Hepatitis E vaccine-Illuminating the barriers to use

Hepatitis E Virus in the Role of an Emerging Food-Borne Pathogen

Viral hepatitis E represents an important global health problem caused by the hepatitis E virus (HEV). Cases of HEV infection are increasingly associated with food-borne transmissions after the consumption of raw or undercooked food products from infected animals in high-income regions. Although most cases of infection are asymptomatic, severe courses of infection have been reported in specific groups of people, predominantly among pregnant women and immunocompromised patients. The viral nucleic acid of HEV is increasingly being reported in food-producing animals and different products of an animal origin. Even though the incubation period for HEV infection is long, several direct epidemiological links between human cases and the consumption of HEV-contaminated meat and meat products have been described. In this article, we review the current knowledge on human HEV infections, HEV in different food-producing animals and products of an animal origin, as well as the accumulation and resistance to HEV in farm and slaughterhouse environments. We also provide preventive measures to help eliminate HEV from animals, the human population, and the environment.

[Hepatitis E: Epidemiology, pathology and prevention]

Hepatitis E virus (HEV) is a major cause of acute hepatitis. HEV genotypes 1 and 2 are associated with oro-faecal epidemics and fulminant hepatitis in pregnant women. HEV genotypes 3 and 4 are a zoonosis transmitted by uncooked pork. Infection is usually spontaneously resolutive. Chronic hepatitis may occur in immunocompromised patients. Extrahepatic disease is also possible. Prevention is based on hygiene, especially in high-risk patients, and access to safe drinking water for all. A recombinant vaccine against HEV has been developed and is currently being validated by the WHO.

The Use of Residual Blood Specimens in Seroprevalence Studies for Vaccine-Preventable Diseases: A Scoping Review

Background: Residual blood specimens offer a cost- and time-efficient alternative for conducting serological surveys. However, their use is often criticized due to potential issues with the representativeness of the target population and/or limited availability of associated metadata. We conducted a scoping review to examine where, when, how, and why residual blood specimens have been used in serological surveys for vaccine-preventable diseases (VPDs) and how potential selection biases are addressed. Methods: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines and identified relevant papers published in 1990-2022. Results: A total of 601 articles met the inclusion criteria after title, abstract screening, and full-text review. The most studied VPDs using residual blood specimens were COVID-19 (27%), hepatitis E (16%), hepatitis B (10%), influenza (9%), HPV (7%), and measles (7%). Residual blood specimens were primarily sourced from diagnostic specimens (61%) or blood and plasma donations (37%). Almost all articles used specimens linked to basic demographic data (e.g., age and sex), with 47% having access to extended demographic data (e.g., geographic location). Common strategies to address potential biases included comparing results with published estimates (78%) and performing stratified analyses (71%). Conclusions: Residual blood specimens are widely used in seroprevalence studies, particularly during emerging disease outbreaks when rapid estimates are critical. However, this review highlighted inconsistencies in how researchers analyze and report the use of residual specimens. We propose a set of recommendations to improve the analysis, reporting, and ethical considerations of serological surveys using residual specimens.

Molecular epidemiology of Hepatitis E virus among humans in the Niger Republic, 2017-2023

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis, responsible for large outbreaks in resource limited countries. The virus belongs to the genus Orthohepevirus which is subdivided into eight distinct genotypes (HEV-1 to HEV-8). Human disease transmission is mostly through the faecal-oral route. However, zoonotic transmission could also occur. In the Niger Republic, the first documented HEV outbreak was recorded in 2017 around displaced persons camps in the Diffa region across the Lake Chad basin, resulting in 736 confirmed cases and 38 (1.9%) deaths. Since then, sporadic cases were annually reported despite the lack of specific surveillance. Overall, from 2017 to 2023, a total of 2820 HEV suspected cases were sampled, out of which 906 (32.12%) were confirmed positive by either qRT-PCR and/or IgM ELISA. Out of the 21 characterized isolates, we identified 15 sequences belonging to the genotype 1e and 6 sequences to the genotype 2b. The newly characterized sequences from Niger clustered with those circulating in neighbouring countries, suggesting a cross-border virus circulation. The co-circulation of HEV genotypes 1 and 2 is an indicator of the probable virus transmission through contaminated water sources. Thus, there is a crucial need to improve the preparedness and implement an active and integrated community-based surveillance. This should include field testing for rapid detection and characterization of HEV as well as actions for disease containment, strengthening of hygiene measures and community-based sensitization for behavioural changes.

