Hepatitis E Virus in Wild Boars and Spillover Infection in Red and Roe Deer, Germany, 2013-2015

Trends and Challenges in the Detection and Environmental Surveillance of the Hepatitis E Virus

The Hepatitis E virus (HEV) is responsible for causing Hepatitis E, a zoonotic disease that has emerged as a significant global health concern, accounting for about 20 million infections and 70,000 deaths annually. Although it is often recognized as a disease that is acute in low-income countries, HEV has also been recognized as a zoonotic disease in high-income countries. The zoonotic transmission requires flexible approaches to effectively monitor the virus, vectors, and reservoirs. However, the environmental monitoring of HEV presents additional challenges due to limitations in current detection methods, making it difficult to accurately assess the global prevalence of the virus. These challenges hinder efforts to fully understand the scope of the disease and to implement effective control measures. This review will explore these and other critical concerns, addressing gaps in HEV research and highlighting the need for improved strategies in the monitoring, prevention, and management of Hepatitis E using a One Health approach.

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

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

Large-scale HEV genotype 3 outbreak on New Caledonia Island

BACKGROUND AND AIMS

Several symptomatic cases of HEV infections were reported to the New Caledonia Island Public Health Service between August and December 2023. This prompted epidemiological and virological investigations to identify the source of infection.

APPROACH AND RESULTS

HEV RNA was assessed in symptomatic patients, various food items, and pig farms on the Island. HEV strains were characterized by sequencing. A seroprevalence study was also conducted on asymptomatic blood donors before and after the outbreak. One hundred twenty-seven symptomatic cases were reported. Hospitalization was required for 29/127 patients (22.8%). Hospitalized patients presented more frequently with comorbidities, including liver and cardiovascular diseases (80.7% vs. 27%, p < 0.01), and 3 persons died (2.3%). Among the 100 HEV RNA-positive samples received at the French National Reference Centre for HEV, viral sequencing was possible for 76 samples. All strains were identified as HEV genotype 3, and 74/76 strains were grouped together (nucleotide identity: 98%-100%). Full-length sequencing indicated a new HEV-3 subtype within HEV-3 subclade abk. Only genotype 3f strains were detected on the Island's pig farms. No food items tested positive for HEV RNA. The seroprevalence of HEV IgG and IgM in blood donors was 9.2% (9/98) and 0%, respectively, in 2020, rising to 17.3% (17/98) and 2% (2/98) in 2024.

CONCLUSIONS

Although all previous large-scale epidemics in Asia and Africa were associated with HEV-1 or 2, the New Caledonia outbreak was linked to HEV-3. A high number of symptomatic cases were admitted to the hospital, with a case-fatality rate of 2.3%.

Longitudinal serological and virological survey of hepatitis E virus in wild boar (Sus scrofa majori, Maremman wild boar) and fallow deer (Dama dama) populations in a protected area of Central Italy

Hepatitis E virus (HEV) is recognized as an emerging zoonosis. Pigs and wild boars are considered the main reservoirs of zoonotic HEV-3 and HEV-4 genotypes. In Europe, autochthonous human cases of hepatitis E, mainly associated with HEV-3 and consumption of raw or undercooked pig and wild boar liver/meat, have increased over the last decades. From 2016 to 2024, during several hunting seasons, we conducted a molecular and serological longitudinal survey on the circulation of HEV in Maremman wild boar (Italian subspecies/ecotype, Sus scrofa majori) and fallow deer (Dama dama) populations in a protected area in Central Italy. During the study period, 346 livers (256 from wild boar, 90 from fallow deer), 161 serum (127 from wild boar, 34 from fallow deer), and 23 meat juice (11 from wild boar, 12 from fallow deer) samples were collected. Serum and meat juice samples were tested using a commercial ELISA test for the detection of total anti-HEV antibodies. An estimated serological prevalence of 28.3% (39/138) in wild boar and 21.7% (10/46) in fallow deer was found. The 346 liver samples were tested using a HEV Real-Time RT-PCR for the detection of HEV-RNA. Thirty-one wild boar (12%) and four fallow deer (4.4%) livers were found positive. Phylogenetic analysis of 11 partial ORF2 sequences from wild boar confirmed the HEV3 heterogeneity in this species, revealing different strains (3f, 3c) circulating over the years. The detected subtypes are among the most commonly detected in Italy and our strains showed a high correlation with human and wild boar Italian strains. Although the studied area is a fenced natural reserve, the presence of different strains over time suggests the probable virus introduction from the external. Our results confirm fallow deer susceptibility to the infection, and that wild boar could be considered the main wild HEV reservoir. This is also the first study demonstrating the infection in the so-called Italian subspecies/ecotype Maremman wild boar. Moreover, our results corroborate that the consumption of undercooked or raw liver from both wild boar and fallow deer, or the direct contact with these animals, could represent a zoonotic risk.

Hepatitis E and Potential Public Health Implications from a One-Health Perspective: Special Focus on the European Wild Boar (Sus scrofa)

The hepatitis E virus (HEV) has become increasingly important in recent years in terms of risk for public health, as the main causative agent of acute viral hepatitis. It is a foodborne disease transmitted to humans through the consumption of contaminated water or contaminated food. Human-to-human transmission is sporadic and is linked to transfusions or transplants. The main reservoirs of the hepatitis E virus are domestic pigs and wild boars, although, compared to pigs, wild boars represent a lesser source of risk since their population is smaller and the consumption of derived products is more limited. These peculiarities often make the role of the wild boar reservoir in the spread of the disease underestimated. As a public health problem that involves several animal species and humans, the management of the disease requires an interdisciplinary approach, and the concept of "One Health" must be addressed. In this direction, the present review intends to analyze viral hepatitis E, with a particular focus on wild boar. For this purpose, literature data have been collected from different scientific search engines: PubMed, MEDLINE, and Google scholar, and several keywords such as "HEV epidemiology", "Extrahepatic manifestations of Hepatitis E", and "HEV infection control measures", among others, have been used. In the first part, the manuscript provides general information on the disease, such as epidemiology, transmission methods, clinical manifestations and implications on public health. In the second part, it addresses in more detail the role of wild boar as a reservoir and the implications related to the virus epidemiology. The document will be useful to all those who intend to analyze this infectious disease from a "One-Health" perspective.

Epidemiology and multiple colonization of gastrointestinal pathogens in rural Tanzanian children with and without diarrhea: A case-control study

Diarrheal diseases are important causes of morbidity and mortality, worldwide. The occurrence of multiple pathogens in stool samples of symptomatic and asymptomatic individuals in resource-limited countries have been repeatedly described. In this study, we assessed the differentiated effects of combined pathogen detections on recorded symptoms. A case-control study was conducted among 620 under-five-year-old children in rural northeastern Tanzania with emphasis of multiple detection. The median age of children was 11 months (IQR = 7, 20), and 52.1% were male. Cases (50.2%, n = 157) were less likely than controls (64.5%, n = 198) to have multiple colonization with gastrointestinal tract (GIT) pathogens. The children's age was positively associated with the likelihood of harboring multiple GIT pathogens [OR, 1.02, 95% CI = 1.01, 1.04]. Shigella spp./enteroinvasive Escherichia coli (EIEC) [OR = 2.80, 95% CI 1.62, 4.83] and norovirus [OR = 2.04, 95% CI 1.23, 3.39] were more common in cases and were strongly associated with diarrhea, while enteroaggregative E. coli (EAEC) [OR = 0.23, 95%CI 0.17-0.33] were more common in controls. Diarrheal diseases in under-five children from rural Tanzania are likely to be due to infections with Shigella spp./EIEC, and norovirus with strongly age-dependent associations.

