Hepatitis E virus infection in a liver transplant recipient in the United States: a case report

The Re-Emergence of Hepatitis E Virus in Europe and Vaccine Development

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis. Transmission of HEV mainly occurs via the fecal-oral route (ingesting contaminated water or food) or by contact with infected animals and their raw meat products. Some animals, such as pigs, wild boars, sheep, goats, rabbits, camels, rats, etc., are natural reservoirs of HEV, which places people in close contact with them at increased risk of HEV disease. Although hepatitis E is a self-limiting infection, it could also lead to severe illness, particularly among pregnant women, or chronic infection in immunocompromised people. A growing number of studies point out that HEV can be classified as a re-emerging virus in developed countries. Preventative efforts are needed to reduce the incidence of acute and chronic hepatitis E in non-endemic and endemic countries. There is a recombinant HEV vaccine, but it is approved for use and commercially available only in China and Pakistan. However, further studies are needed to demonstrate the necessity of applying a preventive vaccine and to create conditions for reducing the spread of HEV. This review emphasizes the hepatitis E virus and its importance for public health in Europe, the methods of virus transmission and treatment, and summarizes the latest studies on HEV vaccine development.

Epidemiology and treatment of hepatitis E in the liver transplantation setting: A literature review

Hepatitis E virus (HEV) is a common cause of acute hepatitis in developing countries, but it can also take a chronic course especially in immunocompromised patients. Its epidemiology after liver transplantation (LT) is hard to assess and treatment options are still explored. Between 2009 and 2020, literature reporting HEV prevalence and treatment in LT recipients was searched and a synthesis was attempted. Sixteen studies reported HEV prevalence in consecutive LT patients: HEV RNA positivity ranged between 0%-1.4% and 0%-7.7% for Western and Eastern cohorts, respectively. In studies published between 2009-2014 and 2015-2020, HEV RNA positivity ranged between 0.35%-1.3% (all European) and 0%-7.7% (European: 0%-1.4%), respectively. Five studies evaluated HEV prevalence in LT recipients with abnormal liver enzymes: HEV RNA positivity was 2.9% in studies published between 2009 and 2014 and from 3.5% to 20% in studies published between 2015 and 2020. Twenty-seven studies reported HEV treatment in LT recipients: sustained virologic response was achieved in 15% by immunosuppression reduction alone and in 83% of cases by ribavirin regiments. Chronic HEV infection is affecting LT recipients, mostly those with abnormal liver enzymes and in Eastern countries. HEV diagnoses should be based on PCR techniques. Successful treatment can be achieved with ribavirin in most cases.

Seroprevalence of hepatitis E virus among blood donors on Corsica, France, 2017

Background

Hepatitis E virus (HEV) is an emerging zoonotic pathogen and an important cause of acute viral hepatitis in European countries. Corsica Island has been previously identified as a hyperendemic area for HEV.

Aim

Our aim was to characterise the prevalence and titres of IgG antibodies to HEV among blood donors on Corsica and establish a model of the annual force of infection.

Methods

Between September 2017 and January 2018, 2,705 blood donations were tested for anti-HEV IgG using the Wantai HEV IgG enzyme immunoassay.

Results

The overall seroprevalence was 56.1%. In multivariate analysis, seroprevalence was higher in men than in women (60.0% vs 52.2%; p < 0.01), increased with age and was significantly higher among donors born on Corsica (60.6% vs 53.2%; p < 0.01). No significant difference was observed between the five districts of the island. IgG anti-HEV titres were mostly low (70% of positive donors had titres < 3 IU/mL). In Corsican natives, increasing seroprevalence by age could be explained by models capturing a loss of immunity (annual probability of infection: 4.5%; duration of immunity: 55 years) or by age-specific probabilities of infection (3.8% for children, 1.3% for adults).

Conclusion

We confirmed the high HEV seroprevalence on Corsica and identified three aspects that should be further explored: (i) the epidemiology in those younger than 18 years, (ii) common sources of contamination, in particular drinking water, that may explain the wide exposure of the population, and (iii) the actual protection afforded by the low IgG titres observed and the potential susceptibility to secondary HEV infection.

