Yellow fever and Dengue viruses remains a puzzle. Since the clinical features exhibited by suspected VHF cases are like other endemic illnesses such as Hepatitis, there is a need to investigate the diversity and co-infections of hepatitis viruses as differentials and possible co-morbidity in suspected cases of VHFs in Nigeria. A total of three hundred and fifty (350) blood samples of 212 (60.6%) males and 138 (39.4%) females, aged <1-70 years with a mean age of 25 ±14.5, suspected of VHFs and tested negative for Lassa, Yellow fever and Dengue viruses were investigated for Hepatitis A, B, C and E viruses at the Centre for Human and Zoonotic Virology (CHAZVY), College of Medicine, University of Lagos (CMUL) using serologic and molecular techniques. The serologic analysis of these VHF suspected cases samples revealed that 126 (36%) were positive for at least one hepatitis virus. Individual prevalence for each of the hepatitis virus screened for showed that 37 (10.6%), 18 (5.1%) and 71 (20.3%) were positive for HBV, HCV and HEV respectively. All the samples were negative for HAV. A co-infection rate of 11.9% was also observed, with HCV/HEV co-infections being the most prevalent and the Northern region having the greatest burden of infection. The evidence of hepatitis virus infections in suspected cases of VHF was documented. Thus, their associations as co-morbidities and/or mortalities in this category of individuals require further investigations in endemic countries such as Nigeria. Therefore, the possible inclusion of screening for hepatitis viruses and other aetiologic agents that could mimic infections in suspected cases of VHFs in Nigeria should be thoroughly evaluated to guide informed policy on the diagnosis and management of these cases.

Hepatitis E virus infection increases the risk of diabetes and severity of liver disease in patients with chronic hepatitis C virus infection

OBJECTIVES

Co-infection with hepatitis A or B viruses may aggravate liver injury in patients infected with hepatitis C virus (HCV). However, few studies have assessed co-infection with hepatitis E virus (HEV) and HCV. Therefore, this study aimed to assess the prevalence and impact of HEV infection among Brazilian patients with chronic HCV infection.

METHODS

This observational study included adult patients with chronic HCV infection who were naive to antiviral therapy from January 2013 to March 2016. A total of 181 patients were enrolled, and HEV serology and PCR were performed for all patients.

RESULTS

Seropositivity for anti-HEV IgG was detected in 22 (12.0%) patients and anti-HEV immunoglobulin M in 3 (1.6%). HEV RNA showed inconclusive results in nine (4.9%) patients and was undetectable in the remaining patients. HEV serology positive patients had more severe liver disease, characterized by liver fibrosis ≥3 versus ≤2 (p<0.001), Aspartate Aminotransferase-to-Platelet Ratio Index of ≥1.45 (p=0.003), and Fibrosis-4 score of ≥3.25 (p=0.001). Additionally, the odds of HEV-positive patients developing diabetes mellitus were 3.65 (95% CI 1.40-9.52) times the corresponding odds of HEV-negative patients. A case-control-based histological analysis (n=11 HEV-HCV-positive patients and n=22 HCV-positive patients) showed no significant differences between the groups.

CONCLUSIONS

This prevalence is higher than that reported in previous studies of the general population in Brazil. Thus, HEV infection may influence the severity of liver disease and may represent an additional risk of developing diabetes mellitus in patients with HCV infection.

Hepatitis E: Genotypes, strategies to prevent and manage, and the existing knowledge gaps

Hepatitis E virus (HEV) is considered an emergent source of viral hepatitis worldwide, with an increasing burden of jaundice, liver failure, extrahepatic illnesses, and deaths in developed countries. With the scarcity of data from efficient animal models, there are still open-ended questions about designing new models to study pathogenesis, types, virology, and evolution of these viruses. With an emphasis on available data and updates, there is still enough information to understand the HEV life cycle, pathogen interaction with the host, and the valuation of the role of vaccine and new anti-HEV therapies. However, the World Health Organization (WHO) and the European Association for the Study of the Liver (EASL) preferred to stress prevention and control measures of HEV infections in animals, zoonotic transmission, and foodborne transmission. It is being reviewed that with current knowledge on HEV and existing prevention tools, there is an excellent room for in-depth information about the virus strains, their replication, pathogenicity, and virulence. The current knowledge set also has gaps regarding standardized and validated diagnostic tools, efficacy and safety of the vaccine, and extrahepatic manifestations specifically in pregnant females, immunocompromised patients, and others. This review highlights the areas for more research exploration, focusing on enlisted research questions based on HEV infection to endorse the need for significant improvement in the current set of knowledge for this public health problem.