Investigating animal reservoirs for hepatitis E virus in Bangui, Central African Republic

BACKGROUND

Hepatitis E virus (HEV) is a major cause of enterotropic viral hepatitis, a major public health problem in many developing countries. In Central African Republic (CAR), HEV genotypes 1, 2, and 3 have been found to have an impact on human health. However, data on HEV in animal reservoirs are still lacking for CAR. Here, we investigated the presence of HEV in farmed pigs and goats in Bangui, the capital city of CAR, using molecular methods.

METHODOLOGY

In a prospective study, fecal samples from 61 pigs and 39 goats from farms in five districts (2nd, 4th, 6th, 7th, 8th) of Bangui were collected and tested for HEV RNA by real-time RT-PCR. The samples were further analyzed by nested-PCR and sequenced to determine the genotype and subtype to which the virus belong.

RESULTS

In total, 22/100 (22.0%) feces samples were successfully amplified for HEV RNA by real time RT-PCR. All positive samples were from pigs (22/61; 36.1%), while all goat samples were negative (0/39). Twelve HEV RNA samples (12/22 or 54.5%) were successfully amplified by nested RT-PCR, and subsequently sequenced. Phylogenetic analysis revealed that the obtained sequences clustered with subtype 3h and were genetically related to the human HEV sequences from CAR.

CONCLUSION

This study confirms that pigs constitute an HEV reservoir, with genotype 3 being the major circulating strain. Further studies are needed to investigate other local reservoirs and to improve knowledge of the molecular epidemiology of HEV in CAR.

Development of a Sensitive and Specific Quantitative RT-qPCR Method for the Detection of Hepatitis E Virus Genotype 3 in Porcine Liver and Foodstuff

As an international and zoonotic cause of hepatitis, hepatitis E virus (HEV) poses a significant risk to public health. However, the frequency of occurrence and the degree of contamination of food of animal origin require further research. The aim of this study was to develop and validate a highly sensitive quantitative RT-qPCR assay for the detection and quantification of HEV contamination in porcine liver and food. The focus was on genotype 3, which is most common as a food contaminant in developed countries and Europe. The selected assay has its target sequence in the open reading frame 1 (ORF1) of the HEV genome and showed good results in inclusivity testing, especially for HEV genotype 3. The developed assay seems to show high efficiency and a low intercept when compared to other assays, while having a comparable limit of detection (LOD). In addition, a standard curve was generated using artificially spiked liver to provide more accurate quantitative results for contamination assessment and tracking in this matrix. Application of the assay to test 67 pig livers from different origins resulted in a positivity rate of 7.5%, which is consistent with the results of numerous other prevalence studies. Quantitative detection of the viral genome in the food chain, particularly in pig livers, is essential for understanding the presence and evolution of HEV contamination and thus ensures consumer safety.

Co-circulation of Hepatitis E Virus (HEV) Genotype 3 and Moose-HEV-Like Strains in Free-Ranging-Spotted Deer (Axis axis) in Uruguay

Hepatitis E caused by hepatitis E virus (HEV) is considered an emerging foodborne zoonosis in industrialized, non-endemic countries. Domestic pigs and wild boars are considered the main reservoir of HEV. However, HEV can also infect an ever-expanding host range of animals, but they exact role in transmitting the virus to other species or humans is mostly unknown. In this work, we investigated the spread of HEV in free-living and captive spotted deer (Axis axis) from Uruguay in a 2-year period (2020-2022) and examined the role of this invasive species as a new potential reservoir of the virus. In addition, with the aim to gain new insights into viral ecology in the context of One Health, by using camera trapping, we identified and quantified temporal and spatial coexistence of spotted deer, wild boars, and cattle. In free-living animals, we detected an anti-HEV seropositivity of 11.1% (6/54). HEV infection and viral excretion in feces were assessed by RT-PCR. Thirteen of 19 samples (68.4%) had HEV RNA. Six samples were amplified using a broadly reactive RT-PCR and sequenced. No captive animal showed evidence of HEV infection. Additionally, HEV RNA was detected in a freshwater pond shared by these species. Phylogenetic and p-distance analysis revealed that zoonotic HEV genotype 3 strains circulate together with unclassified variants related to moose HEV whose potential risk of transmission to humans and other domestic and wild animals is unknown. The data presented here suggest that spotted deer (A. axis) may be a novel host for zoonotic HEV strains.

Evidence of Circulation and Phylogenetic Analysis of Hepatitis E Virus (HEV) in Wild Boar in South-East Italy

Hepatitis E virus (HEV) is an important cause of acute viral hepatitis in humans worldwide. The food-borne transmission of HEV appears to be a major route in Europe through the consumption of pork and wild boar meat. HEV epidemiology in wild boars has been investigated mainly in Northern and Central Italian regions, whilst information from Southern Italy is limited. We investigated the occurrence of HEV in wild boar in the Apulia and Basilicata regions (Southern Italy). Thirteen (10.4%) out of one hundred and twenty-five wild boar samples tested positive for HEV using a quantitative reverse transcription PCR. HEV prevalence was 12% in Apulia and 9.3% in Basilicata. Seven samples were genotyped, and different subtypes (c, f, m) of genotype 3 were identified. The complete genome of a 3m strain was determined, and the virus showed the highest nucleotide identity to a human HEV strain identified in France in 2017. These findings demonstrate the substantial circulation of HEV in the wild boar population in Italian Southern regions. Gathering information on the HEV strains circulating in different geographical areas is useful for tracking the origin of HEV outbreaks and assessing the epidemiological role of wild boar as a potential virus reservoir for domestic pigs.

Hepatitis E Virus in the Wild Boar Population: What Is the Real Zoonotic Risk in Portugal?

Hepatitis E virus (HEV) is an important zoonosis in wild boar. Reported zoonotic cases are mainly associated with the consumption of raw/undercooked meat and/or liver. This study aims to determine the occurrence of HEV in the Portuguese wild boar population. During the hunting season 2021/2022, 123-matched samples (liver, faeces, and blood) were collected from hunted wild boars throughout Portugal. An RT-PCR assay tested liver and faeces samples to detect HEV-RNA. From blood samples, an ELISA test was performed. Only one liver sample was positive for HEV (0,8%) and one other from faeces. A total of 34 sera were seropositive (26.7%). At the same time, in a survey of 106 hunters, 21 consumed/ate the liver of wild boars (19.8%). Only three recognised the possibility of consuming it undercooked. Contrary to previous studies in Portugal, the prevalence of HEV in liver and faeces is low, but the seropositivity is higher. But, when analyzing in detail, it could be observed that an HEV hotspot exists in the southeast of central Portugal and that it is a zoonotic risk for hunters of this region. The data of this study reinforce the importance of including HEV in surveillance programs for wildlife diseases to expand the potential zoonotic information.

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

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

Molecular characterisation of a rabbit Hepatitis E Virus strain detected in a chronically HEV-infected individual from Germany

In immunocompromised individuals persisting viremia frequently leads to a chronic hepatitis E virus (HEV) infection. Zoonotic transmission of HEV from pigs and wild boar to humans is proven and sporadic infections with rabbit HEV (raHEV) have recently been reported. Here, the molecular characterisation of a raHEV strain isolated from an immunocompromised, chronically HEV-infected, heart-transplanted patient is described. After successful ribavirin (RBV) treatment of a HEV infection in 2019, the patient was again tested HEV positive in 2021 and received a second RBV therapy cycle. Full-length HEV genome amplification and next generation sequencing was performed on a plasma sample taken between first and second cycle of RBV therapy and a stool sample taken two months after starting the second cycle. The sequence of plasma (raHEV-83) and stool (raHEV-99) derived virus showed the highest nucleotide sequence identity to a Chinese raHEV and a phylogenetic relationship to a raHEV strain isolated from a French patient. Furthermore, sequence analysis revealed the presence of RBV-associated substitutions V1479I and G1634K in the HEV sequences from plasma and additionally K1398R from stool. The results underline the role of rabbits as putative sources of HEV infection and emphasize the need of a one health concept for a better understanding of HEV epidemiology and to develop tools for prevention and control of HEV infection.

