Prevalence of antibodies to the hepatitis E virus in pigs from countries where hepatitis E is common or is rare in the human population

Hepatitis E virus: Efficacy of pasteurization of plasma-derived VWF/FVIII concentrate determined by pig bioassay

BACKGROUND

Hepatitis E virus (HEV) is the leading cause of acute hepatitis throughout the world. Increasing blood component transfusion-associated HEV infections highlight the need for reliable virus inactivation procedures for plasma derivatives from pooled plasma donations.

STUDY DESIGN AND METHODS

An animal infection study was conducted to evaluate the efficiency of HEV inactivation by pasteurization during the manufacturing process of the von Willebrand Factor/Factor VIII (VWF/FVIII) concentrate Haemate P/Humate-P (CSL Behring, Marburg, Germany). For this purpose, groups of pigs were inoculated with stabilized VWF/FVIII intermediate spiked with HEV-positive liver homogenate and exposed to increasing incubation times of 0, 3, 6, and 10 h at 60°C. Animals were evaluated for virus replication over 27 days and in a subsequent trial over 92 days.

RESULTS

Virus replication was detected in animals up to the 6-h pasteurization group. In contrast, pasteurization for 10 h did not reveal virus detection when the observation period was 27 days. In an additional experiment using the 10-h pasteurized material, two individuals started virus excretion and seroconverted when the observation period was extended to 92 days. Based on the total infection rate (2 of 12) of the animals inoculated with the sample pasteurized for 10 h, a virus reduction factor of at least 4.7 log₁₀ is calculated.

CONCLUSION

This study demonstrates that pasteurization at 60°C for 10 h of an HEV-positive plasma derivative leads to the effective reduction of infectivity, resulting in a VWF/FVIII product with an appropriate margin of safety for HEV.

CD8+ lymphocytes but not B lymphocytes are required for protection against chronic hepatitis E virus infection in chickens

Hepatitis E is an important global disease, causing outbreaks of acute hepatitis in many developing countries and sporadic cases in industrialized countries. Hepatitis E virus (HEV) infection typically causes self-limiting acute hepatitis but can also progress to chronic disease in immunocompromised individuals. The immune response necessary for the prevention of chronic infection is T cell-dependent; however, the arm of cellular immunity responsible for this protection is not currently known. To investigate the contribution of humoral immunity in control of HEV infection and prevention of chronicity, we experimentally infected 20 wild-type (WT) and 18 immunoglobulin knockout (JH-KO) chickens with a chicken strain of HEV (avian HEV). Four weeks postinfection (wpi) with avian HEV, JH-KO chickens were unable to elicit anti-HEV antibody but had statistically significantly lower liver lesion scores than the WT chickens. At 16 wpi, viral RNA in fecal material and liver, and severe liver lesions were undetectable in both groups. To determine the role of cytotoxic lymphocytes in the prevention of chronicity, we infected 20 WT and 20 cyclosporine and CD8⁺ antibody-treated chickens with the same strain of avian HEV. The CD8 ⁺ lymphocyte-depleted, HEV-infected chickens had higher incidences of prolonged fecal viral shedding and statistically significantly higher liver lesion scores than the untreated, HEV-infected birds at 16 wpi. The results indicate that CD8 ⁺ lymphocytes are required for viral clearance and reduction of liver lesions in HEV infection while antibodies are not necessary for viral clearance but may contribute to the development of liver lesions in acute HEV infection.

Risk assessment for hepatitis E virus infection from domestic pigs introduced into an experimental animal facility in a medical school

Hepatitis E virus (HEV) is known to cause zoonotic infections from pigs, wild boars and deer. Domestic pigs have been used as an experimental animal model in medical research and training; however, the risks of HEV infection from pigs during animal experiments are largely unknown. Here, we retrospectively investigated the seroprevalence and detection rates of viral RNA in 73 domestic pigs (average 34.5 kg) introduced into an animal experimental facility in a medical school during 2012–2016. We detected anti-HEV immunoglobulin G antibodies in 24 of 73 plasma samples (32.9%), though none of the samples were positive for viral RNA. Plasma samples of 18 pigs were sequentially monitored and were classified into four patterns: sustained positive (5 pigs), sustained negative (5 pigs), conversion to positive (6 pigs) and conversion to negative (2 pigs). HEV genomes were detected in 2 of 4 liver samples from pigs that were transported from the same farm during 2016–2017. Two viral sequences of the overlapping open reading frame (ORF) 2/3 region (97 bp) were identical and phylogenetically fell into genotype 3. A 459-bp length of the ORF2 region of an amplified fragment from a pig transported in 2017 was clustered with the wbJYG1 isolate (subgenotype 3b) with 91.5% (420/459 bp) nucleotide identity. Based on our results, we suggest that domestic pigs introduced into animal facilities carry a potential risk of HEV infection to researchers, trainees and facility staff. Continuous surveillance and precautions are important to prevent HEV infection in animal facilities.

Seroprevalence of Hepatitis E Virus Infection in Pigs from Southern Bulgaria

Hepatitis E virus (HEV) has been isolated from humans and several animals' species. During the last years, the knowledge of HEV infection dramatically changed and enriched. The aim of this study was to estimate the seroprevalence of HEV in industrial pigs in different districts of Southern Bulgaria. Three hundred sixty swine serum samples were tested for anti-HEV IgG antibodies. The samples were collected from four industrial farms from three districts of Southern Bulgaria. HEV-specific antibodies in porcine serum were detected by enzyme-linked immunosorbent assay (PrioCHECK HEV Ab porcine). The overall HEV seroprevalence was 60.3%. The seropositivity varied widely depending on age groups and investigated farms. The overall prevalence in weaners was 25%, in fattening pigs 75.8%, and in group of sows was found the highest HEV positivity of 80%. The occurrence of HEV positivity in sows and fattening pigs presented odds ratio (OR) = 17.200 (95% confidence interval [CI]: 8.8-33.7) and OR = 11.342 (95% CI: 6.1-21.0), respectively, compared to weaners. The study indicated that HEV is widespread in industrial farms in Bulgaria and presented high seroprevalence in pigs. The results found that HEV seropositivity showed age dependency. The National Health Authorities should raise awareness of HEV and its zoonotic potential.

Cell culture systems for the study of hepatitis E virus

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and is the leading cause of enterically-transmitted viral hepatitis worldwide. Increasing numbers of HEV infections, together with no available specific anti-HEV treatment, contributes to the pathogen's major health burden. A robust cell culture system is required for virologic studies and the development of new antiviral drugs. Unfortunately, like other hepatitis viruses, HEV is difficult to propagate in conventional cell lines. Many different cell culture systems have been tested using various HEV strains, but viral replication usually progresses very slowly, and infection with low virion counts results in non-productive HEV replication. However, recent progress involving generation of cDNA clones and passaging primary patient isolates in distinct cell lines has improved in vitro HEV propagation. This review describes various approaches to cultivate HEV in cellular and animal models and how these systems are used to study HEV infections and evaluate anti-HEV drug candidates.

