Acute hepatitis E in south-west France over a 5-year period

Active surveillance of hepatitis E: a 10-year epidemiological analysis in a city in eastern China

Hepatitis E virus (HEV) is an important cause of acute hepatitis, however, is highly neglected and largely underreported. This study aimed to describe the detailed epidemiology of hepatitis E (HE) through a 10-year surveillance. A community-based active hepatitis surveillance was conducted between November 2007 and October 2017 in 11 townships of Dongtai City in China, involving 355,673 residents. Serum samples were obtained from patients presenting with hepatitis symptoms for more than 3 days. Serum alanine aminotransferase (ALT) levels greater than 2.5 times the upper limit of normal (ULN) were considered acute hepatitis. Samples were subsequently tested for IgG and IgM anti-HEV antibodies, HEV RNA, and hepatitis B surface antigen (HBsAg). The data indicated the incidence of HE fluctuated downward from 2007 to 2017, with an average annual age-standardized incidence of 17.50 per 100,000, exceeding the 10.26 per 100,000 in the National Notifiable Disease Report System (NNDRS). The incidence was notably higher among males (20.95 per 100,000) and individuals aged 50-69 years (37.47 per 100,000). Genotype 4 (HEV-4) was the predominantly circulating genotype during the study period. Furthermore, the study revealed the incidence of hepatitis with HEV and hepatitis B virus (HBV) co-infection was 4.99 per 100,000. The active surveillance system identified a higher incidence of HE compared to NNDRS, with a decreased prevalence over a 10-year period. While efforts are still needed to prevent HE in high-risk populations, including individuals with hepatitis B and the elderly.

Spatial-temporal analysis of hepatitis E in Hainan Province, China (2013-2022): insights from four major hospitals

Objective

Exploring the Incidence, Epidemic Trends, and Spatial Distribution Characteristics of Sporadic Hepatitis E in Hainan Province from 2013 to 2022 through four major tertiary hospitals in the Province.

Methods

We collected data on confirmed cases of hepatitis E in Hainan residents admitted to the four major tertiary hospitals in Haikou City from January 2013 to December 2022. We used SPSS software to analyze the correlation between incidence rate and economy, population density and geographical location, and origin software to draw a scatter chart and SAS 9.4 software to conduct a descriptive analysis of the time trend. The distribution was analyzed using ArcMap 10.8 software (spatial autocorrelation analysis, hotspot identification, concentration, and dispersion trend analysis). SAS software was used to build an autoregressive integrated moving average model (ARIMA) to predict the monthly number of cases in 2023 and 2024.

Results

From 2013 to 2022, 1,922 patients with sporadic hepatitis E were treated in the four hospitals of Hainan Province. The highest proportion of patients (n = 555, 28.88%) were aged 50-59 years. The annual incidence of hepatitis E increased from 2013 to 2019, with a slight decrease in 2020 and 2021 and an increase in 2022. The highest number of cases was reported in Haikou, followed by Dongfang and Danzhou. We found that there was a correlation between the economy, population density, latitude, and the number of cases, with the correlation coefficient |r| value fluctuating between 0.403 and 0.421, indicating a linear correlation. At the same time, a scatter plot shows the correlation between population density and incidence from 2013 to 2022, with r2 values fluctuating between 0.5405 and 0.7116, indicating a linear correlation. Global Moran's I, calculated through spatial autocorrelation analysis, showed that each year from 2013 to 2022 all had a Moran's I value >0, indicating positive spatial autocorrelation (p < 0.01). Local Moran's I analysis revealed that from 2013 to 2022, local hotspots were mainly concentrated in the northern part of Hainan Province, with Haikou, Wenchang, Ding'an, and Chengmai being frequent hotspot regions, whereas Baoting, Qiongzhong, and Ledong were frequent cold-spot regions. Concentration and dispersion analysis indicated a clear directional pattern in the average density distribution, moving from northeast to southwest. Time-series forecast modeling showed that the forecast number of newly reported cases per month remained relatively stable in 2023 and 2024, fluctuating between 17 and 19.

Conclusion

The overall incidence of hepatitis E in Hainan Province remains relatively stable. The incidence of hepatitis E in Hainan Province increased from 2013 to 2019, with a higher clustering of cases in the northeast region and a gradual spread toward the southwest over time. The ARIMA model predicted a relatively stable number of new cases each month in 2023 and 2024.

Prevalence, Genetic Diversity, and Quantification of the RNA Genome of the Hepatitis E Virus in Slaughtered Pigs in Serbia

The goal of this study conducted in Serbia was to detect HEV in pig liver samples from slaughterhouses, retail outlets, and environmental swabs over the course of a year. All positive HEV samples were measured and expressed as HEV gene copy numbers per gram of sample, and a representative number of samples were sequenced using the Sanger approach. A total of 45 HEV-positive samples were re-amplified using nested RT-PCR employing CODEHOP primers targeting ORF2 (493 nucleotides). The average prevalence of the HEV genotype 3 in all pig liver samples from the slaughterhouses was 29%, while HEV prevalence was 44% in liver samples from animals younger than 3 months. HEV RNA was found in thirteen out of sixty (22%) environmental swab samples that were taken from different surfaces along the slaughter line. Our findings confirmed seasonal patterns in HEV prevalence, with two picks (summer and winter periods) during the one-year examination. Among HEV-positive samples, the average viral particles for all positive liver samples was 4.41 ± 1.69 log10 genome copies per gram. Phylogenetic analysis revealed the majority of HEV strains (43/45) from Serbia were grouped in the HEV-3a subtype, while two strains were classified into the HEV-3c subtype, and one strain could not be classified into any of the HEV-3 subtypes.

Age and Gender Trends in the Prevalence of Markers for Hepatitis E Virus Exposure in the Heterogeneous Bulgarian Population

The prevalence of hepatitis E virus (HEV) in the Bulgarian population remains underestimated. The aim of the present study was to evaluate age and gender trends in HEV prevalence in the heterogeneous Bulgarian population. Stored serum samples from blood donors and different patient sub-populations-kidney recipients (KR), patients with Guillain-Barre syndrome (GBS), Lyme disease (LD), patients with liver involvement and a clinical diagnosis other than viral hepatitis A and E (non-AE), hemodialysis (HD) and HIV-positive patients (HIV)-were retrospectively investigated for markers of past and recent/ongoing HEV infection. The estimated overall seroprevalence of past infection was 10.6%, ranging from 5.9% to 24.5% for the sub-populations evaluated, while the seroprevalence of recent/ongoing HEV infection was 7.5%, ranging from 2.1% to 20.4%. The analysis of the individual sub-populations showed a different prevalence with respect to sex. In regard to age, the cohort effect was preserved, as a multimodal pattern was observed only for the GBS sub-population. Molecular analysis revealed HEV 3f and 3e. The type of the population is one of the main factors on which the anti-HEV prevalence depends, highlighting the need for the development of guidelines related to the detection and diagnosis of HEV infection with regard to specific patient populations.