Hepatitis E Virus RNA Detection from Hunted Wild Boars in Central Italy: an Epidemiological Investigation

Every year, foodborne pathogens, including the hepatitis E virus (HEV), cause thousands of infections in different continents. Final consumers become infected through the ingestion of contaminated animal origin foodstuffs. Generally, in industrialized countries, HEV genotype 3 is involved in sporadic outbreaks. Infections have been described, in Europe and Japan as consequence of pork products and contaminated wild boar's primary or processed products (liver and muscle tissues) consumption. In Central Italy, hunting activities are largely practiced. In these small and rural communities, game meat and liver are ingested by hunters' families or at local and traditional restaurants. Therefore, these food chains can be considered critical HEV reservoirs. In this study, 506 liver and diaphragm tissues were collected from hunted wild boars in the Southern Marche region (Central Italy) and were screened for HEV RNA detection. From the 10.87% of liver and 2.76% of muscle samples, HEV3 subtype c was discovered. The observed prevalence values resulted in line with previous investigations performed in other Central Italian regions, but higher than Northern ones (3.7% and 1.9% from liver tissue). Therefore, the obtained epidemiological data highlighted the wide occurrence of HEV RNA circulation in a low-investigated area. Basing on results, a One-health approach was adopted due to the sanitary relevance of this Public Health concern.

Animal reservoirs for hepatitis E virus within the Paslahepevirus genus

Hepatitis E virus (HEV) is responsible for acute hepatitis in humans. It is a single-stranded, positive-sense RNA virus that belongs to the Hepeviridae family. The majority of concerning HEV genotypes belong to the Paslahepevirus genus and are subsequently divided into eight genotypes. HEV genotypes 1 and 2 exclusively infect humans and primates while genotypes 3 and 4 infect both humans and other mammals. Whereas HEV genotypes 5 and 6 are isolated from wild boars and genotypes 7 and 8 were identified from camels in the United Arab Emirates and China, respectively. HEV mainly spreads from humans to humans via the fecal-oral route. However, some genotypes with the capability of zoonotic transmissions, such as 3 and 4 transmit from animals to humans through feces, direct contact, and ingestion of contaminated meat products. As we further continue to uncover novel HEV strains in various animal species, it is becoming clear that HEV has a broad host range. Therefore, understanding the potential animal reservoirs for this virus will allow for better risk management and risk mitigation of infection with HEV. In this review, we mainly focused on animal reservoirs for the members of the species Paslahepevirus balayani and provided a comprehensive list of the host animals identified to date.

Phylodynamic Analysis Suggests That Deer Species May Be a True Reservoir for Hepatitis E Virus Genotypes 3 and 4

Hepatitis E virus (HEV) genotypes 3 and 4 (HEV-3 and HEV-4) cause zoonotic infection in humans, with domestic pigs and wild boars being the main reservoirs of infection. Other than suids, HEV-3 and HEV-4 are found in ruminants, most frequently in deer species. However, it is still debatable, whether HEV infection in deer is a spillover, or indicates a stable virus circulation in these host species. To explore the patterns of HEV-3 and HEV-4 transmission in deer and other host species, we performed a Bayesian analysis of HEV sequences available in GenBank. A total of 27 HEV sequences from different deer species were found in GenBank. Sequences from wild boars collected in the same territories, as well as sequences from all mammals that were most similar to sequences from deer in blast search, were added to the dataset, comprising 617 in total sequences. Due to the presence of partial genomic sequences, they were divided into four subsets (two ORF1 fragments and two ORF2 fragments) and analyzed separately. European HEV-3 sequences and Asian HEV-4 sequences collected from deer species demonstrated two transmission patterns. The first pattern was spillover infection, and the second pattern was deer-to-deer transmission, indicating stable HEV circulation in these species. However, all geographic HEV clusters that contained both deer and swine sequences originated from ancestral swine strains. HEV-3 and HEV-4 transmission patterns in ungulates reconstructed by means of Bayesian analysis indicate that deer species are a true host for HEV. However, wild and domestic swine are often the primary source of infection for ruminants living in the same areas. Complete HEV genomic sequences from different parts of the world are crucial for further understanding the HEV-3 and HEV-4 circulation patterns in wildlife.

Current Knowledge of Hepatitis E Virus (HEV) Epidemiology in Ruminants

Hepatitis E virus (HEV) infection represents an emerging public health concern worldwide. In industrialized countries, increasing numbers of autochthonous cases of human HEV infection are caused by zoonotic transmission of genotypes 3 and 4, mainly through the consumption of contaminated raw or undercooked meat of infected pigs and wild boars, which are considered the main reservoirs of HEV. However, in the last few years, accumulating evidence seems to indicate that several other animals, including different ruminant species, may harbor HEV. Understanding the impact of HEV infection in ruminants and identifying the risk factors affecting transmission among animals and to humans is critical in order to determine their role in the epidemiological cycle of HEV. In this review, we provide a summary of current knowledge on HEV ecology in ruminants. A growing body of evidence has revealed that these animal species may be potential important hosts of HEV, raising concerns about the possible implications for public health.

Co-Circulation of Different Hepatitis E Virus Genotype 3 Subtypes in Pigs and Wild Boar in North-East Germany, 2019

Hepatitis E is a major cause of acute liver disease in humans worldwide. The infection is caused by hepatitis E virus (HEV) which is transmitted in Europe to humans primarily through zoonotic foodborne transmission from domestic pigs, wild boar, rabbits, and deer. HEV belongs to the family Hepeviridae, and possesses a positive-sense, single stranded RNA genome. This agent usually causes an acute self-limited infection in humans, but in people with low immunity, e.g., immunosuppressive therapy or underlying liver diseases, the infection can evolve to chronicity and is able to induce a variety of extrahepatic manifestations. Pig and wild boar have been identified as the primary animal reservoir in Europe, and consumption of raw and undercooked pork is known to pose a potential risk of foodborne HEV infection. In this study, we analysed pig and wild boar liver, faeces, and muscle samples collected in 2019 in Mecklenburg-Western Pomerania, north-east Germany. A total of 393 animals of both species were investigated using quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR), conventional nested RT-PCR and sequence analysis of amplification products. In 33 animals, HEV RNA was detected in liver and/or faeces. In one individual, viral RNA was detected in muscle tissue. Sequence analysis of a partial open reading frame 1 region demonstrated a broad variety of genotype 3 (HEV-3) subtypes. In conclusion, the study demonstrates a high, but varying prevalence of HEV RNA in swine populations in Mecklenburg-Western Pomerania. The associated risk of foodborne HEV infection needs the establishment of sustainable surveillance and treatment strategies at the interface between humans, animals, and the environment within a One Health framework.

Isolation of 15 hepatitis E virus strains lacking ORF1 rearrangements from wild boar and pig organ samples and efficient replication in cell culture

As a zoonotic pathogen, the hepatitis E virus (HEV) leads to numerous infections in humans with different clinical manifestations. Especially genotype 3, as causative agent of a foodborne zoonosis, is transmitted to humans by ingestion of undercooked or raw meat containing liver from HEV-infected animals. Although the virus' prevalence and dissemination in hosts like wild boar and pig have been well characterized, HEV is greatly understudied on a molecular level and reliable cell culture models are lacking. For this reason, the present study concentrated on the isolation and subsequent characterization of porcine HEV from tissue samples derived from wild boar and domestic pigs: 222 wild boars hunted in Northern Germany were investigated for the presence of HEV RNA with a detection rate of 5.9%. Three additional HEV-positive wild boar liver samples as well as an HEV-positive spleen and a positive kidney from domestic pigs were included. After inoculation of positive samples onto the human hepatoma cell line PLC/PRF/5, cells were grown for several weeks. Successful isolation was confirmed by RT-qPCR, virus passage, immunofluorescence staining and titration. Overall, 15 strains from a total of 18 RNA-positive organ samples could be obtained and viral loads >10⁹  RNA copies/ml were measured in cell culture supernatants. Accordingly, 83.3% of the HEV RNA-positive samples contained infectious hepatitis E viral particles and therefore must be considered as a potential source for human infections. Phylogenetic analyses revealed that all isolated strains belong to genotype 3. Further genetic characterization showed a high degree of sequence variability, but no sequence insertions, in the hypervariable region within the open reading frame 1.