Epidemiological investigation of the novel genotype avian hepatitis E virus and co-infected immunosuppressive viruses in farms with hepatic rupture haemorrhage syndrome, recently emerged in China

Since 2016, hepatic rupture haemorrhage syndrome (HRHS) appeared in chickens of China and caused huge economic loss. To assess the infection status of the avian hepatitis E virus (HEV) and co-infected viruses, including avian leukosis virus (ALV), reticuloendotheliosis virus (REV), fowl adenovirus (FAdV), and chicken infectious anaemia virus (CIAV), in farms with HRHS, 180 liver samples were collected from 24 farms in different provinces and detected by strict molecular virology methods. Results showed that the positive rates of HEV, ALV, REV, FAdV, and CIAV were 74.44%, 20.00%, 27.78%, 31.11%, and 12.22%, respectively, whereas there are also 112 samples with co-infection, for a rate of 58%. Meanwhile, the positive rate of HEV decreased gradually with age; the lowest positive rate of ALV (5.76%) and REV (19.23%) appeared in 25-35 weeks age, during which the positive rate of CIAV was the highest (19.23%); the positive rate of HEV in layers (64.00%) was lower than that of broilers (83.33%), but the positive rates of ALV (38.46%) and CIAV (15.38%) in layers were higher than that of broilers (5.88%, 9.80%); the positive rates of HEV (75.88%) and CIAV (15.60%) in parental generation (PG) were higher than that of commodity generation (CG, 64.10%, 0.00%), whereas the positive rate of ALV showed inverse relationship (PG: 14.89%; CG: 38.46%). Additionally, phylogenetic analysis showed that all the avian HEV identified this study belong to a novel genotype, and found the close relationship between the wild strains (REV and CIAV) and corresponding isolates from contaminated vaccine. The data presented in this report will enhance the current understanding of the epidemiology characteristics in farms with HRHS in China.

Hepatitis E virus infection in swine workers: A meta-analysis

Hepatitis E virus (HEV) infects both humans and animals. Swine has been confirmed to be the principal natural reservoir, which raises a concern that HEV infection would be substantially increasing among swine workers. The present study calculated the pooled prevalence of IgG antibodies against HEV among swine workers and the general population in previous cross-sectional studies. We conducted a meta-analysis comparing the prevalence of HEV infection between swine workers and the general population, including local residents, blood donors and non-swine workers. Through searches in three databases (PubMed and OVID in English, and CNKI in Chinese) and after study selection, a total of 32 studies from 16 countries (from 1999 through 2018) were included in the meta-analysis. A random-effect model was employed in the study; an I ² statistic assessed heterogeneity, and the Egger's test detected publication bias. The comparative prevalence of anti-HEV IgG was pooled from the studies. Compared to the general population, the prevalence ratio (PR) for swine workers was estimated to be 1.52 (95% CI 1.38-1.76) with the I ² being 71%. No publication bias was detected (p = 0.40). A subgroup analysis further indicated increased prevalence of anti-HEV IgG in the swine workers in Asia (PR = 1.49, 95% CI: 1.35-1.64), in Europe (PR = 1.93, 95% CI: 1.49-2.50) and in all five swine-related occupations, including swine farmers, butchers, meat processors, pork retailers and veterinarians (PR ranged between 1.19 and 1.75). In summary, swine workers have a relatively higher prevalence of past HEV infection, and this finding is true across swine-related occupations, which confirms zoonotic transmission between swine and swine workers.

Zoonotic Hepatitis E Virus: An Ignored Risk for Public Health

Hepatitis E virus (HEV) is a quasi-enveloped, single-stranded positive-sense RNA virus. HEV belongs to the family Hepeviridae, a family comprised of highly diverse viruses originating from various species. Since confirmation of HEV's zoonosis, HEV-induced hepatitis has been a public health concern both for developing and developed countries. Meanwhile, the demonstration of a broad host range for zoonotic HEV suggests the existence of a variety of transmission routes that could lead to human infection. Moreover, anti-HEV antibody serosurveillance worldwide demonstrates a higher than expected HEV prevalence rate that conflicts with the rarity and sporadic nature of reported acute hepatitis E cases. In recent years, chronic HEV infection, HEV-related acute hepatic failure, and extrahepatic manifestations caused by HEV infection have been frequently reported. These observations suggest a significant underestimation of the number and complexity of transmission routes previously predicted to cause HEV-related disease, with special emphasis on zoonotic HEV as a public health concern. Significant research has revealed details regarding the virology and infectivity of zoonotic HEV in both humans and animals. In this review, the discovery of HEV zoonosis, recent progress in our understanding of the zoonotic HEV host range, and classification of diverse HEV or HEV-like isolates from various hosts are reviewed in a historic context. Ultimately, this review focuses on current understanding of viral pathogenesis and cross-species transmission of zoonotic HEV. Moreover, host factors and viral determinants influencing HEV host tropism are discussed to provide new insights into HEV transmission and prevalence mechanisms.

Seroepidemiology and molecular characterization of hepatitis E virus infection in swine and occupationally exposed workers in Punjab, India

Hepatitis E virus (HEV) has two discrete epidemiological patterns: waterborne epidemics in developing countries only, caused by HEV genotype I, and sporadic zoonotic outbreaks in developing and developed countries caused by genotypes III and IV. This study was designed to investigate seroprevalence, molecular detection and the characterization of HEV by nested RT-PCR in swine as well as the occupational risk to exposed human population in Punjab state of north-western India. The occupational risk-exposed group comprised of swine farmers (organized - mixed feed feeders and unorganized - swill feeders), slaughterhouse workers, sewage workers and veterinary internes. During the study period, blood and faecal samples were collected from 320 swine and 360 humans with both high and low occupational exposure risks. The overall seroprevalence of swine HEV was 65.00%, with a significantly higher seropositivity in growing pigs (2-8 months of age). The prevalence of HEV RNA in swine faecal samples by nRT-PCR was 8.75% with a significantly higher detection in swill-fed pigs. With humans in the high occupational exposure risk population, significantly higher anti-HEV IgG seropositivity was observed (60.48%) as compared to control population (10.71%). Strong evidence of association between human anti-HEV IgG seropositivity and certain occupational exposure risk groups was observed (p < 0.05). This indicates that unorganized swine farmers, slaughterhouse workers and sewage workers have higher odds of HEV infection in this study region. Percentage of nucleotide similarity between swine and human HEV isolates was less than that found in countries with zoonotic HEV outbreaks. Molecular characterization revealed the circulation of G IV and G I genotypes among swine and human population in Punjab state, respectively.