Hepatitis E virus infection in liver transplant recipients: a descriptive literature review

Hepatitis E virus infection has been recognized as a rising hepatotropic viral infection in the developing countries but overlooked in the developed countries, due to its lower prevalence. However, hepatitis E virus prevalence is on rise in the liver transplant recipients due to immunosuppression, which needs prompt recognition by healthcare practitioners. Hepatitis E virus infection is commonly believed to be transmitted via an animal host; but in the post-liver transplant patients, it can also be acquired via blood and blood products transfusion and autochthonous route. Previous studies have shown the significance of hepatitis E virus infection in post-liver transplant, as the patients at a high risk of progressing to chronic hepatitis and cirrhosis. Pediatric patients are at higher risk of hepatitis E virus infection post-liver transplant. Specific hepatitis E virus genotypes have the potential for greater severity. The clinical manifestation of hepatitis E virus can also present as extrahepatic features which need high level of suspicion for early recognition and treatment. Treatment options of hepatitis E virus range from immunosuppressive drug minimization, ribavirin therapy to novel direct-acting antiviral regimens. Herein, we aim to explore epidemiology, prevalence, risk factor, diagnosis, and management of hepatitis E virus infection giving special attention to liver transplant recipients.

The expression patterns of immune response genes in the Peripheral Blood Mononuclear cells of pregnant women presenting with subclinical or clinical HEV infection are different and trimester-dependent: A whole transcriptome analysis

Hepatitis E is an enteric disease highly prevalent in the developing countries. The basis for high mortality among pregnant hepatitis E patients remains unclear. Importantly, a large proportion of infected pregnant women present with subclinical infection as well. In order to understand the possible mechanisms influencing clinical presentation of hepatitis E in pregnant women, we explored a system biology approach. For this, PBMCs from various categories were subjected to RNAseq analysis. These included non-pregnant (NPR, acute and convalescent phases) and pregnant (PR, 2^nd and 3^rd trimesters, acute phase and subclinical HEV infections) patients and corresponding healthy controls. The current study deals with immune response genes.

In contrast to exclusive up-regulation of nonspecific, early immune response transcripts in the NPR patients, the PR patients exhibited broader and heightened expression of genes associated with innate as well as adaptive T and B cell responses. The study identified for the first time (1) inverse relationship of immunoglobulin (Ig) genes overexpression and (2) association of differential expression of S100 series genes with disease presentation. The data suggests possible involvement of TLR4 and NOD1 in pregnant patients and alpha defensins in all patient categories suggesting a role in protection. Induction of IFNγ gene was not detected during the acute phase irrespective of pregnancy. Association of response to vitamin D, transcripts related to NK/NKT and regulatory T cells during subclinical infection are noteworthy.

The data obtained here could be correlated with several studies reported earlier in hepatitis E patients suggesting utility of PBMCs as an alternate specimen. The extensive, informative data provided here for the first time should form basis for future studies that will help in understanding pathogenesis of fulminant hepatitis E.

Donor-Derived Genotype 4 Hepatitis E Virus Infection, Hong Kong, China, 2018

Hepatitis E virus (HEV) genotype 4 (HEV-4) is an emerging cause of acute hepatitis in China. Less is known about the clinical characteristics and natural history of HEV-4 than HEV genotype 3 infections in immunocompromised patients. We report transmission of HEV-4 from a deceased organ donor to 5 transplant recipients. The donor had been viremic but HEV IgM and IgG seronegative, and liver function test results were within reference ranges. After a mean of 52 days after transplantation, hepatitis developed in all 5 recipients; in the liver graft recipient, disease was severe and with progressive portal hypertension. Despite reduced immunosuppression, all HEV-4 infections progressed to persistent hepatitis. Four patients received ribavirin and showed evidence of response after 2 months. This study highlights the role of organ donation in HEV transmission, provides additional data on the natural history of HEV-4 infection, and points out differences between genotype 3 and 4 infections in immunocompromised patients.