Treatment Options for Hepatitis A and E: A Non-Systematic Review

Hepatitis A and hepatitis E are relatively common causes of liver disease. Both viruses are mainly transmitted through the faecal-oral route and, consequently, most outbreaks occur in countries with poor sanitation. An important role of the immune response as the driver of liver injury is also shared by the two pathogens. For both the hepatitis A (HAV) and hepatitis E (HEV) viruses, the clinical manifestations of infection mainly consist of an acute disease with mild liver injury, which results in clinical and laboratory alterations that are self-limiting in most cases. However, severe acute disease or chronic, long-lasting manifestations may occur in vulnerable patients, such as pregnant women, immunocompromised individuals or those with pre-existing liver disease. Specifically, HAV infection rarely results in fulminant hepatitis, prolonged cholestasis, relapsing hepatitis and possibly autoimmune hepatitis triggered by the viral infection. Less common manifestations of HEV include extrahepatic disease, acute liver failure and chronic HEV infection with persistent viraemia. In this paper, we conduct a non-systematic review of the available literature to provide a comprehensive understanding of the state of the art. Treatment mainly consists of supportive measures, while the available evidence for aetiological treatment and additional agents in severe disease is limited in quantity and quality. However, several therapeutic approaches have been attempted: for HAV infection, corticosteroid therapy has shown outcome improvement, and molecules, such as AZD 1480, zinc chloride and heme oxygenase-1, have demonstrated a reduction in viral replication in vitro. As for HEV infection, therapeutic options mainly rely on the use of ribavirin, and some studies utilising pegylated interferon-alpha have shown conflicting results. While a vaccine for HAV is already available and has led to a significant reduction in the prevalence of the disease, several vaccines for HEV are currently being developed, with some already available in China, showing promising results.

Severe hepatitis E infection in pregnancy: a case report

Hepatitis E virus causes self limiting hepatitis most of the times but, during pregnancy it can lead to severe hepatitis along with various complications thereby increasing the mortality.

Case presentation

A 27-year-old woman gravida two, para one at 38 weeks and 6 days of gestation presented with multiple episodes of nonbilious vomiting, severe dehydration, and later developed right upper quadrant abdominal pain. The patient had a positive serological test for the hepatitis E virus, and liver enzymes were severely elevated. Under supportive treatment she delivered a healthy baby, and her liver enzymes returned to normal levels after 2 weeks of delivery.

Clinical discussion

Although the hepatitis E virus usually causes self-limiting hepatitis, it can quickly progress to severe hepatitis, liver failure, and even death during pregnancy. Immunological change with a Th2 biased response and increased hormonal levels during pregnancy could possibly facilitate the development of severe liver damage. No particular drug has been approved for the treatment of hepatitis E viral infection in pregnant women, and the commonly used drugs are contraindicated due to the risk of teratogenicity. Supportive therapy and intensive monitoring are the core management techniques for hepatitis E virus infection in pregnant women.

Conclusion

Due to the high mortality risk, pregnant women should try to avoid possible exposure to the hepatitis E virus, but once infected, symptomatic therapy is the mainstay.

Seven years (2015-2021) of blood donor screening for HEV-RNA in France: lessons and perspectives

BACKGROUND

The French health authorities are considering expanding the current selective hepatitis E virus (HEV)-RNA testing procedure to include all donations in order to further reduce transfusion-transmitted HEV infection. Data obtained from blood donors (BDs) tested for HEV-RNA between 2015 and 2021 were used to assess the most efficient nucleic acid testing (NAT) strategy.

MATERIALS AND METHODS

Viral loads (VLs) and the plasma volume of blood components, as well as an HEV-RNA dose of 3.85 log IU as the infectious threshold and an assay with a 95% limit of detection (LOD) at 17 IU/mL, were used to assess the proportion of: (i) HEV-RNA-positive BDs that would remain undetected; and (ii) blood components associated with these undetected BDs with an HEV-RNA dose >3.85 log IU, considering 4 NAT options (Individual testing [ID], MP-6, MP-12, and MP-24).

RESULTS

Of the 510,118 BDs collected during the study period, 510 (0.10%) were HEV-RNA-positive. Based on measurable VLs available in 388 cases, 1%, 15.2%, 21.8%, and 32.6% of BDs would theoretically pass undetected due to a VL below the LOD of ID, MP-6, MP-12, and MP-24 testing, respectively. All BDs associated with a potentially infectious blood component would be detected with ID-NAT while 13% of them would be undetected with MP-6, 19.6% with MP-12, and 30.4% with MP-24 depending on the plasma volume. No red blood cell (RBC) components with an HEV-RNA dose >3.85 log IU would enter the blood supply, regardless of the NAT strategy used.

DISCUSSION

A highly sensitive ID-NAT would ensure maximum safety. However, an MP-based strategy can be considered given that: (i) the risk of transmission is closely related to the plasma volume of blood components; (ii) RBC are the most commonly transfused components and have a low plasma content; and (iii) HEV-RNA doses transmitting infection exceed 4 log IU. To minimise the potential risk associated with apheresis platelet components and fresh frozen plasma, less than 12 donations should be pooled using an NAT assay with a LOD of approximately 20 IU/mL.

Hepatitis E virus infection in the United States: Seroprevalence, risk factors and the influence of immunological assays

In the United States (U.S.), a hepatitis E virus (HEV) seroprevalence between 6 and 21% has been described, with a decreasing trend. We aimed to investigate HEV infection in the U.S. population from 2009 to 2016, and examine the differences in seroprevalence using different assays. We used data from the National Health and Nutrition Examination Survey (NHANES-CDC) to estimate HEV seroprevalence and analyze demographic variables related to the infection. Additionally, we compared 4 serological tests used. The estimated HEV seroprevalence between 2009-2016 was 6.1% (95% CI: 5.6%-7.0%) for IgG and 1.02% (0.8%-1.2%) for IgM. Higher HEV IgG prevalences were found in older people, females, non-Hispanic Asians and those born outside of the U.S. The in-house immunoassay and the Wantai HEV-IgG ELISA presented the highest sensitivity values in the tested population. The highest specificity values corresponded to the DSI-EIA-ANTI-HEV-IgG assay. The kappa statistical values showed concordances no greater than 0.64 between the assays. HEV prevalence in our study was similar to previously reported, and a decline in the prevalence was observed through the NHANES assessments (from 1988 to 2016). The sensitivity and specificity of the assays varied widely, making comparisons difficult and highlighting the need to develop a gold standard assay.