Hepatitis E: latest developments in knowledge

Hepatitis E, caused by Hepatitis E virus (HEV), is a highly prevalent disease in developing countries. In developed nations, autochthonous HEV infections seem to be an emergent disease. Its clinical manifestations and epidemiology are well known for endemic countries. It has been confirmed that hepatitis E is a zoonosis and that parenteral transmission can also occur. The molecular mechanisms of HEV replication are not fully understood, mostly because there are no efficient cell culture systems. HEV can cause chronic hepatitis in organ transplant recipients and immunocompetent patients. Cases with fulminant hepatitis and other extrahepatic manifestations have also been reported. The diagnosis is based on serological studies and detection of HEV RNA in blood and feces. Treatment with ribavirin and/or pegylated-IFN-α have proven to be successful in some cases. The recently approved/marketed vaccine is a good option in order to prevent this infection.

Hepatitis E virus as an emerging zoonotic pathogen

Hepatitis E outbreaks are a serious public health concern in developing countries. The disease causes acute infections, primarily in young adults. The mortality rate is approximately 2%; however, it can exceed 20% in pregnant women in some regions in India. The causative agent, hepatitis E virus (HEV), has been isolated from several animal species, including pigs. HEV genotypes 3 and 4 have been isolated from both humans and animals, and are recognized as zoonotic pathogens. Seroprevalence studies in animals and humans indirectly suggest that HEV infections occur worldwide. The virus is primarily transmitted to humans via undercooked animal meats in developed countries. Moreover, transfusion- and transplantation-mediated HEV infections have recently been reported. This review summarizes the general characteristics of hepatitis E, HEV infection status in animals and humans, the zoonotic transmission modes of HEV, and HEV vaccine development status.

Production and characterization of a Brazilian candidate antigen for Hepatitis E Virus genotype 3 diagnosis

Hepatitis E, caused by hepatitis E virus (HEV), is a viral infectious pathology of great importance in the public health. Hepatitis E outbreaks were registered in developing countries with poor or no sanitation, where drinking water was contaminated with fecal material, but also in many industrialized countries probably due to consumption of HEV-positive swine meat. In this study, we present the development and characterization of a recombinant antigen from ORF2 HEV genotype 3. Viral RNA was extracted from swine feces infected with the native virus. A total of 267 residues from the C-terminal ORF2((394-661)) coding sequence were cloned into the pET20a vector and expressed in Escherichia coli ER2566. Recombinant protein was purified by liquid chromatography and the fragment obtained a 98% homology against other human or swine HEV genotype 3 ORF2 sequences. Wistar rats were inoculated with ORF2p, developing antibodies able to recognize both the homologous antigen and the native HEV genotype 3 ORF2 present in infected stool. In parallel, HEV-negative swine were experimentally challenged with HEV genotype 3. ORF2 was detected by PCR 14 days post-inoculation in three-fourth piglets' feces and one week later by dot blot. In conclusion, this study proved the immunogenic and antigenic properties of the recombinant protein ORF2p.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Naturally occurring animal models of human hepatitis E virus infection

Hepatitis E virus (HEV) is a single-stranded, positive-sense RNA virus in the family Hepeviridae. Hepatitis E caused by HEV is a clinically important global disease. There are currently four well-characterized genotypes of HEV in mammalian species, although numerous novel strains of HEV likely belonging to either new genotypes or species have recently been identified from several other animal species. HEV genotypes 1 and 2 are limited to infection in humans, whereas genotypes 3 and 4 infect an expanding host range of animal species and are zoonotic to humans. Historical animal models include various species of nonhuman primates, which have been indispensable for the discovery of human HEV and for understanding its pathogenesis and course of infection. With the genetic identification and characterization of animal strains of HEV, a number of naturally occurring animal models such as swine, chicken, and rabbit have recently been developed for various aspects of HEV research, including vaccine trials, pathogenicity, cross-species infection, mechanism of virus replication, and molecular biology studies. Unfortunately, the current available animal models for HEV are still inadequate for certain aspects of HEV research. For instance, an animal model is still lacking to study the underlying mechanism of severe and fulminant hepatitis E during pregnancy. Also, an animal model that can mimic chronic HEV infection is critically needed to study the mechanism leading to chronicity in immunocompromised individuals. Genetic identification of additional novel animal strains of HEV may lead to the development of better naturally occurring animal models for HEV. This article reviews the current understanding of animal models of HEV infection in both natural and experimental infection settings and identifies key research needs and limitations.

A scoping review of the evidence for public health risks of three emerging potentially zoonotic viruses: hepatitis E virus, norovirus, and rotavirus

Emerging zoonoses are defined as those newly recognized, or increasing in incidence or geographic range. Hepatitis E virus (HEV), norovirus (NoV), and rotavirus (RV), while well known to be transmitted person-person, have also been hypothesized to be emerging zoonoses. Our objective was to investigate their potential public health risks from animal reservoirs. Given the diversity of evidence sources, a scoping review incorporating a mixed methods synthesis approach was used. A broad search was conducted in five electronic databases. Each citation was appraised independently by two reviewers using screening tools designed and tested a priori. Level 1 relevance screening excluded irrelevant citations; level 2 confirmed relevance and categorized. At level 3 screening, data were extracted to support a risk profile. A stakeholder group provided input on study tools and knowledge translation and transfer. Level 1 screening captured 2471 citations, with 1270 advancing to level 2 screening, and 1094 to level 3. We defined criteria for case attribution to zoonosis for each virus. Using these criteria, we identified a small number of zoonotic cases (HEV n=3, NoV=0, RV=40 (zoonoses=3; human-animal re-assortants=37)) categorized as 'likely'. The available evidence suggests the following potential HEV human exposure sources: swine, other domestic animals, wildlife, surface waters, and asymptomatic human shedders. Possible at-risk groups include the immunocompromised and the elderly. Reports of NoV intergenogroup recombinants suggest potential for human-animal recombination. Greatest public health impact for RV zoonoses may be the potential effect of human-animal reassortants on vaccination efficacy.

The prevalence of hepatitis E virus infections among swine, swine farmers and the general population in Guangdong Province, China

Hepatitis E virus (HEV) infection is widespread in China, but few studies have been carried out in Guangdong Province. This study aimed to characterize the prevalence of HEV infections among swine, swine farmers and the general population in Guangdong Province. We conducted an epidemiological study that included swine, swine farmers and health examination attendees in Guangdong from 2011 to 2013. The overall seroprevalence of anti-HEV antibodies in swine was 64.7%. The results revealed that growing pigs, sows and boars (OR ranges from 3.5 to 21.5) have a higher risk than nursery pigs. HEV RNA in swine bile showed that HEV is epidemic in swine in the Pearl River Delta, with the highest prevalence of 22.73% in Foshan. Some genomes of HEV strains from each district were sequenced. Phylogenetic analysis of partial open reading frame 2 (ORF2) shows that they belong to genotype IV and are most closely related to isolates from China. In total, 307 participants were enrolled in the study, including 114 swine farmers and 193 attendees from hospitals. IgG anti-HEV was detected in 48.25% of swine farmers and in 38.34% of the general population. Seroprevalence rates were almost stratified by age, with a higher positive rate for males compared to females across all age groups. Women on swine farms appeared to have a lower risk of infection compared to the general population, revealing that the risk factors for HEV infection are not unique. The results suggested that there were other risk factors for HEV infection. HEV infection is prevalent in Guangdong, but due to the small sample sizes, more investigations are needed to assess the potential impact of HEV infection, and many additional risk factors should be considered.