Screening of novel drugs for inhibiting hepatitis E virus replication

Hepatitis E, which is caused by hepatitis E virus (HEV), is generally a self-limiting, acute, and rarely fatal disease. It is sometimes fulminant and lethal, especially during pregnancy. Indeed, it occasionally takes a chronic course in immunocompromised individuals. To cure hepatitis E patients, the broad-spectrum antivirals (ribavirin and pegylated interferon α) are used. However, this treatment is insufficient and unsafe in some patients due to embryoteratogenic effects, leukopenia, and thrombocytopenia. In this study, we constructed an HEV replication reporter system with Gaussia luciferase for comprehensively screening anti-HEV drug candidates, and developed a cell-culture system using cells robustly producing HEV to validate the efficacy of anti-HEV drug candidates. We screened anti-HEV drug candidates from United States Food and Drug Administration-approved drugs using the established HEV replication reporter system, and investigated the selected candidates and type III interferons (interferon λ1-3) using the cell-culture system. In conclusion, we constructed an HEV replicon system for anti-HEV drug screening and a novel cell-culture system to strictly evaluate the replication-inhibitory activities of the obtained anti-HEV candidates. Our findings suggested that interferon λ1-3 might be effective for treating hepatitis E.

Epidemiology and Transmission of Hepatitis A Virus and Hepatitis E Virus Infections in the United States

There are many similarities in the epidemiology and transmission of hepatitis A virus (HAV) and hepatitis E virus (HEV) genotype (gt)3 infections in the United States. Both viruses are enterically transmitted, although specific routes of transmission are more clearly established for HAV than for HEV: HAV is restricted to humans and primarily spread through the fecal-oral route, while HEV is zoonotic with poorly understood modes of transmission in the United States. New cases of HAV infection have decreased dramatically in the United States since infant vaccination was recommended in 1996. In recent years, however, outbreaks have occurred among an increasingly susceptible adult population. Although HEV is the most common cause of acute viral hepatitis in developing countries, it is rarely diagnosed in the United States.

Meta-Analysis of Human IgG anti-HEV Seroprevalence in Industrialized Countries and a Review of Literature

Although Hepatitis E is increasingly described as a major cause of liver disease in industrialized countries, the epidemiology is far from being fully elucidated. We provide here a comprehensive review of documented clusters of cases, and of serological studies conducted in populations with distinct types of exposure. Seroprevalence rates range from <5% to >50% depending on the countries and the groups of population. Such discrepancies can be attributed to the type of serological assay used, but this solves only a part of the problem. We performed a meta-analysis of studies performed with the broadly used Wantai HEV-IgG ELISA and found striking differences that remain difficult to understand with the current knowledge of transmission pathways.

Hepatitis E in High-Income Countries: What Do We Know? And What Are the Knowledge Gaps?

Hepatitis E virus (HEV) is a positive-strand RNA virus transmitted by the fecal–oral route. HEV genotypes 1 and 2 infect only humans and cause mainly waterborne outbreaks. HEV genotypes 3 and 4 are widely represented in the animal kingdom, and are mainly transmitted as a zoonosis. For the past 20 years, HEV infection has been considered an imported disease in developed countries, but now there is evidence that HEV is an underrecognized pathogen in high-income countries, and that the incidence of confirmed cases has been steadily increasing over the last decade. In this review, we describe current knowledge about the molecular biology of HEV, its clinical features, its main routes of transmission, and possible therapeutic strategies in developed countries.