Hepatitis E Virus Infection: Neurological Manifestations and Pathophysiology

Hepatitis E virus (HEV) is the first cause of viral hepatitis in the world. While the water-borne HEV genotypes 1 and 2 are found in developing countries, HEV genotypes 3 and 4 are endemic in developed countries due to the existence of animal reservoirs, especially swine. An HEV infection produces many extra-hepatic manifestations in addition to liver symptoms, especially neurological disorders. The most common are neuralgic amyotrophy or Parsonage–Turner syndrome, Guillain–Barré syndrome, myelitis, and encephalitis. The pathophysiology of the neurological injuries due to HEV remains uncertain. The immune response to the virus probably plays a role, but direct virus neurotropism could also contribute to the pathophysiology. This review describes the main neurological manifestations and their possible pathogenic mechanisms.

Case-Control Study of Risk Factors for Acquired Hepatitis E Virus Infections in Blood Donors, United Kingdom, 2018-2019

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis in England. Substantial yearly increases of autochthonous infections were observed during 2003–2016 and again during 2017–2019. Previous studies associated acute HEV cases with consumption of processed pork products, we investigated risk factors for autochthonous HEV infections in the blood donor population in England. Study participants were 117 HEV RNA–positive blood donors and 564 HEV RNA–negative blood donors. No persons with positive results were vegetarian; 97.4% of persons with positive results reported eating pork products. Consuming bacon (OR 3.0, 95% CI 1.7–5.5; p<0.0001), cured pork meats (OR 3.5, 95% CI 2.2–5.4; p<0.0001), and pigs’ liver (OR 2.9, 95% CI 1.0–8.3; p = 0.04) were significantly associated with HEV infection. Our findings confirm previous links to pork products and suggest that appropriate animal husbandry is essential to reduce the risk for HEV infection.

Assessment of subclinical effects of Hepatitis E virus infection in the United States

Some studies have exposed an increase in liver cirrhosis in hepatitis E seropositive individuals living with human immunodeficiency virus. The interrelation between HEV seroprevalence and risk of liver disease in immune-competent individuals remains under- investigated. Using the National Health and Nutrition Examination Survey (NHANES) data containing >30,000 subjects, we addressed if HEV exposure leads to subclinical effects that can influence liver health. We determined the association between HEV IgM and ALT and that of HEV IgG and Fib-4-a composite score reflecting potential liver fibrosis. These analyses were repeated in populations at risk for liver disease as well as among different races and ethnicities. The prevalence of HEV IgG was significantly associated with age as IgG positive individuals were, on average, 20 years older than IgG negative patients. We found a statistically significant increase in the likelihood of having a Fib-4 score >1.45 (significant fibrosis) in those positive for HEV IgG (RR: 1.03; 95% CI: 1.01-1.05). However, due to the small effect, it is unlikely that this association has clinical significance. Moreover, the effect was not present in those with pre-existing liver disease. We found no association between ALT levels and the presence of HEV IgM or IgG. This is the first study examining subclinical effects of HEV infection in the United States. Our study found that in the general US population, predominantly asymptomatic HEV infections do not contribute to the overall burden of liver disease.

Serological and molecular study of Hepatitis E virus in pediatric patients in Mexico

INTRODUCTION AND OBJECTIVES

Cases of viral hepatitis reported in Mexico are typically identified as hepatitis A, B and C. However, unspecified cases are reported annually. Hepatitis E virus (HEV) is an emergent agent that causes a self-limiting infection that can evolve to chronic in immunosuppressed individuals. In Mexico, HEV genotype 2 is considered endemic, though it's the prevalence is not well known. Therefore, the present study was designed to determine the prevalence of HEV among patients at the "Hospital Infantil de Mexico Federico Gomez".

MATERIALS AND METHODS

The study included 99 patients, anti-HEV antibody (IgG and IgM) were detected by indirect ELISA and viral genome was identified using RT-PCR technique. Two PCR products of positive cases were sequenced.

RESULTS

ELISA results were positive in 3% and 6%, for IgG and IgM respectively, 54.5% prevalence was found by PCR. Low lymphocyte count (p<0.05) and malnutrition (p<0.005) were significant factors for high PCR prevalence and could increase the possibility of infection. Two samples were sequenced and confirmed the presence of HEV genotype 3.

CONCLUSIONS

This report reveals the incidence of HEV in pediatric patients in Mexico. Moreover, the identification of HEV genotype 3 in human samples suggests a potential zoonotic risk that requires further research.

Hepatitis E, what is the real issue?

Hepatitis E virus (HEV) infection is a worldwide disease and the primary cause of acute viral hepatitis with an estimated 3.3 million symptomatic cases every year and 44,000 related deaths. It is a waterborne infection in the developing countries. In these countries, HEV genotypes 1 and 2 cause large outbreaks and affect young subjects resulting in significant mortality in pregnant women and patients with cirrhosis. In developed countries, HEV genotypes 3 and 4 are responsible for autochthonous, sporadic hepatitis and transmission is zoonotic. Parenteral transmission by the transfusion of blood products has been identified as a potential new mode of transmission. HEV can also cause neurological disorders and chronic infections in immunocompromised patients. The progression of acute hepatitis E is usually asymptomatic and resolves spontaneously. Diagnosis is based on both anti-HEV IgM antibodies in serum and viral RNA detection in blood or stools by PCR in immunocompetent patients, while only PCR is validated in immunocompromised individuals. Ribavirin is the only validated treatment in chronic infection. A vaccine has been developed in China.

Widespread rash as initial presentation of acute hepatitis E in a woman with well-controlled HIV

Sporadic, acute hepatitis E is increasingly common in the United Kingdom, associated with travel or locally acquired. A 45-year-old woman with well-controlled HIV presented with a widespread, polymorphic rash and transaminitis. Acute genotype 3 hepatitis E infection was confirmed and resolved without intervention. A review of the literature reveals a number of atypical presentations of acute autochthonous hepatitis E. Clinicians should consider testing for hepatitis E in the presence of nonspecific symptoms and deranged liver function tests.

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.

Hepatitis E virus infection during pregnancy

BACKGROUND

Hepatitis E virus (HEV) generally causes self-limiting viral hepatitis. However, in pregnant women, HEV infection can be severe and has been associated with up to 30% mortality in the third trimester. Additionally, HEV infection in pregnancy is also associated with high rates of preterm labor and vertical transmission.

MAIN BODY

HEV is now recognized as a global health problem in both developing and industrialized countries. HEV can be transmitted via the fecal-oral route, zoonotic route, and blood transfusion route. An altered immune status, hormonal levels, and viral factors may be related to the severity of the disease. Currently, no established treatment is available for HEV in pregnant women. A Chinese vaccine has been demonstrated to be protective against HEV in the general population and seems to be safe in pregnancy; however, its safety and efficacy in a large population of pregnant women remain to be determined.

CONCLUSION

This review summarizes the current knowledge about HEV infection during pregnancy and focuses on the epidemiology, clinical manifestations, mechanisms underlying severe liver injury, and management and prevention of HEV infection during pregnancy. Considering that HEV infection during pregnancy may result in poor outcomes, screening for and monitoring HEV infection early in pregnancy should be taken into account. In addition, a better understanding of the pathogenesis will help to develop potential treatment strategies targeting HEV infection in pregnancy.