Hepatitis E virus infections in humans and animals

Hepatitis E has traditionally been considered an endemic disease of developing countries. It generally spreads through contaminated water. However, seroprevalence studies have shown that hepatitis E virus (HEV) infections are not uncommon in industrialized countries. In addition, the number of autochthonous hepatitis E cases in these countries is increasing. Most HEV infections in developed countries can be traced to the ingestion of contaminated raw or undercooked pork meat or sausages. Several animal species, including pigs, are known reservoirs of HEV that transmit the virus to humans. HEVs are now recognized as an emerging zoonotic agent. In this review, we describe the general characteristics of HEVs isolated from humans and animals, the risk factors for human HEV infection, and the current status of human vaccine development.

Detection and characterisation of hepatitis E virus in naturally infected swine in Croatia

Hepatitis E is a viral zoonotic disease infecting swine worldwide. Since pigs represent a likely animal reservoir for the hepatitis E virus, the epidemiology of naturally occurring hepatitis E was investigated in Croatian swine herds. Nearly all tested animals were seropositive for antibodies against the hepatitis E virus (55/60, 91.7%). Active infection was detected in all age groups by RT-PCR of viral RNA in serum (8/60, 13.3%) and bile samples (3/37, 8.1%), which was further confirmed by histopathological findings of characteristic lesions in the livers of the infected animals. Three new strains of hepatitis E virus were isolated from Croatian pig herds. Phylogenetic analysis using median-joining networks clustered those Croatian strains with isolates from various parts of the world, indicating their likely origin in international trade. Similarity to human isolates implies a zoonotic potential of Croatian strains, which raises a public health concern, especially in the light of the high prevalence of hepatitis E in the herds studied.

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.

A cross-sectional study of hepatitis E virus infection in pigs in different-sized farms in northern Thailand

Pigs are an important reservoir of hepatitis E virus (HEV) in many countries throughout the world. We evaluated the association between farm size and presence of serum antibodies against HEV, as well as other risk factors for infection in pigs raised in Nan Province, Thailand in a cross-sectional study. The sampling frame was a total-population census of all pig herds, stratified into three classes of the farm size according to criteria developed by the Nan provincial livestock health office. One-eighth of all pigs in each farm were sampled randomly. All pig-farm owners were interviewed to elicit information on general characteristics of their farms, biosecurity and hygienic procedures, and farm management. We obtained sera and fecal samples from 879 pigs to test for antibodies to HEV and HEV RNA. Odds ratios (OR) and 95% confidence intervals (CI) for risk factors for HEV seroprevalence were estimated by multivariate logistic regression. The overall prevalence of anti-HEV immunoglobulin G antibodies was 9.9%. Pigs studied from medium-sized farms had a higher HEV seroprevalence than those from larger farms (adjusted OR 4.95, 95% CI: 1.79, 13.70). Factors associated with HEV seropositivity included feeding pigs with agro-industrial byproducts, having veterinarians on farms, and presence of other pig farms within 100 m. Twenty-five (2.9%) of 875 sampled pig stools were positive for HEV RNA. Phylogenetic analysis revealed that all HEV isolates clustered to HEV genotype 3.

A cross-sectional study of hepatitis E virus infection in healthy people directly exposed and unexposed to pigs in a rural community in northern Thailand

A cross-sectional study of the association between occupational pig exposure and hepatitis E virus (HEV) infection in adult pig farmers and the general population who were not directly exposed to pigs was conducted in Nan Province, Thailand, from November 2010 to April 2011. All participants were interviewed to provide information on their job history, eating habits and other potential confounders. The prevalence of anti-HEV immunoglobulin G antibodies (IgG) among 513 subjects was 23.0%. Hand washing with water and soap was associated with a lower seroprevalence of HEV infection, whereas living in an area with frequent flooding (OR 1.64, 95% CI: 1.00-2.68) and consuming internal pig organs more than twice per week (OR 3.23, 95%CI: 1.15-9.01) were both associated with a higher seroprevalence of anti-HEV IgG. There was no association between HEV seroprevalence and frequent, direct occupational pig contact.

Hepatitis E virus genotype 3 in wild rats, United States

The role of rodents in the epidemiology of zoonotic hepatitis E virus (HEV) infection has been a subject of considerable debate. Seroprevalence studies suggest widespread HEV infection in commensal Rattus spp. rats, but experimental transmission has been largely unsuccessful and recovery of zoonotic genotype 3 HEV RNA from wild Rattus spp. rats has never been confirmed. We surveyed R. rattus and R. norvegicus rats from across the United States and several international populations by using a hemi-nested reverse transcription PCR approach. We isolated HEV RNA in liver tissues from 35 of 446 rats examined. All but 1 of these isolates was relegated to the zoonotic HEV genotype 3, and the remaining sequence represented the recently discovered rat genotype from the United States and Germany. HEV-positive rats were detected in urban and remote localities. Genetic analyses suggest all HEV genotype 3 isolates obtained from wild Rattus spp. rats were closely related.

Bats worldwide carry hepatitis E virus-related viruses that form a putative novel genus within the family Hepeviridae

Hepatitis E virus (HEV) is one of the most common causes of acute hepatitis in tropical and temperate climates. Tropical genotypes 1 and 2 are associated with food-borne and waterborne transmission. Zoonotic reservoirs (mainly pigs, wild boar, and deer) are considered for genotypes 3 and 4, which exist in temperate climates. In view of the association of several zoonotic viruses with bats, we analyzed 3,869 bat specimens from 85 different species and from five continents for hepevirus RNA. HEVs were detected in African, Central American, and European bats, forming a novel phylogenetic clade in the family Hepeviridae. Bat hepeviruses were highly diversified and comparable to human HEV in sequence variation. No evidence for the transmission of bat hepeviruses to humans was found in over 90,000 human blood donations and individual patient sera. Full-genome analysis of one representative virus confirmed formal classification within the family Hepeviridae. Sequence- and distance-based taxonomic evaluations suggested that bat hepeviruses constitute a distinct genus within the family Hepeviridae and that at least three other genera comprising human, rodent, and avian hepeviruses can be designated. This may imply that hepeviruses invaded mammalian hosts nonrecently and underwent speciation according to their host restrictions. Human HEV-related viruses in farmed and peridomestic animals might represent secondary acquisitions of human viruses, rather than animal precursors causally involved in the evolution of human HEV.

