Recent advances in hepatitis E virus research and the Japanese clinical practice guidelines for hepatitis E virus infection

Acute hepatitis E was considered rare until reports emerged affirming the existence of hepatitis E virus (HEV) genotypes 3 and 4 infections in Japan in the early 2000s. Extensive studies by Japanese researchers have highlighted the pivotal role of pigs and wild animals, such as wild boars and deer, as reservoirs for HEV, linking them to zoonotic infections in Japan. Currently, when hepatitis occurs subsequent to the consumption of undercooked or grilled pork, wild boar meat, or offal (including pig liver and intestines), HEV infection should be considered. Following the approval of anti-HEV immunoglobulin A antibody as a diagnostic tool for hepatitis E by Japan's Health Insurance System in 2011, the annual number of diagnosed cases of HEV infection has surged. Notably, the occurrence of post-transfusion hepatitis E promoted nationwide screening of blood products for HEV using nucleic acid amplification tests since 2020. Furthermore, chronic hepatitis E has been observed in immunosuppressed individuals. Considering the significance of hepatitis E, heightened preventive measures are essential. The Japan Agency for Medical Research and Development Hepatitis A and E viruses (HAV and HEV) Study Group, which includes special virologists and hepatologists, held a virtual meeting on February 17, 2024. Discussions encompassed pathogenesis, transmission routes, diagnosis, complications, severity factors, and ongoing and prospective vaccination or treatments for hepatitis E. Rigorous assessment of referenced studies culminated in the formulation of recommendations, which are detailed within this review. This comprehensive review presents recent advancements in HEV research and Japanese clinical practice guidelines for HEV infection.

A Case of Hepatitis E Virus Infection: One of Differential Diagnosis of Liver Injury in Patients Undergoing Peritoneal Dialysis

Background

There are numerous causes of liver function disorder in patients undergoing peritoneal dialysis (PD). Infection with the Hepatitis E virus (HEV) is a rare cause of liver injury, and the behavior of HEV in patients with PD is unclear. Since patients undergoing dialysis are frequently polypharmatic, liver injury caused by HEV infection may be misdiagnosed as drug-induced liver injury.

Case Presentation

A 61-year-old woman with PD developed abrupt elevation of blood transaminase levels on a routine outpatient session. Since the patient has been receiving tolvaptan as the only new medication, we suspected tolvaptan induced liver injury. In further investigating the cause of liver injury, the blood screening test was found to be positive for HEV-IgA. The patient was diagnosed with HEV infection, and had a self-limited course.

Conclusion

When encountered with patients developing liver injury during PD, HEV infection should be included in the differential diagnosis.

Fatal Fulminant Hepatitis E in a Diabetic Patient on Metformin

Hepatitis E is mostly autochthonous in Western developed countries, eating pig-derived products being the most frequently documented source. Hepatitis E virus (HEV) infection is usually asymptomatic or self-limiting, but it can cause acute liver failure. HEV serological testing was performed using EUROIMMUN immunoenzymatic assays. HEV RNA in the serum was determined using an in-house real-time reverse transcriptase PCR procedure. The HEV genotype was determined through phylogenetic analysis after Sanger sequencing was performed using an in-house procedure. The case patient, an immunocompetent patient in his 60s with type 2 diabetes and no documented chronic liver disease, was hospitalized in February 2021 in an intensive care unit due to an initially unexplained coma. He presented metformin overdose and fulminant hepatitis E (HEV RNA in the serum was 4,140,000 copies/mL) that evolved toward death. The HEV genotype was 3f. We identified eight previous hepatitis E in diabetic patients, but with no metformin excessive plasma concentration, in the literature. Three patients were liver transplant recipients and three died. HEV infection can be severe and life-threatening in diabetic patients, which warrants HEV testing in this special population in the case of an altered general condition and/or liver cytolysis.

Loss of antibodies to hepatitis E virus in organ transplant patients with hepatitis E

AIM

Studies regarding changes in antibodies to hepatitis E virus (HEV) after HEV infection in organ transplant patients are limited. This study aimed to clarify HEV infection trends in organ transplant patients who contracted HEV using data from a previous Japanese nationwide survey.