Hepatitis E, what's the real issue?

Hepatitis E Virus (HEV) infection is a worldwide disease and the primary cause of acute viral hepatitis in the world with an estimated 20 million cases every year and 70 000 deaths. Hepatitis E is a waterborne infection in the developing countries. In these countries, HEV genotypes 1 and 2 cause large outbreaks and affect young subjects, resulting in significant mortality in pregnant women and patients with cirrhosis. In the developed countries, HEV genotypes 3 and 4 are responsible for autochthonous, sporadic hepatitis and transmission is zoonotic. Parenteral transmission by the transfusion of blood products has been identified as a potential new mode of transmission. The prevalence of positive HEV viraemia in blood donors in Europe ranges from 1/600 to 1/2500 in highly endemic European countries. HEV can cause neurological disorders and chronic infections in immunocompromised patients. The progression of acute hepatitis E is usually asymptomatic and resolves spontaneously. Diagnostic tools include anti-HEV IgM antibodies in serum and/or viral RNA detection in the blood or the stools by PCR. Ribavirin is used to treat chronic infection. A vaccine has been developed in China.

Natural viral co-infections in pig herds affect hepatitis E virus (HEV) infection dynamics and increase the risk of contaminated livers at slaughter

Hepatitis E virus (HEV) is a zoonotic pathogen, in particular genotype 3 HEV is mainly transmitted to humans through the consumption of contaminated pork products. This study aimed at describing HEV infection patterns in pig farms and at assessing the impact of immunomodulating co-infections namely Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Circovirus Type 2 (PCV2), as well as other individual factors such as piglets' immunity and litters' characteristics on HEV dynamics. A longitudinal follow-up was conducted in three farrow-to-finish farms known to be HEV infected. Overall, 360 piglets were individually monitored from birth to slaughter with regular blood and faecal sampling as well as blood and liver samples collected at slaughterhouse. Virological and serological analyses were performed to detect HEV, PCV2 and PRRSV genome and antibodies. The links between 12 explanatory variables and four outcomes describing HEV dynamics were assessed using cox-proportional hazard models and logistic regression. HEV infection dynamics was found highly variable between farms and in a lower magnitude between batches. HEV positive livers were more likely related to short time-intervals between HEV infection and slaughter time (<40 days, OR = 4.1 [3.7-4.5]). In addition to an influence of piglets' sex and sows' parity, the sequence of co-infections was strongly associated with different HEV dynamics: a PRRSV or PCV2/PRRSV pre- or co-infection was associated with a higher age at HEV shedding (Hazard Ratio = 0.3 [0.2-0.5]), as well as a higher age at HEV seroconversion (HR = 0.5 [0.3-0.9] and HR = 0.4 [0.2-0.7] respectively). A PCV2/PRRSV pre- or co-infection was associated with a longer duration of shedding (HR = 0.5 [0.3-0.8]). Consequently, a PRRSV or PCV2/PRRSV pre- or co-infection was strongly associated with a higher risk of having positive livers at slaughter (OR = 4.1 [1.9-8.9] and OR = 6.5 [3.2-13.2] respectively). In conclusion, co-infections with immunomodulating viruses were found to affect HEV dynamics in the farrow-to-finish pig farms that were followed in this study.

Acute sporadic hepatitis E in the Zhejiang coastal area of China: a 14-year hospital-based surveillance study

BACKGROUND

To examine the epidemiological trends and changes of hepatitis E virus (HEV) infection and the potential risk factors for severe infection in the Zhejiang eastern coastal area of China.

METHODS

We analyzed statutory hepatitis E cases notifications and inpatient data held by the national surveillance and hospital information systems in Wenzhou, Taizhou, Ningbo, and Zhoushan cities of the Zhejiang eastern coastal area of China.

RESULTS

Nine thousand four hundred sixteen hepatitis E cases were reported from 2004 to 2017, with an average incidence of 2.94 per 100,000. The overall death rate was 0.06% (6/9416). A gradual decline of hepatitis E cases was found in the coastal areas since 2007, while a rise was identified in the non-coastal areas. Annual incidence in non-coastal cities was much higher than that in coastal cities (4.345 vs. 2.945 per 100,000, relative risk = 1.5, P value < 0.001). The mean age was 52 years old and 50.55 years with a male-to-female ratio of 2.32:1 and 2.21:1 in coastal and noncoastal areas respectively (all P > 0.05). Hepatitis E cases prevalence increased with age, highest among men in their 70s (9.02 vs. 11.33 per 100,000) and women in their 60s (3.94 vs. 4.66 per 100,000) groups for both coastal and noncoastal areas respectively. A clear seasonal pattern was observed, with a peak in March (0.4429 per 100,000) in coastal areas. 202 inpatients were documented, of which 50.50% (102/202) were severe cases. Male individuals with alcohol consumption, alcohol hepatic diseases, and superinfection were the three independent highest risks for severe infections (all with P value < 0.05).

CONCLUSIONS

This is to our knowledge the largest epidemiological study of hepatitis E cases in the eastern coastal area of Zhejiang province of China. The patterns of infection across the coastal areas were similar to those of the non-coastal areas, but the incidence was substantially lower and decreased gradually since 2007.

Human hepatitis E virus circulation in Bulgaria: Deep Bayesian phylogenetic analysis for viral spread control in the country

Hepatitis E virus (HEV) infection in Bulgaria is endemic, as demonstrated by the seroprevalence of antibody against the virus in the general population and by the high prevalence of clinical cases registered. In this study, a deep Bayesian phylogenetic analysis has been performed to provide information on the genetic diversity and the spread of HEV genotypes in Bulgaria. Three different data sets of HEV virus was built for genotyping by the maximum likelihood method, for evolutionary rate estimated by Bayesian Markov Chain Monte Carlo approach, for demographic history investigation and for selective pressure analysis. The evolutionary rate for genotype 3e, was 351 × 10^-3 substitution/site/year (95% highest posterior density [95% HPD]: 145 × 10 ^-3 -575 × 10 ^-3 ). The root of the time to the most recent common ancestor of the Bayesian maximum clade credibility tree of HEV 3e genotype corresponded to 1965 (HPD 95% 1949-1994). The Bulgarian sequences mainly clustered in the main clade (clade A). The monophyletic clade included all Bulgarian genotype 3e sequences. The demographic history showed a slight growth from 1995 to 2000, followed by a sort of bottleneck in 2010s, a peak in 2011 and a new growth to 2015. Selection pressure analysis did not show sites under positive pressure but 64 statistically significant sites under negative selection. Molecular epidemiological surveillance by Bayesian phylogeny of HEV virus can contribute to trace the way of human infection after contact with swine source directly or heating meat improving public health control.