Detection and characterization of hepatitis E virus in domestic pigs of different ages in Portugal

This study represents the primary hepatitis E virus (HEV) surveillance in domestic pigs in Portugal, five pig farms were investigated in 5 different Portuguese regions, ten faecal samples were collected at four different stages of the production. All faecal samples were tested for hepatitis E virus by real-time RT-PCR. At least one sample from each farms of all age groups tested positive for HEV. The prevalence in the pig herds varied from 10% to 30% and the mean prevalence was 32% in weaners, 20% in growers, 32% in fatteners and 4% in adult dry sows. Phylogenetic analysis of the detected HEV sequences indicated that the circulating virus strains belong under the genotype 3.

Hepatitis E virus in rats, Los Angeles, California, USA

This virus is unlikely to be a zoonotic threat.

The role of rats in human hepatitis E virus (HEV) infections remains controversial. A genetically distinct HEV was recently isolated from rats in Germany, and its genome was sequenced. We have isolated a genetically similar HEV from urban rats in Los Angeles, California, USA, and characterized its ability to infect laboratory rats and nonhuman primates. Two strains of HEV were isolated from serum samples of 134 wild rats that had a seroprevalence of antibodies against HEV of ≈80%. Virus was transmissible to seronegative Sprague-Dawley rats, but transmission was spotty and magnitude and duration of infection were not robust. Viremia was higher in nude rats. Serologic analysis and reverse transcription PCR were comparably sensitive in detecting infection. The sequence of the Los Angeles virus was virtually identical to that of isolates from Germany. Rat HEV was not transmissible to rhesus monkeys, suggesting that it is not a source of human infection.

Hepatitis E virus in Norway rats (Rattus norvegicus) captured around a pig farm

Background

Hepatitis E virus (HEV) transmitted via the oral route through the consumption of contaminated water or uncooked or undercooked contaminated meat has been implicated in major outbreaks. Rats may play a critical role in HEV outbreaks, considering their negative effects on environmental hygiene and food sanitation. Although the serological evidence of HEV infection in wild rodents has been reported worldwide, the infectivity and propagation of HEV in wild rats remain unknown. To investigate if rats are a possible carrier of HEV, we studied wild Norway rats (Rattus norvegicus) that were caught near a pig farm, where HEV was prevalent among the pigs.

Methods

We examined 56 Norway rats for HEV. RNA from internal organs was examined for RT-PCR and positive samples were sequenced. Positive tissue samples were incubated with A549 cell line to isolate HEV. Anti-HEV antibodies were detected by ELISA.

Results

Sixteen rats were seropositive, and the HEV RNA was detected in 10 of the 56 rats. Sequencing of the partial ORF1 gene from 7 samples resulted in partially sequenced HEV, belonging to genotype 3, which was genetically identical to the HEV prevalent in the swine from the source farm. The infectious HEVs were isolated from the Norway rats by using the human A549 cell line.

Conclusions

There was a relatively high prevalence (17.9%) of the HEV genome in wild Norway rats. The virus was mainly detected in the liver and spleen. The results indicate that these animals might be possible carrier of swine HEV in endemic regions. The HEV contamination risk due to rats needs to be examined in human habitats.

Role of hepatitis E infection in acute on chronic liver failure in Egyptian patients

BACKGROUND

The vast majority of patients who are referred to a specialist hepatological centre suffer from acute deterioration of their chronic liver disease. Yet, this entity of acute on chronic liver failure remains poorly defined.

AIM

The aim of the present study was to highlight the occurrence of hepatitis E viraemia by nested reverse transcriptase polymerase chain reaction (RT-PCR) in patients with acute on chronic liver failure.

MATERIALS AND METHODS

The study included 100 patients with acute on chronic liver disorders admitted to Mansoura University Hospital, Egypt. Blood samples were obtained from patients and sera were separated. Sera were subjected to a study of viral hepatitis markers for hepatitis A by IgM, for hepatitis B by S antigen and core IgM and for hepatitis C virus by IgG and RT-PCR for HCV. Liver function tests were evaluated including alanine transaminase, aspartate transaminase and bilirubin total and direct by an autoanalyser. Study for hepatitis E virus (HEV) was performed using a molecular technique. Nested RT-PCR was performed for each serum sample.

RESULTS

HEV RNA was detected in the sera of 13 patients (13%) of the patients with chronic liver disorders. The majority of the positive cases were among patients with cirrhosis (29.9%) followed by patients with HCC (15.4%). On multirisk analysis for the factors associated with the presence of HEV viraemia, younger age < 45 years and lower albumin level < 3.5 g/dl were significantly (P = 0.04, P = 0.03) associated with HEV viraemia.

DISCUSSION

From this study it appears that HEV viraemia is a common cause of acute on chronic liver disorders in Egypt.

CONCLUSION

There is no effective vaccine is available against HEV, mass awareness and preventive measures are important to the related.

Hepatitis E virus infection in developed countries

Hepatitis E was considered to be endemic infectious disease in developing countries in tropical or subtropical regions with poor sanitary conditions. Large, previously reported outbreaks were mainly due to contaminated water or heavy flooding. Prototype hepatitis E viruses of genotypes I and II were obtained from such endemic cases. In developed countries, in contrast, hepatitis E was rare and diagnosed only in travelers or imported cases. However, the development of accurate diagnostic tests, mainly PCR detection elucidated that autochthonous hepatitis E in developed countries is far more common than previously thought. Although the main route of transmission is food-borne, other routes including blood-borne have been suggested. Recent developments of gene-based diagnostic assays and molecular epidemiology have disclosed the significance of hepatitis E virus infection in developed countries.

Clinical characteristics of hepatitis E in a "Non-Endemic" population

Hepatitis E virus (HEV) is a ribonucleic acid (RNA) virus with predominant fecal oral spread. Traditionally in Western Europe it is associated with travel to endemic countries, but an increasing number of locally acquired cases have been reported throughout England. Patients presenting with acute non-travel associated HEV infection in south Wales over a 25-month period were monitored, in an attempt to understand the clinical picture and epidemiology in our patient population. Twenty-four patients were identified with non-travel associated HEV infection and studied prospectively. Patient demographics, symptoms, and serial laboratory results were recorded. There was a male/female ratio of 3:1, with a median patient age of 65.5 years old. Patients developed a significant icteric hepatitis (median peak bilirubin: 139 µmol/L, median peak AST: 1,973 IU/L and ALT: 2,021 IU/L), with liver function remaining abnormal for ∼7 weeks. All patients in whom HEV RNA was isolated were infected with genotype 3. Forty-six percent of patients presented during winter months. The data show a group mortality rate of 4.2%, similar to that reported in endemic countries. HEV results in a severe and occasionally fatal hepatitis. Testing for hepatitis E is now recommended in any patient presenting with acute hepatitis of unknown etiology.