METHODS

This study was undertaken from 2012 to 2019. Among 4518 liver, heart, and kidney transplant patients, anti-HEV immunoglobulin G (IgG) antibodies were positive in 164; data were collected from 106 of these patients, who consented to participate in the study. In total, 32 liver transplant patients, seven heart transplant patients, and 67 kidney transplant patients from 16 institutions in Japan were examined for IgG, IgM, and IgM antibodies to HEV and the presence of HEV RNA in the serum. The χ² -test was used to determine the relationship between the early and late postinfection groups in patients with anti-HEV IgG positive-to-negative conversion rates. The Mann-Whitney U-test was used to compare clinical factors.

RESULTS

Anti-HEV IgG positive-to-negative conversion occurred in 25 (23.6%) of 106 organ transplant patients. Of eight patients with hepatitis E who tested positive for HEV RNA, one (14.0%) had anti-HEV IgG positive-to-negative conversion. Twenty-four (24.5%) of 98 patients negative for HEV RNA had anti-HEV IgG positive-to-negative conversion.

CONCLUSIONS

This study revealed, for the first time, the changes in HEV antibodies in organ transplant patients. Loss of anti-HEV IgG could often occur unexpectedly in organ transplant patients with previous HEV infection.

Identification of Emerging Hazards in Mussels by the Galician Emerging Food Safety Risks Network (RISEGAL). A First Approach

Emerging risk identification is a priority for the European Food Safety Authority (EFSA). The goal of the Galician Emerging Food Safety Risks Network (RISEGAL) is the identification of emerging risks in foods produced and commercialized in Galicia (northwest Spain) in order to propose prevention plans and mitigation strategies. In this work, RISEGAL applied a systematic approach for the identification of emerging food safety risks potentially affecting bivalve shellfish. First, a comprehensive review of scientific databases was carried out to identify hazards most quoted as emerging in bivalves in the period 2016-2018. Then, identified hazards were semiquantitatively assessed by a panel of food safety experts, who scored them accordingly with the five evaluation criteria proposed by EFSA: novelty, soundness, imminence, scale, and severity. Scores determined that perfluorinated compounds, antimicrobial resistance, Vibrio parahaemolyticus, hepatitis E virus (HEV), and antimicrobial residues are the emerging hazards that are considered most imminent and severe and that could cause safety problems of the highest scale in the bivalve value chain by the majority of the experts consulted (75%). Finally, in a preliminary way, an exploratory study carried out in the Galician Rías highlighted the presence of HEV in mussels cultivated in class B production areas.

Detection of Hepatitis E Virus in Shellfish Harvesting Areas from Galicia (Northwestern Spain)

The hepatitis E virus (HEV) affects almost 20 million individuals annually, causing approximately 3.3 million acute liver injuries, 56,600 deaths, and huge healthcare-associated economic losses. Shellfish produced close to urban and livestock areas can bioaccumulate this virus and transmit it to the human population. The aim of this study was to evaluate the presence of HEV in molluscan shellfish, in order to deepen the knowledge about HEV prevalence in Galicia (northwestern Spain), and to investigate this as a possible route of HEV transmission to humans. A total of 168 shellfish samples was obtained from two different Galician rías (Ría de Ares-Betanzos and Ría de Vigo). The samples were analyzed by reverse transcription-quantitative PCR (RT-qPCR). RT-nested PCR and sequencing were used for further genotyping and phylogenetic analysis of positive samples. HEV was detected in 41 (24.4%) samples, at quantification levels ranging from non-quantifiable (<102 copies of the RNA genome (RNAc)/g tissue) to 1.1 × 105 RNAc/g tissue. Phylogenetic analysis based on the open reading frame (ORF)2 region showed that all sequenced isolates belonged to genotype 3, and were closely related to strains of sub-genotype e, which is of swine origin. The obtained results demonstrate a significant prevalence of HEV in bivalve molluscs from Galician rías, reinforcing the hypothesis that shellfish may be a potential route for HEV transmission to humans.

High seroprevalence of anti-Hepatitis E antibodies in Austrian patients with autoimmune hepatitis

BACKGROUND & AIMS

Increasing numbers of autochthonous hepatitis E virus infections have been reported in Europe. Chronic infections have been shown in immune-compromised patients after solid organ transplantation. Hepatitis E virus might be a possible trigger for autoimmune hepatitis and might cause disease flares or relapses in the further course of disease. Aim of this study was to investigate the presence of hepatitis E virus antibodies and hepatitis E virus RNA, and to analyse their impact on immunosuppressive treatment in patients with autoimmune hepatitis.