Classification and Epidemiologic Aspects of Acute Liver Failure

Acute liver failure is a rare condition with high short-term morbidity and mortality. The most widely accepted definition is an abnormality in coagulation with any degree of encephalopathy in a patient without cirrhosis and an illness duration of less than 26 weeks. Multiple classifications systems are currently in use to help categorize the condition. This article reviews the most commonly used systems. The epidemiologic aspects of the disease are also reviewed, including incidence, prevalence, demographics, geographic distribution, and racial and cultural factors and are discussed for the various subtypes of acute liver failure.

Prevalence of hepatitis E virus infection in wild boars from Spain: a possible seasonal pattern?

BACKGROUND

It has been shown that wildlife can serve as natural reservoirs of hepatitis E virus (HEV). The wild boar (Sus scrofa) is probably the main natural reservoir of HEV and could therefore represent an important route of transmission in Europe, especially in regions where game meat is widely consumed. We evaluated the prevalence of HEV infection in wild boar in the south of Spain, with the aim of identifying associated risk factors. A cross-sectional study that included hunted wild boar was carried out during the 2015/2016 hunting season (October 15 to February 15) in Andalusia (southern Spain). The outcome variable was HEV infection, defined as amplification of HEV RNA in serum by RT-PCR.

RESULTS

A total of 142 animals, selected from 12 hunting areas, were included and formed the study population. Thirty-three wild boars (23.2%; 95% CI: 16.8%-30.7%) were positive for HEV infection. Prevalence peaked in October and November, then gradually declined until the end of December. After multivariate analysis, only hunting date was independently associated with HEV infection across sex and age.

CONCLUSIONS

Our study found a relatively high prevalence of HEV infection in wild boar in the south of Spain, suggesting that prevalence may depend on the season when the animal is hunted. In consequence, the potential risk of zoonotic transmission could fluctuate.

Rabbit Hepatitis E Virus Infections in Humans, France

Hepatitis E virus (HEV) has been detected in rabbits, but whether rabbit HEV strains can be transmitted to humans is not known. Of 919 HEV-infected patients in France during 2015-2016, five were infected with a rabbit HEV strain. None of the patients had direct contact with rabbits, suggesting foodborne or waterborne infections.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

Hepatitis E virus seroprevalence among the general population in a livestock-dense area in the Netherlands: a cross-sectional population-based serological survey

Background

Recent serological studies indicate that hepatitis E virus (HEV) is endemic in industrialised countries. The increasing trend in the number of autochthonous cases of HEV genotype 3 in Western European countries, stresses the importance to get insight in the exact routes of exposure. Pigs are the main animal reservoir, and zoonotic food-borne transmission of HEV is proven. However, infected pigs can excrete large amounts of virus via their faeces enabling environmental transmission of HEV to humans. This might pose a risk for of neighbouring residents of livestock farming.

Methods

Within a large study on the health of people living in the vicinity of livestock farming we performed a cross-sectional population-based serological survey among 2,494 non-farming adults from the general population in a livestock-dense area in the south of the Netherlands. Participants completed risk factor questionnaires and blood samples of 2,422 subjects (median age 58 years, range 20–72) were tested for anti-HEV IgG using an enzyme immune assay (Wantai). The aim of this study was to determine the HEV seroprevalence and to assess whether seropositivity in adults was associated with living in the vicinity of pig farms.

Results

The average seroprevalence of HEV was 28.7% (95% CI: 26.9–30.5). Determinants associated with an increased risk for HEV seropositivity were male gender and low level of education. There was a clear trend of increasing prevalence with increasing age (Chi-square test for linear trend, X² = 83.1; p < 0.001). A high number of pigs within 1,000 m of the residential address was not a risk factor for seropositivity.

Conclusions

This study confirmed the high HEV seroprevalence (29%) in the general population of the Netherlands, but presence of antibodies was not associated with residential proximity to pig farms. The prevalence increased with age from 10% in adolescents to 33% among those aged 50 and above, supporting the assumption of a cumulative lifetime exposure to HEV in the Netherlands as well as a higher infection pressure in the past. Our findings cannot refute the assumption that transmission is primarily food-borne.

Hepatitis E Pathogenesis

Although most hepatitis E virus (HEV) infections are asymptomatic, some can be severe, causing fulminant hepatitis and extra-hepatic manifestations, including neurological and kidney injuries. Chronic HEV infections may also occur in immunocompromised patients. This review describes how our understanding of the pathogenesis of HEV infection has progressed in recent years.

Low transfusion transmission of hepatitis E among 25,637 single-donation, nucleic acid-tested blood donors

BACKGROUND

Hepatitis E virus genotype-3 (HEV-gt-3) causes autochthonous infections in western countries, with a primary reservoir in animals, especially pigs. HEV transfusion transmission has been reported, and HEV-gt-3 prevalence is high in some European countries. The prevalence of HEV RNA was investigated among Danish blood donors, and the prevalence of HEV transfusion-transmitted infection (TTI) was investigated among recipients.

STUDY DESIGN AND METHODS

Samples from 25,637 consenting donors collected during 1 month in 2015 were screened retrospectively using an individual-donation HEV RNA nucleic acid test with a 95% detection probability of 7.9 IU/mL. HEV-positive samples were quantified by real-time polymerase chain reaction and genotyped. Transmission was evaluated among recipients of HEV RNA-positive blood components. Phylogenetic analyses compared HEV sequences from blood donors, symptomatic patients, and swine.

RESULTS

Eleven donations (0.04%) were confirmed as positive for HEV RNA (median HEV RNA level, 13 IU/mL). Two donations were successfully genotyped as HEV-gt-3. Only one donor had a travel history outside Europe. Nine of 11 donors were male, but the gender ratio was nonsignificant compared with the total donor population. Seven available recipients tested negative for HEV RNA and anti-HEV immunoglobulin M in follow-up samples. One recipient was HEV RNA-negative but anti-HEV immunoglobulin G-positive. HEV TTI was considered unlikely, but a transfusion-induced secondary immune response could not be excluded. Phylogenetic analysis showed relatively large sequence differences between HEV from donors, symptomatic patients, and swine.

CONCLUSIONS

Despite an HEV RNA prevalence of 0.04% in Danish blood donations, all HEV-positive donations carried low viral loads, and no evidence of TTI was found.

Hepatitis E in Israel: A nation-wide retrospective study

AIM: To investigate the epidemiology, risk factors and clinical course of acute hepatitis E virus (HEV) infection in Israel, an industrialized country.

METHODS: A retrospective analysis of acute HEV cases diagnosed in Israel from 1993 to 2013. Acute HEV was defined by ALT/AST elevation and a positive HEV PCR test or positive anti-HEV-IgM serology. HEV RNA was tested by quantitative reverse transcription PCR. Antibodies to HEV were tested retrospectively using an ELISA assay. HEV-RNA was sequenced using RT-PCR of ORF1 and ORF2 regions to diagnose genotype of the virus. Epidemiologic and clinical data were collected by reviewing the clinical files and through a telephone interview according to a structured questionnaire.