Hepatitis E: An update on One Health and clinical medicine

The hepatitis E virus (HEV) is one of the main causes of acute hepatitis and the de facto global burden is underestimated. HEV-related clinical complications are often undetected and are not considered in the differential diagnosis. Convincing findings from studies suggest that HEV is clinically relevant not only in developing countries but also in industrialized countries. Eight HEV genotypes (HEV-1 to HEV-8) with different human and animal hosts and other HEV-related viruses are in circulation. Transmission routes vary by genotype and location, with large waterborne outbreaks in developing countries and zoonotic food-borne infections in developed countries. An acute infection can be aggravated in pregnant women, organ transplant recipients, patients with pre-existing liver disease and immunosuppressed patients. HEV during pregnancy affects the fetus and newborn with an increased risk of vertical transmission, preterm and stillbirth, neonatal jaundice and miscarriage. Hepatitis E is associated with extrahepatic manifestations that include neurological disorders such as neuralgic amyotrophy, Guillain-Barré syndrome and encephalitis, renal injury and haematological disorders. The risk of transfusion-transmitted HEV is increasingly recognized in Western countries where the risk may be because of a zoonosis. RNA testing of blood components is essential to determine the risk of transfusion-transmitted HEV. There are currently no approved drugs or vaccines for HEV infections. This review focuses on updating the latest developments in zoonoses, screening and diagnostics, drugs in use and under development, and vaccines.

Hepatitis E Virus Infection and Butchers: A Case-Control Seroprevalence Study

Background

Very few case-control studies to assess the risk of hepatitis E virus (HEV) infection in meat workers have been published. Therefore, we sought to determine: 1) the association of HEV IgG seropositivity and the occupation of butcher; and 2) the sociodemographic, work, clinical and behavioral characteristics of butchers associated with HEV exposure.

Methods

We performed a case-control seroprevalence study of 101 butchers (mean age: 38.50 ± 12.52 years) and 101 age-, gender- and residence-matched control subjects of the general population. Anti-HEV IgG antibodies were determined using a commercially available enzyme-linked immunoassay. Bivariate and regression analyses were used to assess the association between HEV seropositivity and characteristics of butchers.

Results

Anti-HEV IgG antibodies were found in 18 (17.8%) of the 101 butchers and in 14 (13.9%) of the 101 control subjects (odds ratio (OR): 1.34; 95% confidence interval (CI): 0.63 - 2.88; P = 0.44). Stratification by sex, age and area of residence (rural or urban) in cases and controls showed similar seroprevalences of HEV infection among groups. Bivariate analysis showed that HEV seroprevalence was associated with low education (up to 6 years), work place, seniority, eating while working, a history of raising farm animals and national trips. However, further analysis by logistic regression showed that only the variable of national trips was associated with HEV exposure (OR: 5.38; 95% CI: 1.02 - 28.16; P = 0.04). Concerning clinical characteristics of butchers, no association between HEV exposure and health status, history of surgery or blood transfusion was found.

Conclusions

Results from this first age-, gender- and residence-matched serosurvey of HEV infection in butchers in Mexico suggest that this population group does not have a higher risk for HEV infection than people from the general population. However, further studies to confirm the lack of association between HEV infection and the occupation of butcher are needed.

Low prevalence of anti-hepatitis E virus IgG antibodies in Tepehuanos in Mexico

INTRODUCTION AND OBJECTIVE

The epidemiology of infection with hepatitis E virus (HEV) in Tepehuanos (a Mexican ethnic group living in rural areas) is largely unknown. This study aimed to determine the seroprevalence of and risk factors associated with HEV infection in Tepehuanos in Durango, Mexico, and to compare this seroprevalence with that in non-Tepehuanos.