Global vaccination against hepatitis E virus: position paper from the European Society of Clinical Microbiology and Infectious Diseases Viral Hepatitis Study Group

SCOPE

Hepatitis E virus (HEV) is a significant global health issue, impacting both low- and middle-income countries and industrialized nations. HEV genotypes 1 and 2, primarily transmitted through contaminated water, are endemic in low- and middle-income countries, whereas genotypes 3 and 4 are zoonotically transmitted in industrialized regions. Acute HEV infection poses severe risks, particularly to pregnant women and immunocompromised individuals, whereas chronic HEV infection leads to serious complications in those with pre-existing liver disease and transplant recipients. The development of an HEV vaccine offers new prevention opportunities, though its availability and integration into global immunization programmes remain limited.

METHODS

This position paper was developed by the European Society of Clinical Microbiology and Infectious Diseases Viral Hepatitis Study Group through an extensive review of clinical data, safety profiles, efficacy, and immunogenicity of HEV vaccines. The study group focused particularly on high-risk and special populations, synthesizing global health insights and incorporating recommendations from the Strategic Advisory Group of Experts to formulate strategies for wider HEV vaccination use.

QUESTIONS ADDRESSED IN THE POSITION PAPER

The position paper evaluates the efficacy and safety of HEV vaccines in both general and special populations. It identifies key barriers to the integration of HEV vaccines into routine immunization programmes, including infrastructure limitations, costs, and vaccine accessibility. The paper also proposes strategies to overcome these challenges and improve vaccine distribution. Furthermore, it addresses ways to enhance public awareness and international cooperation to promote HEV vaccination efforts globally.

IMPLICATIONS

European Society of Clinical Microbiology and Infectious Diseases Viral Hepatitis Study Group recommends HEV vaccination for high-risk groups, including women of childbearing age, patients with chronic liver diseases, and immunosuppressed individuals. Prioritizing investments in vaccine logistics, integrating diagnostics, and educational outreach can enhance uptake.

Awareness, knowledge, disease prevention practices, and immunization attitude of hepatitis E virus among food handlers in Klang Valley, Malaysia

Concern about the zoonotic Hepatitis E virus (HEV) is rising. Since, food handlers are at greater risk in contracting HEV, the present study aims to determine awareness, knowledge, prevention practices against HEV, and immunization attitudes. A cross sectional study was conducted among 400 food handlers in Klang Valley, Malaysia from December 2021 to March 2022. A structured questionnaire was employed for data collection and analysis with Statistical Package for Social Science (SPSS) version 29. Approximately 4.5% of the respondents (18) reported having heard of HEV, while the median scores for the knowledge and practice domains were 0/10 and 1/5, respectively. A total of 316 (79%) respondents expressed willingness to obtain vaccination if made available. This study also found that those respondents who completed their tertiary education were significantly possessed better knowledge of the disease [odd ratio (OR) = 8.95, and 95% confidence interval (CI) 4.98-16.10]. Respondents with HEV awareness reported considerably better practices (OR = 8.24, 95% CI 1.72-39.63). Food handlers with one to five years of experience in the industry expressed notable willingness to take vaccination (OR = 7.71, 95% CI 1.79-33.18). Addressing poor HEV awareness and knowledge and poor practices against the disease is crucial in enlightening the policy makers about awareness among food handlers and general population. Nonetheless, a good immunization attitude, significant acceptance toward vaccination even with the vaccine being unavailable in Malaysia, and limited awareness of HEV highlight a promising development.