Hepatitis E: Still Waters Run Deep

Hepatitis E is an infectious inflammatory disease of the liver caused by the hepatitis E virus (HEV), a single-stranded RNA virus. Today, it is estimated that there are more than 20 million HEV infections every year, leading to 3.3 million symptomatic cases and more than 56,000 deaths. For a long time it was believed that HEV was a travel-associated disease, endemic in developing countries with poor hygienic standards and unsafe water supply. However, over the past years, publications have demonstrated that autochthonous HEV infections in industrialized countries are far more common than previously thought. Awareness for HEV amongst health care practitioners in industrialized countries is still limited. This relatively rare disease is of great importance, especially in immunocompromised patients where it can cause chronic liver disease. This article comprehensively reviews current literature to give an overview on clinically important topics. It will focus on epidemiological aspects, acute and chronic HEV infection as well as extra-hepatic manifestations, diagnostic approach and treatment options. Furthermore, the article is concluded with a brief outlook on perspectives and urgent problems to be addressed in the future.

HHV-6 in liver transplantation: A literature review

Human herpesvirus 6 (HHV-6A and HHV-6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV-6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV-6 remains the gold standard for diagnosis of end-organ disease. HHV-6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV-6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue-invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV-6 (ciHHV-6), in either the recipient or the donor organ, may create confusion about systemic HHV-6 infection. Recipients with inherited ciHHV-6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV-6 infections in liver transplant recipients.

Hepatitis E virus: An ancient hidden enemy in Latin America

Hepatitis E virus (HEV) infection is a common cause of acute clinical hepatitis worldwide. HEV is an RNA-containing virus and the only member of the genus Hepevirus in the family Hepeviridae. Human HEV is classified into four genotypes widely distributed across the world. The virus is mainly transmitted via the fecal-oral route, and water-borne epidemics have become characteristic of hepatitis E in developing countries, including those in Latin America. The zoonotic potential of HEV is broadly recognized. Thus, there is an urgent need to re-evaluate virus transmission scenarios and to enforce epidemiological surveillance systems. Additionally, it is known that HEV infections, initially defined as self-limiting, can also take chronic courses in immunocompromised patients. Moreover, we recently reported a high seroprevalence of HEV in samples from cirrhotic patients with no other etiological agents present, suggesting the potential role of HEV in the development of chronic liver illness. In this review, HEV genomic variability, transmission, chronic infectious course, zoonotic potential and treatment are discussed. Focus is placed on the impact of HEV infection in Latin America, to support the development of specific control strategies and the handling of this important and typically imperceptible viral infection.

Full coding hepatitis E virus genotype 3 genome amplification method

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A new amplification method for the complete HEV coding genome was described.

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HEV genome organization and function were reviewed.

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Polymorphic amino acids of each HEV genome region were analyzed in reference sequences.

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Complete coding HEV sequence of an immunocompromised patient with acute infection was analyzed.

Hepatitis E virus (HEV) genotype 3 produces zoonotic infection associated with the consumption of infected animals. HEV infections can become chronic in immunocompromised (IC) patients. The viral genome has three well defined open reading frames (ORF1, ORF2 and ORF3) within which various domains and functions have been described. This paper (i) describes a new method of complete sequencing of the HEV coding region through overlapping PCR systems, (ii) establishes a consensus sequence and polymorphic positions (PP) for each domain, and (iii) analyzes the complete coding sequence of an IC patient. With regard to the consensus, a high percentage of PP was observed in protease (PP = 19%) and the X domain (PP = 22%) within ORF1, the N-terminal region of the S domain (PP = 22%) in ORF2, and the P1 (PP = 35%) and P2 (PP = 25%) domains in ORF3. In contrast, the ORF1 Y, ORF2 S, ORF2 M and ORF3 D1 domains were conserved in the reference sequences (0.40, 1, 0.70 and 0% of PP, respectively). The sequence from the IC patient had more mutations in the RpRp (D1235G, Q1242R, S1454T, V1480I, I1502 V, K1511R, G1373 V, E1442D, V1693 M), the terminal ORF2 S- domain (F10L, S26T, G36S, S70P, A105 V, I113 V), the X domain (T938 M, T856 V, S898A) and the helicase (S1014N, S975T, Q1133 K).