Zoonotic hepatitis E: animal reservoirs and emerging risks

Hepatitis E virus (HEV) is responsible for enterically-transmitted acute hepatitis in humans with two distinct epidemiological patterns. In endemic regions, large waterborne epidemics with thousands of people affected have been observed, and, in contrast, in non-endemic regions, sporadic cases have been described. Although contaminated water has been well documented as the source of infection in endemic regions, the modes of transmission in non-endemic regions are much less known. HEV is a single-strand, positive-sense RNA virus which is classified in the Hepeviridae family with at least four known main genotypes (1–4) of mammalian HEV and one avian HEV. HEV is unique among the known hepatitis viruses, in which it has an animal reservoir. In contrast to humans, swine and other mammalian animal species infected by HEV generally remain asymptomatic, whereas chickens infected by avian HEV may develop a disease known as Hepatitis-Splenomegaly syndrome. HEV genotypes 1 and 2 are found exclusively in humans while genotypes 3 and 4 are found both in humans and other mammals. Several lines of evidence indicate that, in some cases involving HEV genotypes 3 and 4, animal to human transmissions occur. Furthermore, individuals with direct contact with animals are at higher risk of HEV infection. Cross-species infections with HEV genotypes 3 and 4 have been demonstrated experimentally. However, not all sources of human infections have been identified thus far and in many cases, the origin of HEV infection in humans remains unknown.

Long-term shedding of hepatitis E virus in the feces of pigs infected naturally, born to sows with and without maternal antibodies

Pigs are presumed reservoirs for hepatitis E virus (HEV) transmission to humans. To examine infection kinetics, two litters of domestic pigs (A and B, each containing 10 piglets) infected naturally with HEV were studied until pigs were 6 months old. Maternal IgG and IgA antibodies were detected in litter A piglets, but not in litter B ones. All pigs shed HEV in feces when they were 30-110 days old, and 17 developed viremia at 40-100 days of age. Phylogenetic analysis revealed a highly close sequence of HEV genotype 3 in all pigs. The serum levels of specific IgG and IgA were similar in all pigs, although IgA was not detected in the feces. Interestingly, the onset of both viremia and seroconversion was delayed significantly in litter A pigs. The kinetics of fecal virus shedding was similar in both litters; shedding was not detected after the pigs were 120 days old. The differences in the infection kinetics between litters A and B suggested that maternal antibodies delayed the onset of viremia and seroconversion. Quantitative real-time reverse transcriptase-polymerase chain reaction revealed that HEV RNA in feces peaked 10 days after initial shedding of approximately 10(6.0) copies/g. The viral load was much lower in the serum than in the feces. At 200 days of age, HEV RNA was found in the internal organs of 3 out of 13 pigs. These study findings improve the understanding of the dynamics of natural HEV transmission in pigs, which could help in controlling virus transmission from pigs to humans.

National mortality rates from chronic liver disease and consumption of alcohol and pig meat

A correlation between national pig-meat consumption and mortality rates from chronic liver disease (CLD) across developed countries was reported in 1985. One possible mechanism explaining this may be hepatitis E infection spread via pig meat. We aimed to re-examine the original association in more recent international data. Regression models were used to estimate associations between national pig-meat consumption and CLD mortality, adjusting for confounders. Data on CLD mortality, alcohol consumption, hepatitis B virus (HBV) and hepatitis C virus (HCV) seroprevalence for 18 developed countries (1990-2000) were obtained from WHO databases. Data on national pig-meat and beef consumption were obtained from the UN database. Univariate regression showed that alcohol and pig-meat consumption were associated with mortality from CLD, but beef consumption, HBV and HCV seroprevalence were not. A 1 litre per capita increase in alcohol consumption was associated with an increase in mortality from CLD in excess of 1.6 deaths/100,000 population. A 10 kg higher national annual average per capita consumption of pork meat was associated with an increase in mortality from CLD of between 4 and 5 deaths/100,000 population. Multivariate regression showed that alcohol, pig-meat consumption and HBV seroprevalence were independently associated with mortality from CLD, but HCV seroprevalence was not. Pig-meat consumption remained independently associated with mortality from CLD in developed countries in the 1990-2000 period. Further work is needed to establish the mechanism.

Hepatitis E virus antibodies in patients with chronic liver disease

In the United States, the seroprevalence rate for hepatitis E virus (HEV) is ≈20%. This study examined HEV seroprevalence in persons with and without chronic liver disease. Our data indicate that HEV seropositivity is high in patients with chronic liver disease and that HEV seroprevalence increases significantly with age.

Mice are not susceptible to hepatitis E virus infection

To determine whether or not mice are susceptible to hepatitis E virus (HEV) infection, C57BL/6 mice were experimentally infected with genotypes 1, 3 and 4 HEV by intravenous injection. Serum and stool samples were collected and used to detect HEV RNA and anti-HEV antibodies by RT-PCR and ELISA. The virus infection was monitored up to two months after inoculation; however, none of the serum or stool samples was positive for virus replication, demonstrating that C57BL/6 mice were not susceptible to HEV.

Full-length sequence of genotype 3 hepatitis E virus derived from a pig in Thailand

Hepatitis E virus (HEV) infection in pigs was investigated in two principal swine farming areas in Thailand. Anti-HEV antibodies and HEV RNA in sera were examined in 258 pigs reared on five commercial farms from age 1 to 6.5 months and sows. Overall, 167 of 258 (64.7%) pigs were positive for anti-HEV IgG, while 20 of 258 (7.75%) had detectable HEV RNA. Sequence analysis of 20 HEV isolates obtained from viremic pigs revealed that they were 92.3-100% identical to each other and had 82.2-88.2% nucleotide similarity to other reported genotype 3 isolates in 415 nucleotide sequences within ORF2 region. Further characterization by sequencing the complete genome of the Thai swine HEV isolate (named Thai-swHEV07) and phylogenetic analysis showed that Thai-swHEV07 segregated into a cluster consisting of swine isolates from Japan, Mongolia, and Kyrgyzstan within the HEV genotype 3. The Thai-swHEV07 had a genomic length of 7,229 nt excluding the polyadenylated region at 3' terminus of the genome. Comparison of Thai-swHEV07 and 27 reported strains of genotype 3 revealed 80.4-85.9% nucleotide identity, with the highest identity of 85.9% to the novel swHEV strain from Mongolia. These findings suggest that genotype 3 HEV isolates are markedly heterogeneous.

Indigenous hepatitis E virus infection in England: more common than it seems

BACKGROUND

Indigenous hepatitis E virus (HEV) is increasingly diagnosed in England due to a better awareness and understanding of the virus. However, the true burden of infection and therefore its implication to public health remains undefined.

OBJECTIVES

To estimate the HEV seroprevalence in the general population and to investigate how the risk of HEV infection had fluctuated over time.