Raising the case of hepatitis E: Report from the 2nd international HEV symposium

The 2nd International Hepatitis E Virus Symposium was held on April 28 and 29, 2023, in London, UK. The conference was hosted by the International Vaccine Institute and brought together key clinicians, researchers, and private and public stakeholders for a dedicated forum on hepatitis E virus (HEV). The scientific program spanned multiple facets of HEV, from updates on clinical research and diagnostic advances to vaccine development. The conference highlighted presentations on several critical HEV vaccine studies that will greatly impact the field, including the largest effectiveness study of Hecolin vaccine outside of China and the first reactive mass-vaccination campaign in South Sudan. This report summarizes information shared at the convening and offers perspectives on the steps forward for hepatitis E.

Definitions, etiopathogenesis and epidemiology of ALF

Acute liver failure (ALF) is a rare but preventable cause of acute hepatic dysfunction which is associated with significant mortality, unless treated appropriately. There are significant regional variations in the etiologies of ALF globally and this determines the outcomes of the disease as well as the long-term survival in patients receiving liver transplantation for management. Improvements in understanding of disease pathophysiology and critical care medicine have led to better outcomes over the last few decades. Despite this, the burden of indeterminate ALF and the pathogenesis of many etiological agents are yet to be fully known. Improvements in diagnostic and prognostic modalities are expected to decrease the morbidity and mortality associated with ALF. Changes in vaccination programs and stronger legislative practices regarding over-the-counter sale of acetaminophen and non-proprietary drugs are expected to reduce the burden of disease globally.

Zoonotic and Food-Related Hazards Due to Hepatitis A and E in Africa: A Systematic Review and Meta-Analysis

Introduction

Foodborne infections are caused by a wide spectrum of microbial pathogens, and they pose a significant global health threat, resulting in millions of cases and thousands of fatalities annually. Among these pathogens, human viruses, including Hepatitis A virus (HAV) and Hepatitis E virus (HEV), play a significant role in foodborne viral outbreaks, especially in Africa. This systematic review determined the prevalence of these viruses in livestock and produce in Africa.

Method

A systematic search strategy was implemented following the PRISMA guidelines. Databases such as African Journal Online, Web of Science, Scopus, and PubMed were searched from their inception until November 30, 2023. Descriptive statistics and a proportional meta-analysis utilising a random-effects model with a 95% confidence interval were employed in the data analysis. The Cochrane risk-of-bias tool (ROB2) was utilised to evaluate the potential for bias in each study.

Results

The search identified 27 articles that met the inclusion criteria, among which seven focused on HAV, comprising a total of 309 samples, whereas 20 studies focused on HEV, comprising a total of 4238 samples. Egypt had the highest number of studies, followed by Cameroon and Nigeria. The meta-analysis revealed an overall prevalence of 33.8% (95% CI: 17.0-50.6) for HAV in ducks and shellfish and 22.0% (95% CI: 12.1-31.8) for HEV in various livestock. Genotype 3 was identified as the predominant genotype, for both HAV and HEV.

Conclusion

This review revealed a high prevalence of HAV and HEV in livestock populations in Africa, shedding light on the potential risks associated with zoonotic and/or food-related infections. There is a need for continued surveillance and monitoring of these viruses in both animals and food products to mitigate the risk of foodborne outbreaks and protect human health.

Prokaryote- and Eukaryote-Based Expression Systems: Advances in Post-Pandemic Viral Antigen Production for Vaccines

This review addresses the ongoing global challenge posed by emerging and evolving viral diseases, underscoring the need for innovative vaccine development strategies. It focuses on the modern approaches to creating vaccines based on recombinant proteins produced in different expression systems, including bacteria, yeast, plants, insects, and mammals. This review analyses the advantages, limitations, and applications of these expression systems for producing vaccine antigens, as well as strategies for designing safer, more effective, and potentially 'universal' antigens. The review discusses the development of vaccines for a range of viral diseases, excluding SARS-CoV-2, which has already been extensively studied. The authors present these findings with the aim of contributing to ongoing research and advancing the development of antiviral vaccines.