MATERIALS AND METHODS

Through a case-control seroprevalence study, we studied 146 Tepehuanos and 146 age- and gender-matched control subjects of the general population from rural settings. The frequency of anti-HEV IgG antibodies was determined using an enzyme-linked immunoassay. Bivariate and multivariate analyses were used to assess the association between seropositivity and socio-demographic, clinical and behavioral characteristics of the Tepehuanos.

RESULTS

IgG antibodies against HEV were found in 5 (3.4%; 95% CI: 1.1-7.8) of 146 Tepehuanos and in 46 (31.5%; 95% CI: 24.1-39.7) of 146 control subjects (OR=0.01; 95% CI: 0.0007-0.20; P<0.000001). Bivariate analysis showed that HEV seropositivity was associated with age, consumption of meat from goat, sheep, boar, turkey and pigeon, and concrete flooring at home. However, these variables were no longer significant when analyzed by logistic regression.

CONCLUSIONS

This is first study on the epidemiology of HEV exposure in Tepehuanos. We demonstrated serological evidence of HEV infection in this ethnic group. The seroprevalence of HEV exposure in Tepehuanos is low as compared with that found in non-Tepehuano people living in rural Durango. Further studies to determine the risk factors associated with HEV exposure in Tepehuanos are needed.

A Review of the Diagnosis and Management of Hepatitis E

Purpose of review

We aim to provide the readers an up-to-date knowledge of the structure, epidemiology, and transmission followed by a detailed discussion on testing, diagnostics and management of hepatitis E virus infection. We have also included a comprehensive review of hepatitis E in pregnancy.

Recent findings

European Association for the Study of the Liver established clinical practice guidelines for testing and treatment of suspected hepatitis E virus infections in 2018. Evidence suggests chronic hepatitis E may follow a course similar to hepatitis B/C with progression to cirrhosis and possibly hepatocellular carcinoma in immunocompromised patients.

Summary

Hepatitis E virus is the most common cause of acute viral hepatitis worldwide. A combination of serology and nucleic acid amplification testing is the recommended strategy for suspected patients. Ribavirin therapy for a period of 3 months is the drug of choice for severe acute hepatitis, acute-on chronic liver failure, and chronic infections from hepatitis E virus in immunocompromised patients who are unresponsive to decreased immunosuppression. PEGylated interferon α can be used for ribavirin-resistant liver transplant patients with chronic hepatitis E. Further research in therapeutic options is essential considering the stormy course of hepatitis E infection during pregnancy and teratogenicity of all available options.

The First Case Report of Acute Symptomatic HEV Genotype 4 Infection in an HIV-positive Patient in Japan

Hepatitis E virus (HEV) is a common cause of acute hepatitis. Four major genotypes of HEV have been studied, with genotype 4 being the predominant genotype across Asia. We herein describe the case of a 50-year-old man with a history of human immunodeficiency virus (HIV) infection who was admitted with acute transaminitis. Serum anti-HEV-IgA and HEV-RNA were detected at the time of presentation and further testing revealed HEV genotype 4. To the best of our knowledge, this represents the first clinical case report of acute symptomatic HEV genotype 4 infection in an HIV-positive patient in Japan.

Temporal profile of HEV RNA concentration in blood and stool from patients with acute uncomplicated hepatitis E in a region with genotype 1 predominance

Acute hepatitis E virus (HEV) is associated with viremia and faecal excretion of the virus. The information on duration and temporal pattern of viremia and faecal shedding in HEV infection is important, but is not available. Serial serum and stool specimens were collected from patients with acute hepatitis E (typical clinical picture, serum alanine aminotransferase levels > 5-folds the upper limit of normal and presence of IgM anti-HEV), beginning from within 7 days of the onset of symptoms. HEV RNA concentrations were measured in sera and 10% stool suspensions, using a real-time Taqman-based nucleic acid amplification assay. Seventeen patients (median age 25 [range 19-61] years; all men) were enrolled within a median of 5 (range 3-8) days of the onset of the first symptom and provided 113 serum specimens and 71 stool specimens. The median (range) highest levels of serum bilirubin, alanine aminotransferase and aspartate aminotransferase in the patients were 10.3 (5.9-43.4) mg/dL, 1817 (442-4642) IU/L and 1016 (88-4561) IU/L, respectively. All the 17 patients had demonstrable viremia, and 12 of the 13 patients who were tested had faecal excretion at one or more time points. The HEV RNA titres were the highest in the early phase of disease and declined rapidly with time, becoming nondetectable in the serum by day 20 and in the stool by day 21. In most of the patients with acute uncomplicated acute hepatitis E, the degree of viremia and faecal shedding decline quickly after the onset of clinical illness and rapidly disappear in parallel with each other.