RESULTS: Acute HEV was diagnosed in 68 patients. Among the 59 patients who gave an informed consent and were interviewed, 41% of infections were autochthonous (acquired in Israel), 44% travel-related and 15% imported by foreign workers. Autochthonous patients were mainly females (62.5%), more than half of them pregnant, 26% recalled consuming food or water in areas with poor sanitation, 44% ate non-kosher meat. Fulminant hepatitis developed in 3 patients (5%), all of them were females, two of them with post-partum infection, all acquired the disease in Israel (autochthonous). Israeli travelers with imported infection were predominantly males (73%), acquired the disease in the Indian subcontinent (81%), with 100% reporting having consumed fresh vegetables and drinks with ice cubes abroad. Six patients’ sera were tested for genotype and revealed HEV genotype 1 (all cases acquired in the Indian subcontinent).

CONCLUSION: This is the first report which highlights the existence of hepatitis E as an autochthonous infection in Israel. Imported HEV originates mostly from the Indian subcontinent.

Neurologic Disorders in Immunocompetent Patients with Autochthonous Acute Hepatitis E

Neurologic disorders, mainly Guillain-Barré syndrome and Parsonage–Turner syndrome (PTS), have been described in patients with hepatitis E virus (HEV) infection in industrialized and developing countries. We report a wider range of neurologic disorders in nonimmunocompromised patients with acute HEV infection. Data from 15 French immunocompetent patients with acute HEV infection and neurologic disorders were retrospectively recorded from January 2006 through June 2013. The disorders could be divided into 4 main entities: mononeuritis multiplex, PTS, meningoradiculitis, and acute demyelinating neuropathy. HEV infection was treated with ribavirin in 3 patients (for PTS or mononeuritis multiplex). One patient was treated with corticosteroids (for mononeuropathy multiplex), and 5 others received intravenous immunoglobulin (for PTS, meningoradiculitis, Guillain-Barré syndrome, or Miller Fisher syndrome). We conclude that pleiotropic neurologic disorders are seen in HEV-infected immunocompetent patients. Patients with acute neurologic manifestations and aminotransferase abnormalities should be screened for HEV infection.

A nationwide survey of hepatitis E viral infection in French blood donors

Most cases of hepatitis E viral (HEV) infection in developed countries are autochthonous. Nevertheless, the reported seroprevalence of HEV varies greatly depending on the geographical area and the performance of the immunoassay used. We used validated assays to determine the prevalence of anti-HEV immunoglobulin G (IgG) and IgM among 10,569 French blood donors living in mainland France and three overseas areas. Epidemiological information was collected using a specific questionnaire. We found an overall IgG seroprevalence of 22.4% (8%-86.4%) depending on the geographical area (P < 0.001). The presence of anti-HEV IgG was associated with increasing age (P < 0.001) and eating pork meat (P = 0.03), pork liver sausages (P < 0.001), game meat (P < 0.01), offal (P < 0.001), and oysters (P = 0.02). Conversely, drinking bottled water was associated with a lower rate of anti-HEV IgG (P = 0.02). Overall IgM seroprevalence was 1% (0%-4.6%). The frequency of anti-HEV IgM was higher in donors living in a high anti-HEV IgG seroprevalence area (1.9% versus 0.7%, P < 0.001) and in those eating pork liver sausage (1.4% versus 0.7%, P < 0.01), pâté (1% versus 0.4, P = 0.04), and wild boar (1.3% versus 0.7%, P < 0.01).

CONCLUSION

HEV is endemic in France and hyperendemic in some areas; eating habits alone cannot totally explain the exposure to HEV, and contaminated water could contribute to the epidemiology of HEV infection in France.

Hepatitis E, the neglected one

Hepatitis E virus (HEV) infection is a worldwide disease. It is the first cause of acute viral hepatitis in the world with an estimated 20 million cases every year and 56 000 deaths. In developing countries, hepatitis E is a waterborne infection. In these countries, HEV genotypes 1 and 2 cause large outbreaks and affect young subjects with a significant mortality rate in pregnant women and patients with cirrhosis. In the developed countries, HEV genotypes 3 and 4 are responsible for autochthonous, sporadic hepatitis and transmission is zoonotic. HEV can cause neurological disorders and in immunocompromised patients, chronic infections. The progression of acute hepatitis E is most often mild and resolves spontaneously. Diagnostic tools include anti-HEV IgM antibodies in serum and/or viral RNA in the blood or stools by PCR. Ribavirin is used to treat chronic infection. A vaccine has been developed in China.

Temporal evolution of the distribution of hepatitis E virus genotypes in Southwestern France

Southwest France is a highly endemic region for hepatitis E virus (HEV). This study examined the circulation of HEV strains between 2003 and 2014 in the Midi-Pyrénées, and compared these data with those from the rest of France. The polyproline region (PPR) of the ORF1 region of the HEV genome was also analyzed. HEV genotype was determined by sequencing a 348-nt fragment within the ORF2 gene for 333 strains in the Midi-Pyrénées and for 571 strains from the rest of France. PPR region was characterized for 56 strains. The frequency of subgenotype 3f decreased over time, whereas subgenotype 3c increased in the Midi-Pyrénées. Repartition of strains did not differ in the Midi-Pyrénées compared to the rest of France. HEV3i and HEV4 have been recently detected throughout France. PPR lengths showed that two major groups of HEV3f exist. Our study shows that HEV3 distribution in the Midi-Pyrénées was similar to the whole of France. Local dietary habits could explain the higher seroprevalence in the Midi-Pyrénées rather the circulation of a particular variant in this region.

Current Knowledge on Hepatitis E

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

Seroprevalence in blood donors reveals widespread, multi-source exposure to hepatitis E virus, southern France, October 2011

The apparent seroprevalence of hepatitis E Virus (HEV) varies greatly among developed countries depending on the geographical area and the sensitivity of immunoassays. We used a validated assay to determine the prevalence of HEV IgG and IgM antibodies among 3,353 blood donors living in southern France, who gave blood during the two first weeks of October 2011 and participated in the study. Demographic and epidemiological information was collected using a specific questionnaire. We also screened 591 samples for HEV RNA. Overall IgG seroprevalence was 39.1% and varied from 20% to 71.3% depending on the geographical area (p?<?0.001) while IgM seroprevalence was 3.31%. Anti-HEV IgG was significantly correlated with increasing age (p?<?0.001), eating uncooked pork liver sausages (p?<?0.001), offal (p?=?0.003), or mussels (p?=?0.02). Anti-HEV IgM was associated with being male (p?=?0.01) and eating uncooked pork liver sausages (p?=?0.02). HEV RNA was detected in one of the 99 anti-HEV IgM-positive samples, but in none of the 492 anti-HEV IgM-negative samples. HEV is hyperendemic in southern France. Dietary and culinary habits alone cannot explain the epidemiology of HEV in this region, indicating that other modes of contamination should be investigated.