Hepatitis E virus: from innate sensing to adaptive immune responses

Hepatitis E virus (HEV) infections are a major cause of acute viral hepatitis in humans worldwide. In immunocompetent individuals, the majority of HEV infections remain asymptomatic and lead to spontaneous clearance of the virus, and only a minority of individuals with infection (5-16%) experience symptoms of acute viral hepatitis. However, HEV infections can cause up to 30% mortality in pregnant women, become chronic in immunocompromised patients and cause extrahepatic manifestations. A growing body of evidence suggests that the host immune response to infection with different HEV genotypes is a critical determinant of distinct HEV infection outcomes. In this Review, we summarize key components of the innate and adaptive immune responses to HEV, including the underlying immunological mechanisms of HEV associated with acute and chronic liver failure and interactions between T cell and B cell responses. In addition, we discuss the current status of vaccines against HEV and raise outstanding questions regarding the immune responses induced by HEV and treatment of the disease, highlighting areas for future investigation.

Rocahepevirus ratti: An underrecognised cause of acute hepatitis

Zoonoses are responsible for many of all emerging infectious diseases as well as for those already established. Rocahepevirus ratti is a rat-originated virus related to the hepatitis E virus (Paslahepevirus balayani) but highly divergent genetically from this, with a high cross-species infection potential and zoonotic transmission. It can infect humans, leading to acute hepatitis, and is primarily transmitted through the consumption of contaminated water. Rocahepevirus ratti was first discovered in Germany in 2010. The first human case was described in 2017 in Hong Kong in an immune-compromised patient. The first case of chronic infection with Rocahepevirus ratti was described in 2023. A meta-analysis based on 38 studies published between 2000 and 2023 identified 21 cases in humans described up to this date and 489 infections in different animals. Raising awareness regarding this virus is essential, as there are probably many cases that remain undiagnosed, and the virus even has the ability to produce chronic infections in selected patients.

Receipt of hepatitis E vaccine and fetal loss in rural Bangladesh: further analysis of a double-blind, cluster-randomised, controlled trial

BACKGROUND

Vaccination constitutes an attractive control measure for hepatitis E virus (HEV), a major cause of maternal and perinatal mortality globally. Analysis of pregnant participants in an effectiveness trial of the HEV vaccine HEV239 showed possible HEV239-associated fetal losses. We aimed to conduct a detailed analysis of this safety signal.

METHODS

In a double-blind, cluster-randomised trial, 67 villages in Matlab, Bangladesh, were randomly allocated (1:1) to two vaccine groups, in which non-pregnant women aged 16-39 years received either HEV239 (HEV239 group) or Hepa-B (a hepatitis B vaccine; control group). We implemented weekly surveillance for pregnancy detection, and follow-up of pregnancies once every 2 weeks, using physician-confirmed diagnoses to evaluate fetal loss outcomes (miscarriage [spontaneous abortion], stillbirth, and elective termination). Data from a parallel system of reproductive health surveillance in Matlab were used to clarify study diagnoses when necessary. Miscarriage was assessed only among participants whose first positive pregnancy test and vaccination date (for whichever dose was closest to the date of last menstrual period [LMP]) were before 20 weeks' gestation. We defined the following analysis periods of interest: from 90 days before the LMP until the pregnancy outcome (the proximal period); from the LMP date until the pregnancy outcome (the pregnancy period); from 90 days before the LMP until the LMP date (90 days pre-LMP period); and from enrolment until 90 days before the LMP (the distal period). Both Poisson and Cox regression models were used to assess the associations between receipt of HEV239 and fetal loss outcomes. The trial was registered with ClinicalTrials.gov (NCT02759991).