Stability of Hepatitis E Virus After Drying on Different Surfaces

The hepatitis E virus (HEV) causes acute and chronic hepatitis in humans. The zoonotic HEV genotype 3 is mainly transmitted by consumption of contaminated food produced from infected animals. However, transmission via contaminated surfaces has also to be considered. Here, the genotype 3c strain 47832c was dried on steel, wood, plastics and ceramics, stored at 23 °C or 3 °C for up to 8 weeks and remaining infectivity was titrated on cell culture. During the drying process, only a mean 0.2 log₁₀ decrease of HEV infectivity was observed. At 23 °C, remaining infectious virus was detected until week 4 on most surfaces, but HEV was completely inactivated (> 4 log₁₀ decrease) after 8 weeks. At 3 °C, HEV was detectable up to 8 weeks on most surfaces, with an average 2.3 log₁₀ decrease. HEV showed the highest stability on plastics, which was lower on ceramics and steel, and lowest on wood. The addition of bovine serum albumin mimicking high protein load had only a slight stabilizing effect. In conclusion, HEV shows a high stability against drying and subsequent storage on different surfaces. Strict application of hygienic measures during food production is therefore crucial in order to prevent HEV persistence on surfaces and subsequent cross-contamination.

Standardised Sampling Approach for Investigating Pathogens or Environmental Chemicals in Wild Game at Community Hunts

Simple Summary

Wild game can host pathogens capable of infecting humans, livestock, and companion animals or accumulate environmental chemicals that may be transferred via food of animal origin. For food safety research, as well as for various other scientific purposes, the provision of a sufficient number of samples without unnecessary disturbance or killing of animals is a major limitation. With the presented approach, it was possible to obtain samples from game animals killed as part of standard ungulate management practice. Examples of organs, tissues, and other matrices that have been used in wild ungulate studies in Europe and that may be obtained through this approach are summarised as well. The basis of this approach was a framework agreement with the BImA, whereby federal forest officials carried out sampling with the help of hunters at drive hunts from 2017/18 to 2020/21 in Brandenburg, Germany. Numerous samples from four ungulate species were obtained. The number of sampled animals per hunt differed between hunting districts and hunting seasons. Districts with higher hunting bags also promise higher sampling success. This approach can serve as the basis for long-term monitoring of animal and public health threats associated with wildlife and is adaptable to other regions.

Abstract

Wildlife may host pathogens and chemicals of veterinary and public health relevance, as well as pathogens with significant economic relevance for domestic livestock. In conducting research on the occurrence and distribution of these agents in wildlife, a major challenge is the acquisition of a sufficient number of samples coupled with efficient use of manpower and time. The aim of this article is to present the methodology and output of a sampling approach for game animals, which was implemented from 2017/18 to 2020/21 at drive hunts in Brandenburg, Germany. The central element was a framework agreement with the BImA, whereby federal forest officials and other hunters collected most of the samples during field dressing. Further samples of game carcasses were obtained by scientists during subsequent gathering at a collection point. Altogether, 3185 samples from 938 wild ungulates of four species were obtained for various studies analysing—in this case—food-borne agents in game animals. Sampling was representative and reflected the proportional distribution of ungulate species hunted in Brandenburg. Hunting district and hunting season strongly influenced hunting bag and hence sampling success. This sampling approach was demonstrated to be a suitable basis for monitoring programs, that can be adapted to other regions.

Phylogeny and spatio-temporal dynamics of hepatitis E virus infections in wild boar and deer from six areas of Germany during 2013-2017

The hepatitis E virus (HEV) can cause acute and chronic hepatitis in humans. Infections with the zoonotic HEV genotype 3, which can be transmitted from infected wild boar and deer to humans, are increasingly detected in Europe. To investigate the spatio-temporal HEV infection dynamics in wild animal populations, a study involving 3572 samples of wild boar and three deer species from six different geographic areas in Germany over a 4-year period was conducted. The HEV-specific antibody detection rates increased between 2013/14 and 2016/17 in wild boar from 9.5% to 22.8%, and decreased in deer from 1.1% to 0.2%. At the same time, HEV-RNA detection rates increased in wild boar from 2.8% to 13.3% and in deer from 0.7% to 4.2%. Marked differences were recorded between the investigated areas, with constantly high detection rates in one area and new HEV introductions followed by increasing detection rates in others. Molecular typing identified HEV subtypes 3c, 3f, 3i and a putative new subtype related to Italian wild boar strains. In areas, where sufficient numbers of positive samples were available for further analysis, a specific subtype dominated over the whole observation period. Phylogenetic analysis confirmed the close relationship between strains from the same area and identified closely related human strains from Germany. The results suggest that the HEV infection dynamics in wild animals is dependent on the particular geographical area where area-specific dominant strains circulate over a long period. The virus can spread from wild boar, which represent the main wild animal reservoir, to deer, and generally from wild animals to humans. This article is protected by copyright. All rights reserved.

Molecular and Pathological Detection of Hepatitis E Virus in Roe Deer (Capreolus capreolus) and Fallow Deer (Dama dama) in Central Italy

Hepatitis E virus (HEV) is a common causative agent of acute hepatitis in the world, with a serious public health burden in both developing and industrialized countries. Cervids, along with wild boars and lagomorphs, are the main wild hosts of HEV in Europe and constitute a documented source of infection for humans. The aim of this study was to evaluate the presence of HEV in roe deer (Capreolus capreolus) and fallow deer (Dama dama) living in Tuscany, Central Italy. Liver samples from 48 roe deer and 60 fallow deer were collected from carcasses during the hunting seasons. Following the results obtained from molecular and histopathologic studies, 5/48 (10.4%) roe deer and 1/60 (1.7%) fallow deer liver samples were positive for the presence of HEV RNA. All PCR-positive livers were also IHC-positive for viral antigen presence, associated with degenerative and inflammatory lesions with predominantly CD3+ cellular infiltrates. This study represents the first identification in Italy of HEV RNA in roe and fallow deer and the first study in literature describing liver alterations associated with HEV infection in cervids. These results demonstrate that HEV is present in wild cervid populations in Italy and confirm the potential zoonotic role of these species.

The concept of one health applied to the problem of zoonotic diseases

Zoonotic diseases are a burden on healthcare systems globally, particularly underdeveloped nations. Numerous vertebrate animals (e.g., birds, mammals and reptiles) serve as amplifier hosts or reservoirs for viral zoonoses. The spread of zoonotic disease is associated with environmental factors, climate change, animal health as well as other human activities including globalization, urbanization and travel. Diseases at the human-animal environment interface (e.g., zoonotic diseases, vector-borne diseases, food/water borne diseases) continue to pose risk to animals and humans with a great significant mortality and morbidity. It is estimated that of 1400 infectious diseases known to affect humans, 60% of them are of animal origin. In addition, 75% of the emerging infectious diseases have a zoonotic nature, worldwide. The one health concept plays an important role in the control and prevention of zoonoses by integrating animal, human, and environmental health through collaboration and communication among osteopaths, wildlife, physicians, veterinarians professionals, public health and environmental experts, nurses, dentists, physicists, biomedical engineers, plant pathologists, biochemists, and others. No one sector, organization, or person can address issues at the animal-human-ecosystem interface alone.