Hepatitis E Virus Infection Among Solid Organ Transplant Recipients at a North American Transplant Center

Background.  Autochthonous hepatitis E virus (HEV) infection has been reported in over 200 solid organ transplant (SOT) recipients since 2006, yet little is known about the burden of HEV among SOT recipients in North America. We performed a retrospective, cross-sectional study to investigate the prevalence and risk factors associated with HEV infection among SOT recipients at our institution. Methods.  Children and adults (n = 311) who received allografts between 1988 and 2012 at the Johns Hopkins Hospital were assessed for evidence of HEV infection by testing posttransplantation serum samples for HEV antibody by enzyme immunoassay and HEV RNA by reverse transcription quantitative polymerase chain reaction. Individuals with evidence of posttransplant HEV infection (presence of anti-HEV immunoglobulin [Ig]M antibody, anti-HEV IgG seroconversion, or HEV RNA) were compared with individuals without evidence of infection and assessed for risk factors associated with infection. Results.  Twelve individuals (4%) developed posttransplant HEV infection. Posttransplant HEV infection was associated with an increased risk for graft rejection (odds ratio, 14.2; P = .03). No individuals developed chronic infection. Conclusions.  Solid organ transplant recipients in the United States are at risk for posttransplant HEV infection. Further studies are needed to characterize environmental risk factors and the risk of HEV infection after SOT in North America.

Is hepatitis E virus an emerging problem in industrialized countries?

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.

Epidemiology of Hepatitis E Virus in European Countries

Over the last decade the seroprevalence of immunoglobulin (IgG) anti hepatitis E virus (HEV) has been increasing in European countries and shows significant variability among different geographical areas. In this review, we describe the serological data concerning the general population and risk groups in different European countries. Anti-HEV antibody prevalence ranged from 1.3% (blood donors in Italy) to 52% (blood donors in France). Various studies performed on risk groups in Denmark, Moldova and Sweden revealed that swine farmers have a high seroprevalence of HEV IgG (range 13%-51.1%), confirming that pigs represent an important risk factor in HEV infection in humans. Subtypes 3e,f are the main genotypes detected in the European population. Sporadic cases of autochthonous genotype 4 have been described in Spain, France, and Italy. Although most HEV infections are subclinical, in immune-suppressed and transplant patients they could provoke chronic infection. Fulminant hepatitis has rarely been observed and it was related to genotype 3. Interferon and ribavirin treatment was seen to represent the most promising therapy.

Hepatitis E virus in the countries of the Middle East and North Africa region: an awareness of an infectious threat to blood safety

PURPOSE

Hepatitis E virus (HEV) is mainly transmitted through contaminated water supplies which make the virus endemic in developing countries including countries of the Middle East and North Africa (MENA) region. Recent reports suggest potential risk of HEV transmission via blood transfusion.

METHODS

Related articles on HEV were collected by searching through the 25 countries of the MENA region using Pubmed and Medline within the past 14 years: January 2000-August 2014.

RESULTS

One hundred articles were extracted, of which 25 were not eligible. The articles discussed the seroprevalence of HEV and HEV markers in 12 countries. Eight articles provided data on HEV in blood donors. The seroprevalence of HEV in the general MENA population ranged from 2.0 to 37.5% and was higher in males than in females. Prevalence increased with age, but exposure seems to be in early life.

CONCLUSIONS

In the MENA region, the role of HEV as an infectious threat to blood safety is under-investigated. More data are needed to quantify the risk of transmission and to assess clinical outcomes. This requires, at least, surveillance screening of donors and recipients for HEV markers using sensitive and specific serological tests. At the present time, serious consideration should be given to selective screening for certain groups of patients (e.g., immunocompromised, pregnant women and others) who commonly require blood transfusion and are at high risk of hepatic failure or chronicity from HEV infection.