METHODS

Sera from 92 autoimmune hepatitis patients (73/79.3% female, age: 42.2 ± 16.3 years [mean ± SD]) were tested. Patients were scored according to the simplified and revised scoring systems of the International Autoimmune Hepatitis Group. The prevalence of anti- hepatitis E virus antibodies (Beijing Wantai Biological Pharmacy Enterprises Co., Ltd, Beijing, China) and hepatitis E virus RNA was determined.

RESULTS

19/20.7% autoimmune hepatitis patients tested positive for hepatitis E virus-IgG, which was higher than in previous reports of healthy Austrian individuals (12.4%, P = 0.031); hepatitis E virus RNA was not detectable in any patient. Anti-hepatitis E virus positive patients were older (49.5 ± 9.5 vs 40.4 ± 17.2 years [mean ± SD], P = 0.033) but did not differ in laboratory findings at diagnosis (AST: 14.6 [1.3-70.6] vs 9.5 [0.7-62.7] × ULN [median/range]; P = 0.387, alanine aminotransferase: 18.3 [1.6-62.7] vs. 12.9 [0.8-62.6] × ULN; P = 0.511; IgG: 1.4 [1.0-2.5] vs 1.3 [0.6-3.8] g/dL × ULN; P = 0.278) nor in alanine aminotransferase levels after six months (0.7 [0.5-2.4] vs 1.0 U/L × ULN [0.1-22.4]; P = 0.077).

CONCLUSIONS

No chronic hepatitis E virus infection was observed in our cohort of autoimmune hepatitis patients. Anti- hepatitis E virus-IgG positive patients were older and the seroprevalence was nearly twice as high as reported previously in healthy Austrian individuals, suggesting that hepatitis E virus-infection might act as trigger for the development of autoimmune hepatitis.

High prevalence of hepatitis E virus infection among domestic pigs in Ibaraki Prefecture, Japan

BACKGROUND

Hepatitis E virus (HEV) is prevalent in pigs and may serve as a reservoir for human infection. However, data on HEV infections in pigs in Ibaraki Prefecture, Japan, are limited. Here, we clarified the process and course of HEV in naturally infected pigs. Serum (n = 160) and liver (n = 110) samples were collected from pigs at the slaughterhouse. Furthermore, serum samples were collected from 45 breeding sows and serum and feces samples were collected from 7 piglets once a week (raised until 166 days of age). HEV antigen and antibodies were evaluated, and the genotype was identified based on molecular phylogenetic tree analysis.

RESULTS

The samples collected from the slaughterhouse revealed that few pigs were HEV carriers but most possessed anti-HEV antibodies. Most breeding sows possessed antibodies, and the piglets excreted HEV on the farm at approximately 10 weeks of age. One pig was initially infected, and in a few weeks, the other pigs living in the same sty became infected.

CONCLUSIONS

Most pigs in Ibaraki Prefecture were with HEV. On the farm, most piglets were infected with HEV by the time they reached slaughter age. We confirmed that HEV infection is successively transmitted among piglets living in the same sty.

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.

Autoimmune liver disease serology in acute hepatitis E virus infection

The etiology of autoimmune hepatitis (AIH) is unknown, though hepatotropic viruses may be potential triggers. Hepatitis E virus (HEV) infection, an increasingly recognized cause of acute hepatitis, has been misdiagnosed as AIH due to the occurrence of autoantibodies during its acute phase. It has also been suggested that HEV infection may lead to or unmask AIH. The HEV seroprevalence has been ascertained in patients with AIH, but the prevalence of AIH-related autoantibodies in patients with HEV infection has not been systematically tested. We aimed to investigate whether acute HEV infection is associated with the presence of AIH-relevant autoantibodies, following the liver autoimmune serology guidelines of the International AIH Group. We tested 48 patients with acute HEV infection. Half of them had at least one autoantibody, 17% two autoantibodies. Anti-nuclear antibody (ANA) were detected in 16 (33%), anti-smooth muscle antibody (SMA) in 10 (21%), and anti-neutrophil cytoplasmic antibody (ANCA) in 7 (14.6%). Of note, two patients showed SMA with VG or VGT patterns and five had ANA with homogeneous appearance, both being typical of AIH type 1. Other AIH-specific autoantibodies were negative. Atypical anti-mitochondrial antibody, without evidence of primary biliary cholangitis, was positive in one patient, disappearing at follow-up. Follow-up (median 12 months) serum was available from seven autoantibody positive patients: two became negative, while five remained positive, although no patient developed AIH to date. In conclusion, autoantibodies are frequently present during acute HEV infection, indicating that HEV should always be excluded before diagnosing AIH. Importantly, a minority of patients with acute hepatitis E develops AIH-specific autoantibodies, and, though they did not progress to autoimmune liver disease in the short-term, they warrant long-term monitoring.