Identification of hepatitis E virus in wild sika deer in Japan

Hepatitis E virus (HEV) is a zoonotic agent mainly transmitted through the consumption of uncooked or undercooked meat products derived from infected animals. In Japan, domestic pigs and wild boars are the major animal reservoirs, and whether or not deer are an HEV reservoir remains controversial. We analyzed 395 serum and 199 liver samples from 405 sika deer (Cervus nippon) caught in the wild between 1997 and 2020 in 11 prefectures of Japan for markers of HEV infection. Overall, 17 deer had anti-HEV IgG (4.3%), while 1 (0.2%) had HEV RNA (genotype 3b), indicating the occurrence of ongoing HEV infection in wild deer in Japan. An analysis of the complete HEV genome (deJOI_14) recovered from a viremic deer in Oita Prefecture revealed only 88.8% identity with the first HEV strain in sika deer (JDEER-Hyo03L) in Japan, being closest (96.3%) to the HEV obtained from a hepatitis patient living in the same prefecture. Of note, the deJOI_14 strain was 8.7-9.0% different from the wild boar HEV strains obtained in the same habitat and the same year, suggesting that difference in infected HEV strains between boar and deer may be explained by the limited possibility of close contact with each other, although boars are a known source of HEV infection. Increased numbers of hepatitis E cases after consumption of raw or undercooked meat products of wild deer have been reported in Japan. These results suggest a low but nonnegligible zoonotic risk of HEV infection in wild deer in this country.

[Hepatitis E virus-a zoonotic virus: distribution, transmission pathways, and relevance for food safety]

Das Hepatitis-E-Virus (HEV) ist ein Erreger einer akuten Hepatitis beim Menschen. Darüber hinaus treten zunehmend auch chronische Infektionen mit fataler Leberzirrhose bei immunsupprimierten Transplantationspatienten auf. Die Zahl der gemeldeten Hepatitis-E-Fälle in Deutschland hat in den vergangenen Jahren stark zugenommen. Hier kommt vor allem der Genotyp 3 vor, der zoonotisch von Tieren auf den Menschen übertragen werden kann. Haus- und Wildschweine, die ohne die Ausbildung klinischer Symptome infiziert werden, stellen das Hauptreservoir dar. In diesem Artikel werden die Verbreitung von HEV in Tieren in Deutschland, mögliche Übertragungswege des Virus und insbesondere die Bedeutung von Lebensmitteln bei der Übertragung anhand der aktuellen wissenschaftlichen Literatur dargestellt.

HEV ist in Haus- und Wildschweinen in Deutschland stark verbreitet und wird hauptsächlich über direkten Kontakt oder den Verzehr von Lebensmitteln, die aus diesen Tieren hergestellt wurden, auf den Menschen übertragen. Beim HEV-RNA-Nachweis in spezifischen Lebensmitteln bleibt allerdings oft unklar, ob das enthaltene Virus noch infektiös ist oder durch die Herstellungsbedingungen inaktiviert wurde. Neuere Studien weisen auf eine hohe Stabilität des HEV unter verschiedenen physikochemischen Bedingungen hin, wohingegen eine Inaktivierung unter anderem durch Erhitzung erreicht wird. Generell wird deshalb ein ausreichendes Erhitzen von Schweinefleisch und -leber vor dem Verzehr empfohlen und für Risikogruppen zusätzlich der Verzicht auf den Verzehr kurzgereifter Rohwürste.

Weitere Forschungen sind nötig, um relevante Risikolebensmittel zu identifizieren, alternative Übertragungswege zu untersuchen und effiziente Maßnahmen zu entwickeln, die eine zoonotische Virusübertragung zukünftig verringern oder vermeiden.

Nationwide survey of hepatitis E virus infection among wildlife in Japan

In Japan, hepatitis E virus (HEV) causes hepatitis in humans through the consumption of raw or undercooked meat, including game meat. In the present study, nationwide surveillance of HEV infection among a total of 5,557 wild animals, including 15 species, was conducted in Japan. The prevalence of anti-HEV antibodies in wild boar was 12.4%, with higher positive rates in big boars (over 50 kg, 18.4%) than in small individuals (less than 30 kg, 5.3%). Furthermore, HEV RNA was more frequently detected in piglets than in older boars. Interestingly, the detection of HEV among wildlife by ELISA and RT-PCR suggested that HEV infection in Sika deer was a very rare event, and that there was no HEV infection among wild animals except for wild boar, Sika deer and Japanese monkeys. In conclusion, wild boar, especially piglets, are at high risk of HEV infection, while other wild animals showed less risk or no risk of HEV transmission.

A systematic review and meta-analysis of hepatitis E virus (HEV) in wild boars

This systematic review and meta-analysis summarize the available information on Hepatitis E virus (HEV) -specific antibody seroprevalence and HEV RNA prevalence in wild boar, one of the most abundant game species worldwide. A literature search (CAB Abstracts, Web of Science, Embase and Scopus) was performed to find relevant peer-reviewed works published during the period 1990-2020. A random-effect model was carried out to calculate the pooled HEV-specific antibody seroprevalence and HEV RNA prevalence estimates with 95% confidence intervals, and I2 statistic was used to assess the heterogeneity of the data. Values by subgroups were compared according to the geographical area, age class (≤ 12 months old and > 12 months old), and sample type (bile, faeces, liver, meat/muscle, serum). Sixty-nine publications were selected, with the majority of the studies from Southern Europe (n = 27). The pooled HEV-specific antibody seroprevalence in wild boar was 28% (CI95% 23-34) and the HEV RNA prevalence 8% (CI95% 6-10). The analysis highlighted a significant heterogeneity among the estimates from the included studies (I2 = 98% and I2 = 95% for HEV-specific antibody seroprevalence and viral prevalence respectively). The moderator analysis indicated a statistically significant difference (p-value = 0.03) for the HEV RNA prevalence according to the sample type, with the highest value in bile (17%, CI95% 9-27), followed by liver (10%, CI95% 7-14), serum (7%, CI95% 4-10), faeces (5%, CI95% 2-9), and meat/muscle (3%, CI95% 0.04-10). Finally, the HEV RNA prevalence in Europe (8.7, CI95% 6.7-11) was significantly (p-value = 0.04) higher than in Asia (4, CI95% 0.6-8). The analysis highlights the important role of wild boar in the epidemiology of HEV.

Serological Evidence of Hepatitis E Virus Infection in Semi-Domesticated Eurasian Tundra Reindeer (Rangifer tarandus tarandus) in Norway

Hepatitis E virus (HEV) is a common cause of viral hepatitis in humans. In developing countries, HEV-infections seem to be mainly associated with pigs, but other animal species may be involved in viral transmission. Recently, anti-HEV antibodies were detected in Norwegian wild reindeer. Here, we investigated anti-HEV seroprevalence in Norwegian semi-domesticated reindeer, animals in closer contact with humans than their wild counterparts. Blood samples (n = 516) were obtained from eight reindeer herds during the period 2013–2017 and analysed with a commercial enzyme-linked immunosorbent assay designed for detecting anti-HEV antibodies in livestock. Antibodies were found in all herds and for all sampling seasons. The overall seroprevalence was 15.7% (81/516), with adults showing a slightly higher seroprevalence (18.0%, 46/256) than calves (13.5%, 35/260, p = 0.11). The seroprevalence was not influenced by gender or latitude, and there was no temporal trend (p > 0.15). A positive association between the presence of anti-HEV antibodies and antibodies against alphaherpesvirus and pestivirus, detected in a previous screening, was found (p < 0.05). We conclude that Norwegian semi-domesticated reindeer are exposed to HEV or an antigenically similar virus. Whether the virus is affecting reindeer health or infects humans and poses a threat for human health remains unknown and warrants further investigations.