Variability of hepatitis E serologic assays in a pediatric liver transplant recipient: challenges to diagnosing hepatitis E virus infection in the United States

Hepatitis E virus (HEV) is an emerging cause of viral hepatitis among immunocompromised individuals in developed countries. Yet the diagnosis of HEV infection in the United States remains challenging, because of the variable sensitivity and specificity of currently available tests, and the lack of a US Food and Drug Administration-approved test. We report a case of multiple discordant HEV serology results in a pediatric liver transplant recipient with idiopathic hepatitis, and review the challenges to diagnosis of HEV infection in the United States.

Infections after orthotopic liver transplantation

Opportunistic infections are a leading cause of morbidity and mortality after orthotopic liver transplantation. Systemic immunosuppression renders the liver recipient susceptible to de novo infection with bacteria, viruses and fungi post-transplantation as well to reactivation of pre-existing, latent disease. Pathogens are also transmissible via the donor organ. The time from transplantation and degree of immunosuppression may guide the differential diagnosis of potential infectious agents. However, typical systemic signs and symptoms of infection are often absent or blunted after transplant and a high index of suspicion is needed. Invasive procedures are often required to procure tissue for culture and guide antimicrobial therapy. Antimicrobial prophylaxis reduces the incidence of opportunistic infections and is routinely employed in the care of patients after liver transplant. In this review, we survey common bacterial, fungal, and viral infections after orthotopic liver transplantation and highlight recent developments in their diagnosis and management.

Changes in the cellular proteins of A549 infected with hepatitis E virus by proteomics analysis

Background

Our understanding of Hepatitis E virus (HEV) has changed enormously over the past 30 years, from a waterborne infection causing outbreaks of acute hepatitis in developing countries to an infection of global distribution causing a range of hepatic and extra-hepatic illness. However, the key proteins playing important parts in the virus infection were still unknown. Understanding the changes of cellular proteins in these cells exposed to HEV is helpful for elucidating molecular mechanisms associated with function alterations of HEV-infected susceptible cells. In the present study, a comparative gel-based proteomic analysis was employed to study the changes in cellular proteins of A549 exposed to HEV in vitro to provide novel information for understanding the functional alterations of A549 induced by HEV infection.

Result

Of 2 585-3 152 protein spots visualized on each gel using silver staining, a total of 31 protein spots were found to be differentially expressed in HEV-infected A549 cells compared with mock-infected A549, including 10 significantly up-regulated protein spots and 21 significantly down-regulated protein spots.

Conclusion

Our work is the first time regarding the proteomic analysis on the cellular responses to HEV infection. This work is helpful for investigating the molecular basis associated with the interaction between HEV and the host cells although more efforts should be required to discover the mechanisms.

Decline in hepatitis E virus antibody prevalence in the United States from 1988-1994 to 2009-2010

BACKGROUND

Previous population-based estimates in the United States have shown a relatively high prevalence of hepatitis E virus (HEV) antibody. We sought to determine whether changes in the prevalence of HEV antibody have occurred over time.

METHODS

We analyzed data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) and NHANES III (1988-1994). Using the same serologic assay, we compared the estimated anti-HEV immunoglobulin G (IgG) prevalence and risk factors for antibody positivity for the 2 periods.

RESULTS

The prevalence of HEV antibody among those aged ≥6 years declined from 10.2% (95% confidence interval [CI], 9.1%-11.4%) during 1988-1994 to 6.0% (5.2%-6.8%) during 2009-2010, and the prevalence for those of US birth ranged from 9.6% (8.4%-10.9%) to 5.2% (4.4%-6.2%). Among US-born persons, the estimated HEV antibody prevalence declined significantly for all subgroups of age, sex, region of residence, and number of persons per room in the household; significant declines also were observed for persons at or above poverty level and for persons of non-Hispanic white, non-Hispanic black, and Mexican American race/ethnicity. No clear associations with food consumption were found.

CONCLUSIONS

The anti-HEV prevalence is declining in the United States. Although the decline suggests a decrease in exposure to HEV over time, the risks associated with exposure remain unknown.