An Update on the Clinicopathologic Features and Pathologic Diagnosis of Hepatitis E in Liver Specimens

Infection with the hepatitis E virus (HEV) is globally seen a leading cause of hepatitis. Now increasingly recognized also in industrialized countries, hepatitis E constitutes a significant health problem worldwide. The patient's immune status determines the clinical course and histopathology of hepatitis E. In immunocompetent patients, hepatitis E usually follows an asymptomatic or subclinical course, but may also present with acute hepatitis. In contrast, immunocompromised patients may develop chronic hepatitis, and patients with preexisting liver diseases are at risk for liver decompensation with potentially fatal outcome. Whereas pathologists only occasionally encounter liver biopsies from immunocompetent individuals with hepatitis E, they are more likely exposed to biopsies from patients with preexisting liver disease or immunocompromised individuals. Histopathologic hallmarks of hepatitis E in immunocompetent patients comprise lobular disarray, lobular, and portal inflammation, as well as hepatocyte necrosis of varying extend and regeneration. Thus, it is similar to acute non-E viral hepatitis, yet further differential diagnoses include autoimmune hepatitis and drug-induced liver injury. Histopathologic findings of hepatitis E in preexisting liver disease are determined by the underlying pathology, but may be more severe. Histopathologic presentation of hepatitis E in immunocompromised patients is highly variable, ranging from minimal active hepatitis to chronic hepatitis with severe activity and progressive fibrosis. Taken together, the variability of the histologic features depending on the clinical context and the overlap with other liver diseases make the histopathologic diagnosis of hepatitis E challenging. Immunohistochemistry for HEV open reading frame 2 protein and molecular testing for HEV RNA are useful tissue-based ancillary tools.

First Detection of Hepatitis E Virus in Shellfish and in Seawater from Production Areas in Southern Italy

Shellfish samples (n = 384) from production areas, water samples from the same areas (n = 39) and from nearby sewage discharge points (n = 29) were analyzed for hepatitis E virus (HEV) by real-time and nested RT-PCR. Ten shellfish samples (2.6%) and five seawater samples (12.8%) tested positive for HEV; all characterized strains were G3 and showed high degree of sequence identity. An integrated surveillance in seafood and waters is relevant to reduce the risk of shellfish-associated illnesses.

Incidence and Molecular Characterization of Hepatitis E Virus from Swine in Eastern Cape, South Africa

Hepatitis E virus-mediated infection is a serious public health concern in economically developing nations of the world. Globally, four major genotypes of HEV have been documented. Hepatitis E has been suggested to be zoonotic owing to the increase of evidence through various studies. Thus far, this paper reports on prevalence of hepatitis E virus among swine herd in selected communal and commercial farms in the Eastern Cape Province of South Africa. A total of 160 faecal samples were collected from swine herds in Amathole and Chris Hani District Municipalities of Eastern Cape Province for the presence of HEV. Of the 160 faecal samples screened, only seven were positive (4.4%) for HEV. The nucleotide sequences analyses revealed the isolates as sharing 82% to 99% identities with other strains (KX896664, KX896665, KX896666, KX896667, KX896668, KX896669, and KX896670) from different regions of the world. We conclude that HEV is present among swine in the Eastern Cape Province, albeit in low incidence, and this does have public health implications. There is a need for maintenance of high hygienic standards in order to prevent human infections through swine faecal materials and appropriate cooking of pork is highly advised.