Genetic Diversity of Hepatitis E Virus Type 3 in Switzerland-From Stable to Table

Simple Summary

The main hosts of hepatitis E virus (HEV) genotype 3 are porcine species. Transmission of the virus to humans, for example via undercooked meat, may cause acute or chronic hepatitis. To determine sources and routes of infection, comparing the viruses present in humans to the ones present in main hosts is a helpful tool. However, it requires knowledge of the genetic diversity of the circulating viruses. Therefore, we tested Swiss pigs and wild boars for HEV and determined the virus subtype and part of its genome. In addition, we determined the HEV subtype present in 11 positive meat products. One pig liver from the slaughterhouses (0.3%) and seven livers from a carcass collection (13%) as well as seven wild boar livers (5.8%) were found HEV positive. The same virus subtypes were found in Swiss pigs, wild boars, and meat products. Most of the viruses belonged to a Swiss-specific cluster within the subtype 3h. In addition, one pig liver and one wild boar liver were found positive for 3l and two meat products from Germany for 3c. Our data indicate that Switzerland has its “own” HEV viruses that circulate independent from the rest of Europe.

Abstract

Hepatitis E caused by hepatitis E viruses of the genotype 3 (HEV-3) is a major health concern in industrialized countries and due to its zoonotic character requires a “One Health” approach to unravel routes and sources of transmission. Knowing the viral diversity present in reservoir hosts, i.e., pigs but also wild boars, is an important prerequisite for molecular epidemiology. The aim of this study was to gain primary information on the diversity of HEV-3 subtypes present along the food chain in Switzerland, as well as the diversity within these subtypes. To this end, samples of domestic pigs from slaughterhouses and carcass collection points, as well as from hunted wild boars, were tested for HEV RNA and antibodies. HEV positive meat products were provided by food testing labs. The HEV subtypes were determined using Sanger and next generation sequencing. The genetic analyses confirmed the predominance of a Swiss-specific cluster within subtype HEV-3h in pigs, meat products, and wild boars. This cluster, which may result from local virus evolution due to the isolated Swiss pig industry, supports fast differentiation of domestic and imported infections with HEV.

Analysis of seroprevalence data on Hepatitis E virus and Toxoplasma gondii in wild ungulates for the assessment of human exposure to zoonotic meat-borne pathogens

Seroprevalence data for Toxoplasma gondii and Hepatitis E virus (HEV) in wild boar (Sus scrofa), roe deer (Capreolus capreolus), red deer (Cervus elaphus), mouflon (Ovis aries/musimon) and chamois (Rupicapra rupicapra) hunted/culled in northern Italy were used to fit seroprevalence distributions describing the exposure and co-exposure of the species to the two pathogens. The higher proportion of T. gondii and HEV seropositive animals was observed in wild boars with point estimate seroprevalence of 49% (N = 331) and 15% (N = 326) respectively. Data allowed comparisons by area (pre-Alpine Vs Alpine environment) for roe deer, red deer and mouflons. Contrasts between the distributions describing the uncertainty in seroprevalence suggest roe deer, red deer and mouflons have higher probability of being seropositive to T. gondii in pre-Alps. When considering HEV, few seropositive animals were detected and contrasts were symmetrically centred to zero for roe deer and red deer; mouflons shown higher probability of being seropositive in Alpine environment. HEV seropositive animals also included chamois (P = 5.1%, N = 97) in the Alpine districts, confirming circulation of HEV in remote areas. Evidence of HEV and T. gondii co-exposure was limited except for wild boars where it was observed in 30 samples representing 60% of the overall HEV-positive samples. Seroprevalence data of single infection and co-infection are extremely useful to investigate circulation of zoonotic pathogens in wild animals and estimate the foodborne risk of human exposure, however, these type of data do not directly translate into the presence/absence of the pathogen in seropositive and seronegative animals. At benefit of future development of quantitative risk assessments aiming at estimating the risk of human infection/co-infection via consumption of game meat, we developed and made available an online application that allows estimating the probability of the pathogen(s) being present as a function of seroprevalence data.

First molecular detection of hepatitis E virus genome in camel and pig faecal samples in Ethiopia

BACKGROUND

Hepatitis E is an enteric and zoonotic disease caused by hepatitis E virus (HEV) that is mainly transmitted via the faecal-oral route through contaminated food or the environment. The virus is an emerging infectious agent causing acute human infection worldwide. A high seroprevalence of the disease was reported in pregnant women in Addis Ababa, Ethiopia, raising significant public health concern. The presence of HEV specific antibodies were also reported in dromedary camels in the country; however, the infectious virus and/or the viral genome have not been demonstrated to date in animal samples.

METHODS

To address this gap, a total of 95 faecal samples collected from both apparently healthy pigs of uncharacterised types (50 samples) in Burayu and Addis Ababa areas and camels (Camelus dromedarius, 45 samples) in west Hararghe were screened for the presence of HEV genome using universal primers in a fully nested reverse transcription polymerase chain reaction (nRT-PCR). The protocol is capable of detecting HEV in faecal samples from both pigs and camels.

RESULTS

The nRT-PCR detected HEV genes in six (12%) pig faecal samples and one camel sample (2.2%). Therefore, the results indicate that HEV is circulating in both pigs and camels in Ethiopia and these animals and their products could serve as a potential source of infection for humans.

CONCLUSION

The detection of HEV in both animals could raise another concern regarding its public health importance as both animals' meat and camel milk are consumed in the country. Further studies to determine the prevalence and distribution of the virus in different animals and their products, water bodies, food chain, and vegetables are warranted, along with viral gene sequencing for detailed genetic characterisation of the isolates circulating in the country. This information is critically important to design and institute appropriate control and/or preventive measures.

Hepatitis E Virus Persistence and/or Replication in the Peripheral Blood Mononuclear Cells of Acute HEV-Infected Patients

BACKGROUND

Hepatitis E virus (HEV) causes about 14 million infections with 300,000 deaths and 5,200 stillbirths worldwide annually. Extrahepatic manifestations are reported with HEV infections, such as renal, neurological, and hematological disorders. Recently, we reported that stool-derived HEV-1 replicates efficiently in human monocytes and macrophages in vitro. However, another study reports the presence of viral RNA but no evidence of replication in the PBMCs of acute hepatitis E (AHE) patients. Therefore, the replication of HEV in PBMCs during AHE infection is not completely understood.

METHODS

PBMCs were isolated from AHE patients (n = 17) enrolled in Assiut University Hospitals, Egypt. The viral load, positive (+) and negative (-) HEV RNA strands and viral protein were assessed. The gene expression profile of PBMCs from AHE patients was assessed. In addition, the level of cytokines was measured in the plasma of the patients.

RESULTS

HEV RNA was detected in the PBMCs of AHE patients. The median HEV load in the PBMCs was 1.34 × 103 IU/ml. A negative HEV RNA strand and HEV open reading frame 2 protein were recorded in 4/17 (23.5%) of the PBMCs. Upregulation of inflammatory transcripts and increased plasma cytokines were recorded in the AHE patients compared with healthy individuals with significantly elevated transcripts and plasma cytokines in the AHE with detectable (+) and (-) RNA strands compared with the AHE with the detectable (+) RNA strand only. There was no significant difference in terms of age, sex, and liver function tests between AHE patients with detectable (+) and (-) RNA strands in the PBMCs and AHE patients with the (+) RNA strand only.

CONCLUSION

Our study shows evidence for in vivo HEV persistence and replication in the PBMCs of AHE patients. The replication of HEV in the PBMCs was associated with an enhanced immune response, which could affect the pathogenesis of HEV.