FINDINGS

Among the 19 460 non-pregnant participants enrolled in the trial, 5011 were identified as having pregnancies within 2 years following vaccination and met the criteria for analysis (2407 in the HEV239 group and 2604 in the control group). Among participants vaccinated in the proximal period and evaluated for miscarriage, miscarriage occurred in 54 (8·9%) of 607 in the HEV239 group and 32 (4·5%) of 719 in the control group (adjusted relative risk [aRR] 2·0 [95% CI 1·3-3·1], p=0·0009). Similarly, the risk of miscarriages was increased in the HEV239 group versus the control group among participants inadvertently vaccinated during pregnancy (22 [10·5%] miscarriages among 209 participants in the HEV239 group vs 14 [5·3%] of 266 in the control group; aRR 2·1 [95% CI 1·1-4·1], p=0·036) and among those vaccinated within 90 days pre-LMP (32 [8·0%] of 398 vs 18 [4·0%] of 453; 1·9 [1·1-3·2], p=0·013). No increased risk of miscarriage was observed in those who received HEV239 in the distal period (93 [5·6%] of 1647 vs 80 [4·5%] of 1773; 1·3 [0·8-1·9], p=0·295). Stillbirth and elective termination showed no increased risk among women administered HEV239 versus those administered Hepa-B in any of the analysis periods.

INTERPRETATION

HEV239 given shortly before or during pregnancy was associated with an elevated risk of miscarriage. This association poses a possible safety concern for programmatic use of HEV239 in women of childbearing age.

FUNDING

Research Council of Norway and Innovax.

Hepatitis E Vaccines Updates

The development of a hepatitis E vaccine is imperative given its prevalence and the heightened risk it poses to specific populations. Hepatitis E virus infection, though often self-limiting, poses a significant threat to pregnant individuals and immunocompromised populations. This review delves into the historical trajectory of hepatitis E vaccine development and explores its potential impact on at-risk populations. Historically, efforts to formulate an effective vaccine against hepatitis E have been underway to mitigate the severity of the disease, particularly in regions where the infection is commonplace. As a self-limiting disease, the necessity of a vaccine becomes more pronounced when considering vulnerable demographics. Pregnant individuals face heightened complications, with potential adverse outcomes for both mother and child. Similarly, immunocompromised individuals experience prolonged and severe manifestations of the infection, necessitating targeted preventive measures. This review aims to provide a comprehensive overview of the milestones in hepatitis E vaccine development. By examining the historical progression, we aim to underscore the critical need for a vaccine to safeguard not only the general population but also those at elevated risk. The elucidation of the vaccine's journey will contribute valuable insights into its potential benefits, aiding in the formulation of informed public health strategies to combat hepatitis E effectively.

Global burden of acute hepatitis E between 1990 and 2019 and projections until 2030

BACKGROUND AND AIMS

Acute hepatitis E (AHE) is still a public health issue worldwide. Here, we report the global burden of AHE in 204 countries and territories from 1990 to 2019 by age, sex and socio-demographic index (SDI), and predict the future trends to 2030.

METHODS

Data on AHE were collected from the Global Burden of Diseases, Injuries and Risk Factors Study 2019. The average annual percentage change (AAPC) and joinpoint analysis were used to determine the burden trend.

RESULTS

In 2019, there were 19.47 million (95% UI, 16.04 to 23.37 million) incident cases of AHE globally, with a 19% increase since 1990. Age-standardized rate (ASR) of disability-adjusted life years (DALYs), prevalent and incident cases declined from 1990 to 2019. In 2019, the ASR of incidence, prevalence and DALYs due to HEV infection were highest in the same regions of South Asia for both sexes. Southern Sub-Saharan Africa presented the highest increases in the ASR for incidence of HEV infection in both males (AAPC = .25) and females (AAPC = .24) from 1990 to 2019. Incident cases are higher in males than females before 55-59 years old. The SDI values were negatively correlated with the age-standardized DALYs. Between 2019 and 2030, the ASR for incidence and prevalence of HEV for both sexes showed an increasing trend.