STUDY DESIGN

Two sample collections stratified by age ranging from 1 to 80 years, were screened for HEV IgG antibody. The two collections were separated by 13 years enabling the average incidence between 1991 and 2004 to be estimated. Additional force of infection calculations were also undertaken.

RESULTS

An overall HEV antibody prevalence of 13% was determined, increasing with age and peaking at 25% in those aged over 50 years. Analysis of the two sample collections demonstrated a temporal shift in seroprevalence indicating that the risk of acquiring HEV infection was not solely age dependant. Data showed that the force of infection had been particularly high in the middle of the 20th century but had subsequently decreased. Current HEV incidence estimates revealed that the incidence did not vary in different age groups.

CONCLUSIONS

This study indicated a high anti-HEV seroprevalence in England and that there was a period of increased risk of acquiring HEV infection which has now decreased. Incidence estimates show that shared risk factors still exist for acquiring HEV infection across all age groups in England.

Comparative analysis of different TaqMan real-time RT-PCR assays for the detection of swine Hepatitis E virus and integration of Feline calicivirus as internal control

AIMS

The aim of this study was to compare the performance of four TaqMan RT-PCR assays with a commonly used nested RT-PCR and to include the Feline calicivirus (FCV) as an internal control.

METHODS AND RESULTS

RNA extracted from 87 swine faecal samples and 103 swine blood samples was subjected to different detection systems. Faecal samples naturally contaminated with Hepatitis E virus (HEV) and negative samples were artificially inoculated with 3.2 x 10(3) PFU of FCV. Detection results obtained on faecal and plasma samples were 35.6% and 4.9% with the nested RT-PCR assay, 8.0% and 0%, 0% and 0%, 13.8% and 0% and 36.8% and 3.9% with TaqMan systems A, B, C and D respectively. The Ct means obtained with the multiplex TaqMan assay were 30.11 and 30.43 for the detection of FCV with HEV contaminated samples and negative samples.

CONCLUSIONS

The TaqMan system D was more suitable for the detection of swine HEV strains than the three others and FCV was integrated successfully as an internal control.

SIGNIFICANCE AND IMPACT OF THE STUDY

FCV was demonstrated as an efficient control to monitor the RNA extraction process and HEV amplification procedure in a multiplex HEV/FCV TaqMan assay. This control would be helpful in limiting false negative results.

Excretion of hepatitis E virus by pigs of different ages and its presence in slurry stores in the United Kingdom

Five faecal samples were collected from four different stages of production at each of 10 pig farms in the Yorkshire Humberside area of the UK, and samples of slurry were collected from nine of the farms. All the samples were tested for hepatitis E virus (HEV) RNA by a nested reverse transcriptase PCR. At least one sample from the pigs on each of the farms tested positive for hev; its prevalence in the 10 herds varied from 5 per cent to 35 per cent and its mean prevalence was 21.5 per cent. The mean prevalence in pigs aged three to five weeks was 26.0 per cent, in pigs aged 10 to 12 weeks 44.0 per cent, in pigs aged 22 to 24 weeks 8.9 per cent, and in adult dry sows 6.0 per cent. Two of the nine slurry lagoons tested positive for HEV RNA. Phylogenetic analysis of the sequence data indicated that the strains of the virus were of genotype 3 and closely related to strains detected in other pigs and in human beings in the UK.

Time trend of the prevalence of hepatitis E antibodies among farmers and blood donors: a potential zoonosis in Denmark

BACKGROUND

Antibody to hepatitis E virus (anti-HEV) is prevalent in Western countries, where clinical hepatitis E is rarely reported. The aim of this study was to determine the prevalence of anti-HEV among Danish blood donors and Danish farmers. In addition, we compared the prevalence among 2 sets of serum samples obtained from blood donors 20 years apart.

METHODS

Samples from 291 Danish farmers and 169 blood donors that were collected in 1983 and samples from 461 blood donors that were collected in 2003 were tested for anti-HEV. Relevant information on HEV exposure was collected by self-administered questionnaire.

RESULTS

Anti-HEV testing was performed on samples after 20 years of storage at -20 degrees C. The prevalence of anti-HEV was 50.4% among farmers and 32.9% among donors in 1983 and 20.6% among donors in 2003 (P < .05). Presence of anti-HEV was significantly correlated with increasing age in all 3 groups (P < .05). Among donors who had serum samples obtained in 2003, age, contact with horses, and the presence of antibody to hepatitis A virus were associated with the presence of anti-HEV in multivariate analysis. Among farmers, only age was independently associated with the presence of anti-HEV.

CONCLUSION

Anti-HEV was highly prevalent among Danes but has decreased in prevalence over the past 50 years. Our study supports the hypothesis that HEV infection in Denmark may be an asymptomatic zoonotic infection.

Retrospective serological study on hepatitis E infection in pigs from 1985 to 1997 in Spain

The objective of the present work was to ascertain the date in which hepatitis E virus (HEV) was introduced in the Spanish pig population. For this, a serological retrospective study was carried out using archived sera. A total of 2871 serum samples gathered between 1985 and 1997 and collected in 208 farms of Spain were tested for anti-HEV IgG by an in-house ELISA. Of the 2871 sera analyzed by ELISA, 1390 were positive for anti-HEV antibodies (48.4%, 95% CI: 46.9-49.9%) and that corresponded to 204/208 farms (98%, 95% CI: 96.1-99.9%) having at least one positive pig. Our results show that HEV was present and widespread in Spanish swine farms at least since 1985. Any significant changes in prevalence were detected from 1 year to another and therefore, HEV infection in swine should be considered endemic in Spain.

Hepatitis e: a UK perspective

Hepatitis E is increasingly recognized as a cause of viral hepatitis within the UK and should be considered in any patient presenting with acute hepatitis. Mortality rates of around 4% have been described, but are even higher during pregnancy.

Investigation of hepatitis E virus infection in swine from Hunan province, China

Nine hundred and four serum samples were collected from pigs from 16 pig farms in China's Hunan province and tested for anti-hepatitis E virus (HEV) antibody and the HEV capsid antigen using EIAs. Of the 904 samples, 617 (68.3%) and 57 (6.3%) were positive for anti-HEV antibody and antigen, respectively. The prevalence of HEV antibodies and detection of antigen varied significantly among pigs from different farms (P < 0.01). The positivity rate for anti-HEV antibody and occurrence of high titer antibody were significantly higher in pigs above, than in those below, 3 months of age, whilst the detection of antigen did not differ significantly between the two groups. Based on these data, 481 serum samples that were positive for HEV antigen or with an S/CO < or =10 for anti-HEV were tested for HEV RNA using real-time RT-PCR; 28 of 481 (5.8%) were positive. The positivity rate of HEV RNA was much higher for the HEV antigen positive sera (40.1%) than the anti-HEV antibody positive (1.4%) or negative (1.1%), antigen negative samples. Sixteen of the 28 samples were positive for HEV RNA using nested RT-PCR and their products were cloned and sequenced. These 16 isolates belonged to HEV genotype 4, including 12 that did not belong to any subtype of HEV genotype 4 reported previously. Thus, the infection rate of HEV in pigs is high and the HEV antigen has a close relationship with HEV RNA. The HEV genotype infecting the pigs was genotype 4 and a novel subtype may exist in Hunan province.