Seroprevalence of the hepatitis E virus antibodies among blood donors in the Qassim region, Saudi Arabia

Aim: Hepatitis E virus (HEV) transmission through blood transfusion is a major public health issue worldwide. We aimed to determine the seroprevalence of HEV in blood donors in the Qassim region of Saudi Arabia. Materials & methods: Serum samples (n = 1078) were collected from volunteer blood donors and tested for the presence of anti-HEV IgG and IgM by indirect ELISA. Results: The seroprevalence of anti-HEV IgG among the blood donors was 5.7% overall. Anti-HEV IgG and IgM seropositivity were significantly higher in non-Saudi donors than in Saudi donors (22.1 vs 3 and 7.8 vs 0.2% for anti-HEV IgG and IgM, respectively). Conclusion: The seroprevalence of HEV among blood donors in the Qassim region was lower than previous estimates for other regions of the country and neighboring countries.

Hepatitis E Virus (HEV) Spread and Genetic Diversity in Game Animals in Northern Italy

Hepatitis E virus (HEV) is the causative agent of hepatitis E, an emerging public health infection which has an increasing incidence across Europe. Because of the apparent lack of species barriers, HEV was characterized as a zoonotic agent. Swine are recognized as the main reservoir, but HEV is also found in wild animals such as ungulates, lagomorphs, and bats. Our work aimed at detecting the HEV presence in wild fauna in two hunting areas of Northern Italy (Parma and Sondrio areas) with different environmental and anthropic characteristics to investigate its possible role as reservoir. Liver samples were collected from wild boars, red deer, roe deer and chamois, and viral identification was carried out by One-Step RT Real-time PCR. Positive samples were genotyped, and phylogenetic analysis was performed. The virus was found only in the wild boar population, with different prevalence and subtypes in the two areas (14% HEV3a and 1.2% close to HEV3f in Parma and Sondrio, respectively). Wild ruminants seem otherwise to pose a marginal risk. Given the high pig farm density in the Parma area, and expansion of the wild boar population, continuous monitoring of the strains circulating in wildlife is crucial.

The Foodborne Transmission of Hepatitis E Virus to Humans

Globally, Hepatitis E virus (HEV) causes over 20 million cases worldwide. HEV is an emerging and endemic pathogen within economically developed countries, chiefly resulting from infections with genotype 3 (G3) HEV. G3 HEV is known to be a zoonotic pathogen, with a broad host range. The primary source of HEV within more economically developed countries is considered to be pigs, and consumption of pork products is a significant risk factor and known transmission route for the virus to humans. However, other foods have also been implicated in the transmission of HEV to humans. This review consolidates the information available regarding transmission of HEV and looks to identify gaps where further research is required to better understand how HEV is transmitted to humans through food.

Open reading frame 3 protein of hepatitis E virus: Multi-function protein with endless potential

Hepatitis E virus (HEV), a fecal-orally transmitted foodborne viral pathogen, causes acute hepatitis in humans and is responsible for hepatitis E outbreaks worldwide. Since the identification of HEV as a zoonotic agent, this virus has been isolated from a variety of hosts with an ever-expanding host range. HEV-open reading frame (ORF) 3, the smallest ORF in HEV genomes, initially had been perceived as an unremarkable HEV accessory protein. However, as novel HEV-ORF3 function has been discovered that is related to the existence of a putative third virion structural form, referred to as “quasi-enveloped” HEV particles, HEV is challenging the conventional virion structure-based classification scheme, which assigns all viruses to two groups, “enveloped” or “non-enveloped”. In this review, we systematically describe recent progress that has identified multiple pathogenic roles of HEV-ORF3, including roles in HEV virion release, biogenesis of quasi-enveloped virus, regulation of the host innate immune response, and interference with host signaling pathways. In addition, implications of HEV-ORF3-associated quasi-enveloped virions are discussed to guide future development of improved vaccines against zoonotic HEV infection.

Serological Evidence of Hepatitis E Virus Circulation Among Reindeer and Reindeer Herders

Various deer species are infected with hepatitis E virus (HEV) and may be a source of zoonotic infection for humans. So far, HEV has not been isolated from reindeer and the role of this domesticated deer species in HEV transmission is unknown. We tested serum samples from 191 reindeer (Rangifer tarandus) and 86 adult reindeer herders from the circumpolar regions of Yakutia (Russian Federation) for anti-HEV and HEV RNA. Anti-HEV IgG prevalence was 12.0% (95% confidence interval [95% CI]: 8.1-17.5) in reindeer and 4.7% (95% CI: 1.5-11.7) in reindeer herders. The latter was similar to the positivity rate observed in adult residents of the city of Yakutsk, the capital of Yakutia, who do not have routine contact with reindeer (3.7% [19/519, 95% CI: 2.3-5.7]). No samples positive for HEV RNA were identified. The study provides evidence of HEV circulation in reindeer. Nevertheless, the low seroprevalence in reindeer herders indicate a low risk of zoonotic HEV infection.

Study of enteric pathogens among children in the tropics and effects of prolonged storage of stool samples

The study was performed to compare real-time PCR after nucleic acid extraction directly from stool samples as well as from samples stored and transported on Whatman papers or flocked swabs at ambient temperature in the tropics. In addition, the possible suitability for a clear determination of likely aetiological relevance of PCR-based pathogen detections based on cycle threshold (Ct) values was assessed. From 632 Tanzanian children <5 years of age with and without gastrointestinal symptoms, 466 samples were subjected to nucleic acid extraction and real-time PCR for gastrointestinal viral, bacterial and protozoan pathogens. Equal or even higher frequencies of pathogen detections from Whatman papers or flocked swabs were achieved compared with nucleic acid extraction directly from stool samples. Comparison of the Ct values showed no significant difference according to the nucleic acid extraction strategy. Also, the Ct values did not allow a decision whether a detected pathogen was associated with gastrointestinal symptoms.

Seroprevalence of Hepatitis E Virus Infection Among Wild Boars in Western Bulgaria

Scientific evidence indicates that hepatitis E virus (HEV) infection is a zoonotic disease. Domestic pigs and wild boars are the main animal reservoir for HEV worldwide. The aim of this study was to analyze the seroprevalence of HEV infection among wild boars in western Bulgaria. Serum samples from 240 wild boars from two regions of the country (northwestern and southwestern) were tested for anti-HEV Immunoglobulin G (IgG) antibodies. The overall HEV seroprevalence was 40.8% (98/240); northwestern region 40.0% (48/120); southwestern region 41.7% (50/120). HEV seropositivity in the southwestern region was higher than in the northwestern region: odds ratio = 1.071 (95% confidence interval: 0.640-1.793). This research provided the first seroprevalence study to HEV in wild boars from western Bulgaria.

Advances in Hepatitis E Virus Biology and Pathogenesis

Hepatitis E virus (HEV) is one of the causative agents for liver inflammation across the world. HEV is a positive-sense single-stranded RNA virus. Human HEV strains mainly belong to four major genotypes in the genus Orthohepevirus A, family Hepeviridae. Among the four genotypes, genotype 1 and 2 are obligate human pathogens, and genotype 3 and 4 cause zoonotic infections. HEV infection with genotype 1 and 2 mainly presents as acute and self-limiting hepatitis in young adults. However, HEV infection of pregnant women with genotype 1 strains can be exacerbated to fulminant hepatitis, resulting in a high rate of case fatality. As pregnant women maintain the balance of maternal-fetal tolerance and effective immunity against invading pathogens, HEV infection with genotype 1 might dysregulate the balance and cause the adverse outcome. Furthermore, HEV infection with genotype 3 can be chronic in immunocompromised patients, with rapid progression, which has been a challenge since it was reported years ago. The virus has a complex interaction with the host cells in downregulating antiviral factors and recruiting elements to generate a conducive environment of replication. The virus-cell interactions at an early stage might determine the consequence of the infection. In this review, advances in HEV virology, viral life cycle, viral interference with the immune response, and the pathogenesis in pregnant women are discussed, and perspectives on these aspects are presented.