CONCLUSIONS

Although the overall ASR of AHE decreased, the burden of AHE remains an underappreciated problem for society. The findings may provide useful information for policymakers to develop appropriate strategies aimed at reducing the burden of AHE.

Annual risk of hepatitis E virus infection and seroreversion: Insights from a serological cohort in Sitakunda, Bangladesh

Hepatitis E virus (HEV) is a major cause of acute jaundice in South Asia. Gaps in our understanding of transmission are driven by non-specific symptoms and scarcity of diagnostics, impeding rational control strategies. In this context, serological data can provide important proxy measures of infection. We enrolled a population-representative serological cohort of 2,337 individuals in Sitakunda, Bangladesh. We estimated the annual risks of HEV infection and seroreversion both using serostatus changes between paired serum samples collected 9 months apart, and by fitting catalytic models to the age-stratified cross-sectional seroprevalence. At baseline, 15% (95 CI: 14-17%) of people were seropositive, with seroprevalence highest in the relatively urban south. During the study, 27 individuals seroreverted (annual seroreversion risk: 15%, 95 CI: 10-21%), and 38 seroconverted (annual infection risk: 3%, 95CI: 2-5%). Relying on cross-sectional seroprevalence data alone, and ignoring seroreversion, underestimated the annual infection risk five-fold (0.6%, 95 CrI: 0.5-0.6%). When we accounted for the observed seroreversion in a reversible catalytic model, infection risk was more consistent with measured seroincidence. Our results quantify HEV infection risk in Sitakunda and highlight the importance of accounting for seroreversion when estimating infection incidence from cross-sectional seroprevalence data.

Evaluation and Immunogenicity of Combined Liposome-Based Vaccine Candidates against Hepatitis E and B Viruses in Rhesus Monkeys

The administration of vaccines using a combination approach ensures better coverage and reduces the number of injections and cost. The present study assessed liposome-complexed DNA-corresponding proteins of hepatitis E and B viruses (HEV and HBV) as combined vaccine candidates in rhesus monkeys. The HEV and HBV components consisted of 450 bps, neutralizing the epitope/s (NE) region, and 685 bps small (S) envelope gene-corresponding proteins, respectively. Three groups (n = 2 monkeys/group) were intramuscularly immunized with a total of three doses of NE Protein (Lipo-NE-P), NE DNA + Protein (Lipo-NE-DP), and each of NE and S DNA + Protein (Lipo-NES-DP), respectively, given one month apart. All immunized monkeys were challenged with 10,000 fifty percent monkey infectious dose of homologous HEV strain. Post-immunization anti-HEV antibody levels in monkeys were 59.4 and 148.4 IU/mL (Lipo-NE-P), 177.0 and 240.8 IU/mL (Lipo-NE-DP), and 240.7 and 164.9 IU/mL (Lipo-NES-DP). Anti-HBV antibody levels in Lipo-NES-DP immunized monkeys were 58,786 and 6213 mIU/mL. None of the challenged monkeys showed viremia and elevation in serum alanine amino transferase levels. Monkeys immunized with Lipo-NE-DP and Lipo-NES-DP exhibited a sterilizing immunity, indicating complete protection, whereas monkeys immunized with Lipo-NE-P showed limited viral replication. In conclusion, the liposome-complexed DNA-corresponding proteins of HEV and HBV induced protective humoral immune responses to both components in monkeys and are worth exploring further.