Epidemiology of domestically acquired hepatitis E virus infection in Japan: assessment of the nationally reported surveillance data, 2007-2013

In recent years, there has been an increase in the number of reported hepatitis E virus (HEV) infections from developed countries. To describe recent trends in notification and potential risk groups and risk factors in Japan, HEV infection cases and demographic, food consumption, clinical and laboratory data reported during 2007-2013 were analysed. In total, 530 HEV infections were reported during 2007-2013. Amongst 462 domestic cases, the mean age was 56.5 years (sd 13.9) and 80.1 % were male. Forty-three cases (9.3 %) were asymptomatic, amongst which 11 were detected from blood donations. Whilst ∼50 cases were reported annually during 2007-2011, the number of reported cases increased to 121 in 2012 and 126 in 2013. The increase was characterized by a rise in the number of domestic, symptomatic cases (P = 0.05) and cases confirmed by anti-HEV IgA detection (P < 0.01). HEV genotypes G3 and G4 were consistently dominant. The major suspected source of infection was food-borne, and the major suspected foods were pig, wild boar and deer meat. The observed increase during 2012-2013 was most likely due to the coverage of the anti-HEV IgA assay by the National Health Insurance system in Japan in October 2011 and its acceptance for surveillance purposes. However, the increase was not associated with detection of asymptomatic cases. Moreover, males aged 50-69 years remained as the high-risk group, and pork and other meats continued to be the most suspected items. Our findings indicated that HEV infection is an emerging and important public health concern in Japan.

Seasonality of hepatitis: a review update

Background:

Viral hepatitis is an infection that has been reported to be present throughout the year, but some particular months are associated with higher incidences. The primary objective was to review and report on the current knowledge and evidence that existed on seasonality of different type of acute viral hepatitis worldwide in order to develop recommendations for future research, prevention and control.

Materials and Methods:

A systematic literature review was performed to identify all the primary reports and studies published during 1970-2013 on acute hepatitis A, B, C and E (AHA, AHB, AHC and AHE) in human subjects by searching PubMed, reference lists of major articles and correspondence with scientific experts. For each report or study included, the following information was extracted (as applicable to study): Location (country and setting), study population (number of cases, patients), seasonal or monthly rate and study duration.

Results:

There is no definite and consistent seasonal pattern has been observed on AHA; AHB; AHE and AHC, although evidence points towards spring and summer peak for hepatitis A, B, C and E. Multiple source of transmission such as; summer travel to an endemic area, swimming habits of the population in hot months, increase sexual contact, tattoo, poor hygiene and environmental sanitation and food habits (feco-oral transmission of viral hepatitis) probably exists and should be further investigated through analytical and epidemiological.

Hepatitis E virus: chronic infection, extra-hepatic manifestations, and treatment

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. It is an underdiagnosed disease because of the use of low-sensitivity serological assays; however, diagnostics tools, including nucleic-acid tests, have improved. HEV infection is usually an acute self-limiting disease, but causes chronic infection with rapidly progressive cirrhosis in adult and pediatric organ-transplant-patients. HEV infection evolves to chronic hepatitis in nearly 60% of HEV-infection solid-organ-transplant patients. HEV can also cause extra-hepatic manifestations, such as neurological symptoms and kidney injury. Reducing immunosuppression in transplant patients can lead to HEV clearance in one-third of patients with chronic hepatitis. The use of anti-viral therapies, such as pegylated-interferon and ribavirin, has been found to efficaciously treat HEV infection.

Serological and molecular evidence of a plausible transmission of hepatitis E virus through pooled plasma

BACKGROUND AND OBJECTIVES

Recently, hepatitis E virus has been recognized as a new transfusion-associated risk; however, its efficiency of transmission through blood products requires further investigation. Asymptomatic viremia of short duration has been observed in blood donors from several European countries to the rate of <1:10,000 and HEV transmission in recipients of blood products has been documented in Japan and Europe. Although HEV RNA was detected in large plasma fractionation pools used for manufacturing of plasma derived products, HEV transmission has not been demonstrated so far. In this study, we investigated the possibility of HEV transmission in patients with thrombotic thrombocytopenic purpura whose treatment included up to 40 l of plasma exchange.

MATERIALS AND METHODS

Thirty-six TTP patients received either solvent-detergent-treated plasma prepared by pooling of 2500 single-donor or cryosupernatant plasma. Three samples were collected from TTP patients at time 0, 1 and 6 months post-treatment and tested for anti-HEV antibodies. Patients with HEV seroconversion were also tested for viremia by PCR.

RESULTS

Two of seventeen TTP patients treated with SDP showed serological evidence of HEV infection. The 1-month samples from these patients were also positive for HEV RNA. A distinct rise of anti-HEV IgG level was detected in two other TTP patients with weak pre-existing immunity to HEV; this observation is indicative of a possible immune response boost due to a breakthrough infection.

CONCLUSION

This work provides, for the first time, indirect evidence of HEV transmission by pooled plasma and warrants further studies.

Epidemiology of zoonotic hepatitis E: a community-based surveillance study in a rural population in China

Background

Hepatitis E is caused by two viral genotype groups: human types and zoonotic types. Current understanding of the epidemiology of the zoonotic hepatitis E disease is founded largely on hospital-based studies.

Methods

The epidemiology of hepatitis E was investigated in a community-based surveillance study conducted over one year in a rural city in eastern China with a registered population of 400,162.

Results

The seroprevalence of hepatitis E in the cohort was 38%. The incidence of hepatitis E was 2.8/10,000 person-years. Totally 93.5% of the infections were attributed to genotype 4 and the rest, to genotype 1. Hepatitis E accounted for 28.4% (102/359) of the acute hepatitis cases and 68.9% (102/148) of the acute viral hepatitis cases in this area of China. The disease occurred sporadically with a higher prevalence during the cold season and in men, with the male-to-female ratio of 3∶1. Additionally, the incidence of hepatitis E increased with age. Hepatitis B virus carriers have an increased risk of contracting hepatitis E than the general population (OR = 2.5, 95%CI 1.5–4.2). Pre-existing immunity to hepatitis E lowered the risk (relative risk  = 0.34, 95% CI 0.21–0.55) and reduced the severity of the disease.

Conclusions

Hepatitis E in the rural population of China is essentially that of a zoonosis due to the genotype 4 virus, the epidemiology of which is similar to that due to the other zoonotic genotype 3 virus.