Hepatitis E virus infection

Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. Hepatitis E is an underdiagnosed disease, in part due to the use of serological assays with low sensitivity. However, diagnostic tools, including nucleic acid-based tests, have been improved. The epidemiology and clinical features of hepatitis E differ between developing and developed countries. HEV infection is usually an acute self-limiting disease, but in developed countries it causes chronic infection with rapidly progressive cirrhosis in organ transplant recipients, patients with hematological malignancy requiring chemotherapy, and individuals with HIV. HEV also causes extrahepatic manifestations, including a number of neurological syndromes and renal injury. Acute infection usually requires no treatment, but chronic infection should be treated by reducing immunosuppression in transplant patients and/or the use of antiviral therapy. In this comprehensive review, we summarize the current knowledge about the virus itself, as well as the epidemiology, diagnostics, natural history, and management of HEV infection in developing and developed countries.

Hepatitis E infection in liver transplant recipients

Hepatitis E virus (HEV) infection (genotype 3) has been described in developed countries as a cause of chronic hepatitis in recipients of solid organ transplantation (SOT), with the first cases reported in 2008. Immunosuppression seems to play a major role in the pathogenesis of chronic infections. The current gold standard for the diagnosis of HEV infection is the detection of HEV RNA in serum, stools, or both. In liver transplant recipients, HEV infection is considered an uncommon disease; however, a high index of suspicion is needed for patients with graft hepatitis of an unclear etiology. Liver transplant recipients seem more likely to develop chronic HEV after an acute infection, and there is accelerated progression to advanced fibrosis and cirrhosis. A decrease in immunosuppression is considered the first line of treatment, and pegylated interferon can be considered the second line of treatment for liver transplant recipients. At the present time, there are not enough data to recommend treatment with ribavirin for adult liver transplant recipients, although this has been tried in other SOT populations.

Hepatitis E: when to treat and how to treat

HEV generally causes a self-limited acute infection and treatment remains supportive. However, severe hepatitis or fulminant hepatic failure may occur, more so during pregnancy. It is an important cause of acute-on-chronic liver failure in endemic areas. Chronic HEV infection and progressive disease has been reported in recipients of solid organ transplants, haematological malignancies, HIV patients and those on haemodialysis. Clearance of HEV may occur after reducing immunosuppressive therapy, especially those targeting T-cells, in about one third of cases. Antiviral therapy should be considered for patients for whom immunosuppressive therapy cannot be reduced and for those who do not achieve viral clearance after reducing immunosuppression. For the patients with severe infection, fulminant hepatic failure and acute-on-chronic infection, ribavirin monotherapy should be considered to expedite the viral clearance and recovery. Although ribavirin therapy is contraindicated in pregnancy owing to teratogenicity, the risks of untreated HEV to the mother and fetus are high and treatment may be offered. A twelve-week course of pegylated interferon, ribavirin or a combination of the two agents leads to viral clearance in about two-thirds of patients with chronic hepatitis E. Three- to twelve-month treatment with pegylated interferon clears virus in liver transplant recipients and patients on haemodialysis. In kidney and heart transplant patients where interferon may lead to organ rejection, ribavirin may be given.

Chronic hepatitis e virus infection and treatment

It is now well accepted that hepatitis E virus (HEV) infection can induce chronic hepatitis and cirrhosis in immunosuppressed patients. Chronic genotype-3 HEV infections were first reported in patients with a solid-organ transplant. Thereafter, cases of chronic HEV infection have been reported in patients with hematological disease and in those who are human immunodeficiency virus (HIV)-positive. HEV-associated extra-hepatic manifestations, including neurological symptoms, kidney injuries, and hematological disorders, have been also reported. In transplant patients, reducing the dosage of immunosuppressive drugs allows the virus to be cleared in some patients. In the remaining patients, as well as hematological patients and patients who are HIV-positive, anti-viral therapies, such as pegylated interferon and ribavirin, have been found to be efficient in eradicating HEV infection. This review summarizes our current knowledge of chronic HEV infection, its treatment, and the extra-hepatic manifestations induced by HEV.