The detection and characterization of hepatitis E virus in pig livers from retail markets of India

The zoonotic transmission of Hepatitis E virus (HEV) is a well-established fact and pigs are known reservoirs of the virus. The human and swine HEV from countries such as the USA, Japan and Taiwan, show a remarkable sequence identity. Swine liver samples from markets in Japan and US were shown to be HEV RNA positive. In contrast, in India, viruses belonging to different genotypes, that is, genotypes 1 and 4 circulate in humans and pigs respectively, at least for the last 20 years. To assess possible exposure of the Indian population to swine HEV, 240 pig liver samples were collected from retail markets of Pune, western India. Two (0.83%) samples were found positive for HEV RNA by nested RT-PCR. Nucleotide sequence-based phylogenetic analysis showed the presence of genotype 4 HEV with 90-91% similarity and clustering with Indian swine HEV sequences generated earlier. The data suggest the possibility of HEV infection in persons consuming infected pig liver. So far, it has not been possible to detect any type 4 HEV infection in humans. The absence of type 4 infections in humans may be attributed to cooking leading to the inactivation of the virus.

Autochthonous hepatitis E in Southwest England: natural history, complications and seasonal variation, and hepatitis E virus IgG seroprevalence in blood donors, the elderly and patients with chronic liver disease

AIMS

To report the natural history of autochthonous hepatitis E and hepatitis E virus (HEV) IgG seroprevalence in Southwest England.

METHODS

Patients with unexplained hepatitis were tested for hepatitis E and cases followed until recovery or death. Five hundred blood donors, 336 individuals over the age of 60 years and 126 patients with chronic liver disease were tested for HEV IgG.

RESULTS

Forty cases of autochthonous hepatitis E (genotype 3) were identified. Hepatitis E was anicteric in 25% of cases and usually caused a self-limiting hepatitis predominantly in elderly Caucasian males. Six of 40 had a significant complication and three patients died, two of who had previously undiagnosed cirrhosis. Hepatitis E shows a seasonal variation with peaks in the spring and summer and no cases in November and December. HEV IgG prevalence increases with age, is more common in men and is 16% in blood donors, 13% in patients with chronic liver disease and 25% in individuals over 60 years.

CONCLUSION

Autochthonous hepatitis E is more common than previously recognized, and should be considered in the differential diagnosis in patients with hepatitis, whatever their age or travel history. It carries a significant morbidity and when seen in the context of chronic liver disease carries an adverse prognosis.

Hepatitis E autochthonous infection in chronic liver disease

Hepatitis E virus is endemic in many parts of the developing world and causes a self-limiting hepatitis in young adults, except in pregnant women and patients with chronic liver disease, where the mortality is high. Locally acquired hepatitis E is increasingly recognized in the developed world. It is caused by hepatitis E virus genotype 3, affects the middle-aged and the elderly, and may be a zoonotic infection from pigs. We present a case of locally acquired hepatitis E infection in a patient with previously undiagnosed cirrhosis, which resulted in subacute liver failure and death. We describe our attempt to trace this infection to a free-range pig farm adjacent to the patient's place of employment. Hepatitis E infection should be considered in the differential diagnosis in patients with decompensated chronic liver disease whatever their age or travel history. When found, the prognosis may be poor.

Prevalence of hepatitis E virus in swine under different breeding environment and abattoir in Beijing, China

This study was to investigate the prevalence of HEV in pig herds under different breeding environment and in abattoirs located in Beijing, China. In total 638 sera samples and 114 liver samples were collected for a serological survey and a RT-PCR assay, respectively. The average prevalence rate of HEV in pig herds in Beijing suburb were 47.5-100%. Seropositive rate was 76.6% for pig herds of large-scale and 90% for family-scale farms. For sera samples collected from abattoir, 127 samples (78.4%) were found to be positive. Among four liver samples (3.5%) that positive for HEV RNA detection, two strains of HEV has been identified. the two detected HEV sequences shared 99.1% nucleotide sequence identity with each other, and 76.4-81.0%, 76.5-76.8%, 75.7-79.0% and 85.2-96.4% with related strains representing genotype 1, 2, 3, and 4, respectively. Further phylogenetic analysis revealed two HEV sequences belonged to genotype 4 and exhibited a high identity with strain JKO-ChiSai98C (95.4 and 95.7%), and with strains 87, 277 and 292 (96.1-96.4%) isolated from patients with sporadic acute hepatitis E in Beijing, China. The results of this study indicated that the prevalence of HEV in the pig herds were quite high. Additional public-health concerns might be placed on pork safety.

Hepatitis E virus infection dynamics and organic distribution in naturally infected pigs in a farrow-to-finish farm

The objective of the present study was to determine the pattern of Hepatitis E virus (HEV) infection in a naturally infected, farrow-to-finish herd. For that purpose, a prospective study was conducted in randomly selected 19 sows and 45 piglets. Blood samples were collected from sows at 1 week post-farrowing and from piglets at 1, 3, 6, 9, 12, 15, 18 and 22 weeks of age. Furthermore 3 or 5 animals were necropsied at each bleeding day (but at 1 week of age), and serum, bile, liver, mesenteric lymph nodes and faeces taken. HEV IgG, IgM and IgA antibodies were determined in serum and viral RNA was analysed in all collected samples by semi-nested RT-PCR. Histopathological examination of mesenteric lymph nodes and liver was also conducted. From 13 analysed sows, 10 (76.9%) were positive to IgG, one to IgA (7.7%) and two to IgM (15.4%) antibodies specific to HEV. In piglets, IgG and IgA maternal antibodies lasted until 9 and 3 weeks of age, respectively. IgG seroconversion occurred by 15 weeks of age while IgM and IgA at 12. On individual basis, IgG was detectable until the end of the study while IgM and IgA antibody duration was of 4-7 weeks. HEV RNA was detected in serum at all analysed ages with the highest prevalence at 15 weeks of age. HEV was detected in faeces and lymph nodes for the first time at 9 weeks of age and peaked at 12 and 15 weeks of age. This peak coincided with the occurrence of hepatitis as well as with HEV detection in bile, liver, mesenteric lymph nodes and faeces, and also with highest IgG and IgM OD values at 15 weeks. Finally, different HEV sequences from this farm were obtained, which they clustered within 3 different groups, together with other Spanish sequences, all of them of genotype 3. Moreover, the present study also indicates that the same pig can be infected with at least two different strains of HEV during its productive life. This is the first study characterizing HEV infection in naturally infected pigs with chronological virus detection and its relationship with tissue lesions throughout the productive life of the animals.