Characteristics of 20 Patients with Autochthonous Acute Hepatitis E in Hokkaido, Japan: First Report of Bilateral Facial Palsy Following the Infection with Genotype 4 Hepatitis E Virus

Autochthonous hepatitis E is increasingly being recognized in industrialized countries, including Japan. Although neurological abnormalities have been sporadically reported as an extrahepatic manifestation of hepatitis E virus (HEV) infection, it is rare and has not been reported in Japan. The present study aimed to characterize a total of 20 patients consecutively diagnosed with sporadic acute hepatitis E at a city hospital in Hokkaido, Japan, during 2001-2014, focusing on a patient complicated with neuropathy. Seventeen patients were infected with genotype 4 HEV, while the remaining three patients were with genotype 3 HEV. Although a 67-year-old male with severe hepatitis did not have predisposing factors associated with the development of neurological disorders, such as diabetes mellitus and the use of immunosuppressive agents, he developed bilateral peripheral facial palsy six days after admission. A neurological examination revealed the inability to smile, frown, close his eyes completely or puff out his cheeks. MRI brain scans were considered to be normal. Although it took 83 days after admission for the total bilirubin levels to normalize, his neurological symptoms resolved gradually within three weeks without any sequelae following conservative therapy. A full-length genomic analysis of the HEV strain (HE-JA30) isolated from the patient belonged to genotype 4 and was closest to that currently circulating in Hokkaido, Japan. This is the first report of HEV-associated neuropathy in Japan. While all of previous reports on HEV-related neuropathy involve genotype 3 HEV, the present report is unique in that genotype 4 HEV is responsible for the neuropathy.

Recent Trend of Hepatitis E Virus Infection in Chiba Area, Japan: 3 of 5 Cases with Rheumatoid Arthritis

Hepatitis E virus (HEV) infection is an emerging health concern in developing and developed countries, such as Japan. Five cases have recently been diagnosed as hepatitis E. Of interest, 3 of them had rheumatoid arthritis (RA), although a previous study demonstrated a lack of association between HEV and RA. One of the other patients developed autoimmune hepatitis and was successfully treated with corticosteroids approximately 150 days after the diagnosis of hepatitis E. In RA patients with liver dysfunction, the presence of HEV infection should be evaluated immediately because these patients are often relatively old. Further investigation of the association between HEV and autoimmune hepatitis is needed.

Extra-hepatic manifestations associated with hepatitis E virus infection: a comprehensive review of the literature

Background and aims: Hepatitis E virus (HEV) infection is a significant public health problem that afflicts almost 20 million individuals annually and causes acute liver injury in 3.5 million, with approximately 56 000 deaths. As with other viral hepatitides, extra-hepatic manifestations could represent an important aspect of this infection. The spectrum of these manifestations is still emerging. Acute pancreatitis and neurological, musculoskeletal, hematological, renal, and other immune-mediated manifestations have been described. The aim of this article is to comprehensively review the published literature of extra-hepatic manifestations associated with HEV infection.

Data sources: We searched the PubMed database using the MeSH term “hepatitis E” and each of the extra-hepatic manifestations associated with HEV infection. No language or date restrictions were set in these searches. Searches retrieving articles with non-A, non-B hepatitis were excluded. Additional articles were identified through the reference lists of included articles.

Results: Several extra-hepatic manifestations associated with HEV infection have been published. The temporal association between some extra-hepatic manifestations and HEV infection and the exclusion of other possible etiologies suggests that HEV infection could have caused some of them. According to the available data, HEV infection appears to be strongly associated with acute pancreatitis, neurological disorders (with primarily dominant peripheral nerve involvement, most commonly manifested as Guillain-Barré syndrome, followed by neuralgic amyotrophy), hematological diseases (hemolytic anemia due to glucose phosphate dehydrogenase deficiency, and severe thrombocytopenia), glomerulonephritis, and mixed cryoglobulinemia. More data are needed to clarify whether an association exists with musculoskeletal or other immune-mediated manifestations.

Conclusions: HEV infection should be considered in patients with acute pancreatitis, Guillain-Barré syndrome, neuralgic amyotrophy, hemolytic anemia due to glucose phosphate dehydrogenase deficiency, severe thrombocytopenia, glomerulonephritis, and mixed cryoglobulinemia. Alternatively, signs and symptoms of these conditions should be sought in patients with acute or chronic HEV infection. More data are needed to confirm the role of HEV in other extra-hepatic disorders.