Hepatitis E: Epidemiology, Clinical Course, Prevention, and Treatment

Hepatitis E virus is a common cause of acute hepatitis and acute liver failure in resource-constrained parts of the world. The disease is particularly severe when the infection occurs during pregnancy. In developed countries, human infections occur primarily through zoonotic transmission from animal reservoirs; however, clinical disease is less frequent than in the developing world. The virus strains prevalent in these areas also cause chronic infection in immunocompromised persons, which, if untreated, can progress to cirrhosis; such infection responds well to oral ribavirin. A safe and highly effective recombinant vaccine is available in China, but is not available elsewhere.

Prevalence of hepatitis E viraemia among blood donors: a systematic review

BACKGROUND

Hepatitis E virus (HEV) is usually transmitted by faecal-oral route. Recent reports have documented HEV viraemia in donated blood units and HEV transmission through blood transfusion. This systematic review summarizes the available data on prevalence of HEV viraemia in blood donors.

METHODS

Electronic databases were searched on 17 December 2018 to identify full-text English papers reporting original data on prevalence of HEV RNA in donated blood units. Two authors independently extracted the relevant data, which were pooled using simple aggregation as well as a random-effects meta-analysis; heterogeneity was assessed using the I2 method.

RESULTS

In all, 59 data sets from 28 countries were identified. The available data showed marked heterogeneity. Of a total of 2 127 832 units studied, 561 (263·6 [95% confidence intervals = 242·7-286·4] per million units) tested positive for HEV RNA. On random-effects meta-analysis, the pooled prevalence was 60·9 [6·7-155·4] per million units. In the viraemic units, HEV RNA titre varied by nearly one million-fold, and most had genotype 3 HEV. The prevalence was higher in blood units with anti-HEV antibodies or elevated alanine aminotransferase. Only nearly one-fourth of viraemic units had anti-HEV antibodies.

CONCLUSIONS

The prevalence of HEV viraemia among healthy blood donors is low, though the available data had limited geographical representation and marked heterogeneity. There is a need for further data on HEV viraemia in blood donors from areas with non-3 HEV genotype preponderance.

Blood transfusion is unlikely to be a source for hepatitis E virus transmission in India

INTRODUCTION

Transmission of hepatitis E virus (HEV) through transfusion has been reported from countries where genotype 3 virus is predominant. Data from countries with predominantly genotype 1 HEV, such as India, are limited. We studied the risk of HEV transmission following transfusion of blood or blood components in India.

METHODS

Adult patients undergoing cardiac surgery who received transfusion of blood or blood products in the peri-operative period and who lacked history of any transfusion or surgery in the preceding 1 year were studied. A pre-transfusion blood specimen was collected for IgG anti-HEV antibody test. For the participants who were seronegative for anti-HEV, follow up specimens were collected at every 2-3-month intervals for up to 6 months after surgery and were tested for IgM and IgG anti-HEV antibodies.

RESULTS

Of the 335 participants originally enrolled, 191 (57%) could be followed up. Of them, 103 (53.9%) were seropositive for HEV IgG at baseline and were excluded. Of the remaining 88 participants (age 42 ± 14.1 years; 55 [63%] male), none reported hepatitis-like illness during the follow up period of 81 ± 23 days. Also, none of these 88 participants was found to have seroconversion to anti-HEV IgM or IgG positivity in the follow up specimens.

CONCLUSION

Transfusion-mediated transmission of HEV was not observed in our cohort and may be infrequent in the Indian population, where genotype 1 is the predominant HEV type.