Hepatitis E: an emerging disease

Currently, the infection with the hepatitis E virus represents the most frequent cause for acute hepatitis and jaundice in the world. According to WHO estimations, around two billion people, representing one third of the world's population, live in endemic areas for HEV and, therefore, are at risk of infection. In developed countries, the circulation of the virus in both human and animal (swine, boar, deer) sewage has been confirmed; however, the incidence rate is low compared to that of developing countries where outbreaks of acute hepatitis transmitted via the fecal-oral route are originated, more frequently in the flooding season or after natural disasters, combined with deficient sanitary conditions. There are currently 4 known genotypes of HEV. Genotypes 1 and 2 are isolated in all human epidemic outbreaks in developing countries, while genotypes 3 and 4 are isolated not only in humans but also in animals, in both developing and industrialized countries. These data support genotypes 3 and 4 having zoonotic nature. The diagnosis of this disease is based in the detection of anti-HEV IgG and IgM in blood serum using enzyme-linked immunosorbent methods. However, the method that best confirms the diagnosis is the RT-PCR, which detects HEV RNA in blood serum and also provides the genotype. The clinical course is generally that of an acute hepatitis which in some cases may require hospitalization and that, in transplant patients or HIV infected individuals can become a chronic hepatitis. Furthermore, the virus constitutes an important risk for pregnant women. The hepatitis E can present a wide range of symptoms, from a subclinical case to chronic liver disease with extrahepatic manifestations. For this reason, the diagnostic is challenging if no differential diagnosis is included. There is no specific antiviral drug for hepatitis E, but satisfactory results have been observed in some patients treated with pegylated interferon alfa2a and/or ribavirin. This revision is an update of all the molecular, epidemiological, clinic and preventive knowledge on this emergent disease up to date.

Features of hepatitis E virus infection in humans and animals in Japan

In Japan, hepatitis E had long been considered to be a rare liver disease which can be accidentally imported from endemic countries in Asia and Africa, where the sanitation conditions are suboptimal. However, since the identification of the first autochthonous hepatitis E case and hepatitis E viremic domestic pigs in Japan in 2001, our understanding of hepatitis E virus (HEV) infection in this country has been changing markedly. This has largely been due to the development of serological and gene-based diagnostic assays, the accumulation of molecular epidemiological findings on HEV infection in humans and animals (as potential reservoirs for HEV in humans) and the recognition of the importance of zoonotic food-borne and other routes of transmission of HEV, including blood-borne transmission. Although it is now evident that autochthonous hepatitis E in Japan is far more common than was previously thought, clinical and subclinical HEV infections indigenous to Japan remain underdiagnosed and their prevalence is still underestimated due to the presence of unknown transmission routes and a low awareness of the infection status by many physicians in Japan. This review focuses on the features of HEV infection in humans and animals, as definitive or potential reservoirs for HEV, in Japan, and updates the current knowledge on the routes of transmission, including zoonotic routes, which are important for the maintenance and spread of HEV in Japan.

Antiviral strategies for hepatitis E virus

The hepatitis E virus is a common cause of acute hepatitis. Contrary to hepatitis B and C, hepatitis E is mostly a mild infection, although it has a high mortality in pregnant women and can evolve to chronicity in immunocompromised patients. Ribavirin and pegylated interferon-α are the only available therapies, but both have side effects that are not acceptable for prophylaxis or treatment of mild infections. In addition, these drugs cannot be used for all patient types (e.g. in case of pregnancy, specific organ transplants or co-morbidities) and in resource-poor settings. Hence there is an urgent need for better antiviral treatments that are efficacious and safe, also during pregnancy. In this review, a concise introduction to the virus and disease is provided, followed by a discussion of the available assay systems and potential molecular targets (viral proteins and host factors) for the development of inhibitors of HEV replication. Finally, directions for future research are presented.

Novel hepatitis E like virus found in Swedish moose

A novel virus was detected in a sample collected from a Swedish moose (Alces alces). The virus was suggested as a member of the Hepeviridae family, although it was found to be highly divergent from the known four genotypes (gt1–4) of hepatitis E virus (HEV). Moose are regularly hunted for consumption in the whole of Scandinavia. Thus, the finding of this virus may be important from several aspects: (a) as a new diverged HEV in a new animal species, and (b) potential unexplored HEV transmission pathways for human infections. Considering these aspects, we have started the molecular characterization of this virus. A 5.1 kb amplicon was sequenced, and corresponded to the partial ORF1, followed by complete ORF2, ORF3 and poly(A) sequence. In comparison with existing HEVs, the moose HEV genome showed a general nucleotide sequence similarity of 37–63 % and an extensively divergent putative ORF3 sequence. The junction region between the ORFs was also highly divergent; however, two putative secondary stem–loop structures were retained when compared to gt1–4, but with altered structural appearance. In the phylogenetic analysis, the moose HEV deviated and formed its own branch between the gt1–4 and other divergent animal HEVs. The characterization of this highly divergent genome provides important information regarding the diversity of HEV infecting various mammalian species. However, further studies are needed to investigate its prevalence in the moose populations and possibly in other host species, including the risk for human infection.

Protection against hepatitis E virus infection by naturally acquired and vaccine-induced immunity

Immunity acquired from infection or vaccination protects humans from symptomatic hepatitis E. However, whether the risk of hepatitis E virus (HEV) infection is reduced by the immunity remains unknown. To understand this issue, a cohort with 12 409 participants randomized to receive the hepatitis E vaccine Hecolin(®) or placebo were serologically followed up for 2 years after vaccination. About half (47%) of participants were initially seropositive. A total of 139 infection episodes, evidenced by four-fold or greater rise of anti-HEV level or positive seroconversion, occurred in participants who received three doses of treatment. Risk of infection was highest among the baseline seronegative placebo group participants (2.04%). Pre-existing immunity and vaccine-induced immunity lower the risk significantly, to 0.52% and 0.30%, respectively. In conclusion, both vaccine-induced and naturally acquired immunity can effectively protect against HEV infection.

Hepatitis E virus: foodborne, waterborne and zoonotic transmission

Hepatitis E virus (HEV) is responsible for epidemics and endemics of acute hepatitis in humans, mainly through waterborne, foodborne, and zoonotic transmission routes. HEV is a single-stranded, positive-sense RNA virus classified in the family Hepeviridae and encompasses four known Genotypes (1–4), at least two new putative genotypes of mammalian HEV, and one floating genus of avian HEV. Genotypes 1 and 2 HEVs only affect humans, while Genotypes 3 and 4 are zoonotic and responsible for sporadic and autochthonous infections in both humans and several other animal species worldwide. HEV has an ever-expanding host range and has been identified in numerous animal species. Swine serve as a reservoir species for HEV transmission to humans; however, it is likely that other animal species may also act as reservoirs. HEV poses an important public health concern with cases of the disease definitively linked to handling of infected pigs, consumption of raw and undercooked animal meats, and animal manure contamination of drinking or irrigation water. Infectious HEV has been identified in numerous sources of concern including animal feces, sewage water, inadequately-treated water, contaminated shellfish and produce, as well as animal meats. Many aspects of HEV pathogenesis, replication, and immunological responses remain unknown, as HEV is an extremely understudied but important human pathogen. This article reviews the current understanding of HEV transmission routes with emphasis on food and environmental sources and the prevalence of HEV in animal species with zoonotic potential in humans.