Seroprevalence of Hepatitis E Virus in Moose (Alces alces), Reindeer (Rangifer tarandus), Red Deer (Cervus elaphus), Roe Deer (Capreolus capreolus), and Muskoxen (Ovibos moschatus) from Norway

Hepatitis E virus (HEV), a major cause of viral hepatitis worldwide, is considered an emerging foodborne zoonosis in Europe. Pigs (Sus scrofa domestica) and wild boars (S. scrofa) are recognized as important HEV reservoirs. Additionally, HEV infection and exposure have been described in cervids. In Norway, HEV has been identified in pigs and humans; however, little is known regarding its presence in wild ungulates in the country. We used a species-independent double-antigen sandwich ELISA to detect antibodies against HEV in the sera of 715 wild ungulates from Norway, including 164 moose (Alces alces), 186 wild Eurasian tundra reindeer (Rangifer tarandus tarandus), 177 red deer (Cervus elaphus), 86 European roe deer (Capreolus capreolus), and 102 muskoxen (Ovibos moschatus). The overall seroprevalence was 12.3% (88/715). Wild reindeer had the highest seropositivity (23.1%, 43/186), followed by moose (19.5%, 32/164), muskoxen (5.9%, 6/102), and red deer (4%, 7/177). All roe deer were negative. According to our results, HEV is circulating in wild ungulates in Norway. The high seroprevalence observed in wild reindeer and moose indicates that these species may be potential reservoirs of HEV. To the authors’ knowledge, this is the first report of HEV exposure in reindeer from Europe and in muskoxen worldwide.

Model systems for studying extrahepatic pathogenesis of hepatitis E virus. Current knowledge and future directions

Hepatitis E Virus is the most common cause of acute viral hepatitis globally. HEV infection is endemic in developing countries. Also, autochthonous and sporadic cases are reported in developed countries. HEV causes acute and chronic infections. Besides, extrahepatic manifestations including neurological, renal, haematological, acute pancreatitis and complications during pregnancy are associated with HEV infections. The pathogenesis of HEV in the extrahepatic tissues is either due to direct cytopathic effect mediated by the virus replication, or immunological mechanisms caused by an uncontrollable host response. Researchers have used different in vivo and in vitro models to study the pathogenesis of HEV in the extrahepatic tissues and analyse the host immune response against HEV infection. This review highlights the extrahepatic disorders associated with HEV infection. We focused on the in vivo and in vitro models as a tool for elucidating the HEV infection beyond the liver and studying the mechanisms of HEV induced tissue damages.

Surveillance Study of Hepatitis E Virus (HEV) in Domestic and Wild Ruminants in Northwestern Italy

Simple Summary

Hepatitis E virus (HEV) infection can cause both acute and chronic hepatitis in humans and represents an emerging public health concern worldwide. In developed countries, zoonotic transmission of HEV genotypes 3 and 4 is caused by ingestion of raw or undercooked meat of infected swine or wild boars, the main reservoirs of HEV. However, in the last few years, molecular and serological evidence seem to indicate that several other animal species may act as HEV host, including domestic and wild ruminants. In this study, serum and fecal specimens from sheep, goats, red deer, roe deer, chamois, and Alpine ibex collected in two northwestern Italian regions (Piemonte and Valle d’Aosta) were screened molecularly and serologically. With the exception of chamois, HEV antibodies were found both in the domestic and wild ruminant species investigated with the highest rates in sheep and goats. These findings demonstrate that wild also domestic ruminants may be implicated in the viral cycle transmission.

Abstract

In industrialized countries, increasing autochthonous infections of hepatitis E virus (HEV) are caused by zoonotic transmission of genotypes (Gts) 3 and 4, mainly through consumption of contaminated raw or undercooked pork meat. Although swine and wild boar are recognized as the main reservoir for Gt3 and Gt4, accumulating evidence indicates that other animal species, including domestic and wild ruminants, may harbor HEV. Herein, we screened molecularly and serologically serum and fecal samples from two domestic and four wild ruminant species collected in Valle d’Aosta and Piemonte regions (northwestern Italy. HEV antibodies were found in sheep (21.6%), goats (11.4%), red deer (2.6%), roe deer (3.1%), and in Alpine ibex (6.3%). Molecular screening was performed using different primer sets targeting highly conserved regions of hepeviruses and HEV RNA, although at low viral loads, was detected in four fecal specimens (3.0%, 4/134) collected from two HEV seropositive sheep herds. Taken together, the data obtained document the circulation of HEV in the geographical area assessed both in wild and domestic ruminants, but with the highest seroprevalence in sheep and goats. Consistently with results from other studies conducted in southern Italy, circulation of HEV among small domestic ruminants seems to occur more frequently than expected.

Foodborne Zoonoses Common in Hunted Wild Boars

The northern European wild boar population has increased during the last decade. Highest wild boar numbers in Finland have been reported in the southeastern part near the Russian border. Wild boars may be infected with several human and animal pathogens. In this study, we investigated the presence of important foodborne pathogens in wild boars hunted in 2016 in Finland using serology, PCR and culturing. Seroprevalence of Salmonella (38%) and Yersinia (56%) infections was high in wild boars. Antibodies to hepatitis E virus, Toxoplasma gondii and Brucella were found in 18%, 9% and 9% of the wild boars, respectively. Trichinella antibodies were detected in 1% of the animals. We recorded no differences in the seroprevalence between males and females. However, Yersinia and T. gondii antibodies were detected significantly more often in adults than in young individuals. Listeria monocytogenes (48%) and stx-positive Escherichia coli (33%) determinants were frequently detected in the visceral organs (spleen and kidneys) by PCR. Yersinia pseudotuberculosis O:1 and L. monocytogenes 2a and 4b were identified by culturing from the PCR-positive samples. Brucella suis biovar 2 was isolated from visceral organs. No African swine fever, classical swine fever or Aujeszky's disease were detected in the wild boars. Our study shows that wild boars are important reservoirs of foodborne pathogens.

Antibodies Against Hepatitis E Virus (HEV) in European Moose and White-Tailed Deer in Finland

The main animal reservoirs of zoonotic hepatitis E virus (HEV) are domestic pigs and wild boars, but HEV also infects cervids. In this study, we estimated the prevalence of HEV in Finnish cervid species that are commonly hunted for human consumption. We investigated sera from 342 European moose (Alces alces), 70 white-tailed deer (Odocoileus virginianus), and 12 European roe deer (Capreolus capreolus). The samples had been collected from legally hunted animals from different districts of Finland during 2008-2009. We analysed the samples for total anti-HEV antibodies using a double-sandwich ELISA assay. Seropositive sera were analysed with RT-qPCR for HEV RNA. HEV seroprevalence was 9.1% (31/342) in moose and 1.4% (1/70) in white-tailed deer. None of the European roe deer were HEV seropositive (0/12). No HEV RNA was detected from samples of seropositive animals. HEV seropositive moose were detected in all districts. Statistically, HEV seroprevalence in moose was significantly higher (p < 0.05) in the North-East area compared to the South-West area. The highest HEV seroprevalence (20.0%) in district level was more than six times higher than the lowest (3.1%). We demonstrated the presence of total anti-HEV antibodies in European moose and white-tailed deer in Finland. Our results suggest that HEV is circulating among the moose population. Infections may occur also in white-tailed deer. We were the first to report a HEV seropositive white-tailed deer from Europe. Further studies are needed to demonstrate the HEV genotypes in cervids in Finland and to evaluate the importance of the findings in relation to food safety.