Natural History, Clinical Manifestations, and Pathogenesis of Hepatitis E Virus Genotype 1 and 2 Infections

Infection with genotype 1 or 2 hepatitis E virus (HEV) results primarily from human-to-human transmission through the fecal-oral route in low-resource countries. It presents primarily as "acute viral hepatitis" syndrome, usually a self-limiting illness. A few cases progress to acute liver failure, a serious illness with high fatality. Clinical disease is infrequent among children. Infection during pregnancy is associated with a higher risk of symptomatic disease, severe liver injury, and mortality. Severe disease is also encountered in persons with preexisting chronic liver disease. Some cases have associated extrahepatic features, particularly acute pancreatitis and neurological manifestations. Chronic infection appears to be extremely infrequent with these HEV genotypes. The exact pathogenesis of liver injury remains unknown, although the host immune response appears to be important for viral clearance as well as for induction of liver injury. Hormonal and immune factors appear to be responsible for the severe disease during pregnancy.

A guide to the management of hepatitis E infection during pregnancy

Hepatitis E virus (HEV) infection has distinct features, depending upon the genotype and geographical area. HEV genotypes 1 and 2 are endemic to various developing countries causing epidemics of acute viral hepatitis with human to human transmission. On the other hand, HEV genotypes 3 and 4 prevalent in developed countries commonly lead to subclinical infection and are transmitted zoonotically. HEV infection typically causes acute self-limiting illness associated with low morbidity and mortality. Infection with HEV genotype 1 or 2 in pregnancy, especially in the third trimester may lead to severe illness and fulminant liver failure. Poor maternal and fetal outcomes have been reported. Areas covered: This review highlights the various aspects of HEV infection in pregnancy including diagnosis, management, and prevention. Expert commentary: Treatment is mainly supportive with diligent monitoring and intensive care. Therapeutic termination of pregnancy cannot be recommended based to the available literature. Early liver transplantation (LT) should be considered in these patients although the indications and timing of LT are still controversial. Prevention of HEV infection or illness by improved sanitation and active/passive immunization needs further research.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Disparities in detection of antibodies against hepatitis E virus in US blood donor samples using commercial assays

BACKGROUND

Reported hepatitis E virus (HEV) antibody assay performance characteristics are variable. Using a subset of surplus US blood donation samples, we compared assays for detecting anti-HEV immunoglobulin M (Ig)M and IgG or total anti-HEV antibodies.

STUDY DESIGN AND METHODS

Samples from 5040 random blood donations, all HEV-RNA negative, collected primarily in the midwestern United States in 2015 were tested for anti-HEV IgM and IgG or total anti-HEV using assays manufactured by Diagnostic Systems, Wantai, and MP Biomedicals.

RESULTS

Overall, the percentage of detection for anti-HEV IgG and total anti-HEV was 11.4%, and for anti-HEV IgM was 1.8%. Nine samples were reactive for anti-HEV IgM by all assays, giving a recent infection rate of 0.18%. Anti-HEV IgG/total anti-HEV detection rates increased with age. Interassay agreement was higher among the IgG anti-HEV/total anti-HEV assays (84%) than the IgM assays (22%). Regression analyses of signal-to-cutoff ratios from IgG/total antibody assay were heteroskedastic, indicating no constant variance among these assays, suggesting they may detect different epitopes or were affected by waning or less avid antibodies in the US donor population.

CONCLUSIONS

Although similar percentages of IgG anti-HEV/total anti-HEV detection were observed across the three commercial assays, each assay detected a unique sample subpopulation and was heteroskedastic when compared pairwise. Discordance was higher among anti-HEV IgM assays, but a recent HEV infection rate of at least 0.18% was estimated based on assay concordance.