Virus-like particles as powerful vaccination strategy against human viruses

Nowadays, viruses are not only seen as causative agents of viral infectious diseases but also as valuable research materials for various biomedical purposes, including recombinant protein production. When expressed in living or cell-free expression systems, viral structural proteins self-assemble into virus-like particles (VLPs). Mimicking the native form and size of viruses and lacking the genetic material, VLPs are safe and highly immunogenic and thus can be exploited to develop antiviral vaccines. Some vaccines based on VLPs against various infectious pathogens have already been licenced for human use and are available in the commercial market, the latest of which is a VLP-based vaccine to protect against the novel Coronavirus. Despite the success and popularity of VLP subunit vaccines, many more VLPs are still in different stages of design, production, and approval. There are still many challenges that require to be addressed in the future before this surface display system can be widely used as an effective vaccine strategy in combating infectious diseases. In this review, we highlight the use of structural viral proteins to produce VLPs, emphasising their intrinsic properties, structural classification, and main expression host systems. We also compiled the recent scientific literature about VLP-based vaccines to underline the recent advances in their application as a vaccine strategy for preventing and fighting virulent human pathogens. Finally, we presented the key challenges and possible solutions for VLP-based vaccine production.

Seroprevalence of hepatitis E virus (HEV) among male craft and manual workers in Qatar (2020-2021)

Background

The rapid growth of Qatar in the last two decades has attracted a large influx of immigrant craft and manual workers (CMWs) seeking employment in jobs associated with food handling, domestic service, and construction. Nearly 60 % of Qatar's population are expatriates CMWs, including many from hyperendemic countries for HEV. Thus, estimating the seroprevalence of HEV in Qatar and understanding its epidemiology is essential for public health efforts to control HEV transmission in Qatar.

Methods

Blood samples from 2670 CMWs were collected between 2020 and 2021. All samples were tested for HEV-IgG antibodies. Positive HEV-IgG samples were tested for HEV-IgM antibodies, and those positives were also tested for viral antigens using an HEV-Ag ELISA kit and HEV-RNA by RT-PCR to confirm current HEV infections.

Results

The seroprevalence of HEV-IgG was 27.3 % (729/2670; 95 % CI: 25.6-29.0). Of those HEV-IgG positive, 8.23 % (60/729; 95 % CI: 6.30-10.5) were HEV-IgM positive. Of the IgM-positive samples, 2 were HEV-RNA positive (3.39 %; 95 % CI: 0.40-11.7), and 1 was HEV-Ag positive (1.69 %; 95 % CI: 0.04-9.09). In addition, HEV-IgG seroprevalence was associated with age and nationality, with the highest seroprevalence in participants from Egypt (IgG 60.0 %; IgM 5.56 %), Pakistan (IgG 59.0 %; IgM 2.24 %), Nepal (IgG 29.3 %; IgM 2.70 %), Bangladesh (IgG 27.8 %; IgM 2.45 %), and India (IgG 23.9 %; IgM 2.43 %).

Conclusion

In this study, we showed that the seroprevalence of HEV among CMWs was slightly higher than what was previously reported among the urban population in Qatar (2013-2016).

Hepatitis E Virus Infections: Epidemiology, Genetic Diversity, and Clinical Considerations

According to the World Health Organization, approximately 20 million people worldwide are infected annually with the hepatitis E virus (HEV). There are four main genotypes of HEV. Genotype 1 and genotype 2 are common in developing countries and are transmitted by contaminated water from a fecal-oral route. Genotype 3 and genotype 4 are common in developed countries and can lead to occasional transmission to humans via undercooked meat. Hepatitis E virus 1 and HEV3 can lead to fulminant hepatitis, and HEV3 can lead to chronic hepatitis and cirrhosis in immunocompromised patients. The majority of patients with HEV infection are asymptomatic and usually have spontaneous viral clearance without treatment. However, infection in immunocompromised individuals can lead to chronic HEV infection. Both acute and chronic HEV infections can have extrahepatic manifestations. No specific treatment is required for acute HEV infection, no treatment has been approved in chronic infection, and no HEV vaccine has been approved by the (United States) Food and Drug Administration. This review focuses on the molecular virology (HEV life cycle, genotypes, model systems, zoonosis), pathogenesis, clinical manifestation, and treatment of chronic HEV infection, especially in immunocompromised patients, to provide clinicians a better understanding of the global distribution of these infections and the significant effect they can have on immunocompromised patients.