Laboratory challenges in the diagnosis of hepatitis E virus

Hepatitis E virus (HEV) is an RNA virus that is an important cause of both acute and chronic hepatitis worldwide. To date, there are eight HEV genotypes that can infect mammals. HEV-1 and HEV-2 infect exclusively humans, while HEV-3 and HEV-4 infect humans and various animals, mainly pigs and deer. Additionally, two new genotypes (HEV-5 and HEV-6) infect mainly wild boar. Recently, newly discovered genotypes HEV-7 and HEV-8 were found to infect camels and possibly humans. Nevertheless, the epidemiological distribution of HEV-7 is not well established. HEV-8 is another newly discovered genotype that was identified in 2016 in Chinese Bactrian camels. Although faecal-oral transmission is the most common route of HEV transmission, HEV can be vertically transmitted from infected mothers to their fetuses. HEV may also spread by zoonotic transmission from infected animals to humans and through person-to-person contact. Nowadays, since the number of reported cases linked to blood donations is increasing annually, HEV is recognized as a transfusion-transmitted virus. Laboratory diagnostic techniques vary in their specificity and sensitivity for HEV detection. Direct techniques allow for detection of the viral proteins, antigens and viral nucleic acid, while HEV-specific IgG and IgM antibodies can help establish a diagnosis in acute and chronic infections. In this review, we will discuss recent technologies in the laboratory diagnosis of HEV, including serological and molecular methods to assess the specificity and sensitivity of currently available HEV commercial assays.

Acute hepatitis E in India appears to be caused exclusively by genotype 1 hepatitis E virus

BACKGROUND

Hepatitis E is caused by infection with hepatitis E virus (HEV), which has four well-known genotypes. Genotypes 1 and 2 HEV have been reported from human cases in areas where the disease is highly endemic. By contrast, genotypes 3 and 4 HEV, which primarily infect several animal species worldwide, have been reported mainly from sporadic human cases in non-endemic areas such as Japan and high-income countries of Europe and North America. To determine whether genotype 3/4 HEV cause sporadic disease in India, a disease-endemic area, we determined HEV genotype in a group of patients with such disease.

METHODS

A part of the HEV open reading frame (ORF) 1 was amplified and sequenced from sera of 74 patients with sporadic acute viral hepatitis E from four cities in India. The sequences were compared with prototype sequences for various HEV genotypes and subgenotypes and analyzed using phylogenetic tools to determine the genotype of the isolates. For 12 specimens, a part of HEV ORF2 was also similarly analyzed.

RESULTS

Partial ORF1 sequences of all the 74 isolates belonged to genotype 1 HEV, with 88.2% to 100% nucleotide identity with the prototype genotype 1 isolates. Partial ORF2 sequences for all the 12 isolates also belonged to genotype 1 HEV. On phylogenetic analysis, 71 isolates clustered with prototype genotype 1a HEV; the remaining three isolates were located between subgenotypes 1a and 1c but were closer to the former.

CONCLUSION

Human sporadic acute hepatitis E in India is caused almost exclusively by genotype 1 HEV.

Hepatitis E and pregnancy: current state

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.

Advances in hepatitis E - II: Epidemiology, clinical manifestations, treatment and prevention

INTRODUCTION

Infection with hepatitis E virus (HEV) is the commonest cause of acute hepatitis worldwide. This infection, with fecal-oral transmission, was previously thought to be limited to humans residing in developing countries with poor sanitation, spreading via contaminated drinking water. In recent years, our understanding of epidemiology and clinical spectrum of this infection have changed markedly.

AREAS COVERED

This article reviews the epidemiology, including routes of transmission, and clinical manifestations of HEV infection around the world. In addition, recent findings on transmission-associated HEV infection, extrahepatic manifestations of hepatitis E and chronic infection with HEV, and treatment and prevention of this infection are discussed. Expert commentary: HEV infection has two distinct epidemiologic forms and clinical patterns of disease: (i) acute epidemic or sporadic hepatitis caused by fecal-oral (usually water-borne) transmission of genotype 1 and 2 HEV from a human reservoir in areas with poor hygiene and frequent water contamination, and (ii) infrequent sporadic hepatitis E caused by zoonotic infection, possibly from an animal source through ingestion of undercooked animal meal, of genotype 3 or 4 virus. In disease-endemic areas, pregnant women are at a particular risk of serious disease and high mortality. In less-endemic areas, chronic infection with HEV among immunosuppressed persons is observed. HEV can also be transmitted through Transfusion of blood and blood products. Ribivirin treatment is effective in chronic hepatitis E. Two efficacious vaccines have been tried in humans; one of these has received marketing approval in its country of origin.