Hepatitis E virus in bottlenose dolphins Tursiops truncatus

Survey of selected viral agents (herpesvirus, adenovirus and hepatitis E virus) in liver and lung samples of cetaceans, Brazil

Hepatic and pulmonary lesions are common in cetaceans, despite their poorly understood viral etiology. Herpesviruses (HV), adenoviruses (AdV) and hepatitis E virus (HEV) are emerging agents in cetaceans, associated with liver and/or pulmonary damage in mammals. We isolated and molecularly tested DNA for HV and AdV (n = 218 individuals; 187 liver and 108 lung samples) and RNA for HEV (n = 147 animals; 147 liver samples) from six cetacean families. All animals stranded or were bycaught in Brazil between 2001 and 2021. Positive-animals were analyzed by histopathology. Statistical analyses assessed if the prevalence of viral infection could be associated with the variables: species, family, habitat, region, sex, and age group. All samples were negative for AdV and HEV. Overall, 8.7% (19/218) of the cetaceans were HV-positive (4.8% [9/187] liver and 11.1% [12/108] lung), without HV-associated lesions. HV-prevalence was statistically significant higher in Pontoporiidae (19.2%, 10/52) when compared to Delphinidae (4.1%, 5/121), and in southeastern (17.1%, 13/76)-the most industrialized Brazilian region-when compared to the northeastern region (2.4%, 3/126). This study broadens the herpesvirus host range in cetaceans, including its description in pygmy sperm whales (Kogia breviceps) and humpback whales (Megaptera novaeangliae). Further studies must elucidate herpesvirus drivers in cetaceans.

Whole genome sequencing reveals insights into hepatitis E virus genome diversity, and virus compartmentalization in chronic hepatitis E

BACKGROUND

Hepatitis E virus (HEV) is a leading cause of acute hepatitis and can cause chronic infections in immunocompromised patients. Although HEV infections can be treated with ribavirin, antiviral efficacy is hampered by resistance mutations, normally detected by virus sequencing.

OBJECTIVES

High-throughput sequencing (HTS) allows for cost-effective complete viral genome sequencing. This enables the discovery and delineation of new subtypes, and revised the recognition of quasispecies and putative resistance mutations. However, HTS is challenged by factors including low viral load, sample degradation, high host background, and high viral diversity.

STUDY DESIGN

We apply complete genome sequencing strategies for HEV, including a targeted enrichment approach. These approaches were used to investigate sequence diversity in HEV RNA-positive animal and human samples and intra-host diversity in a chronically infected patient.

RESULTS

Here, we describe the identification of potential novel subtypes in a blood donation (genotype 3) and in an ancient livestock sample (genotype 7). In a chronically infected patient, we successfully investigated intra-host virus diversity, including the presence of ribavirin resistance mutations. Furthermore, we found convincing evidence for HEV compartmentalization, including the central nervous system, in this patient.

CONCLUSIONS

Targeted enrichment of viral sequences enables the generation of complete genome sequences from a variety of difficult sample materials. Moreover, it enables the generation of greater sequence coverage allowing more advanced analyses. This is key for a better understanding of virus diversity. Investigation of existing ribavirin resistance, in the context of minorities or compartmentalization, may be critical in treatment strategies of HEV patients.

Tracing the History of Hepatitis E Virus Infection in Mexico: From the Enigmatic Genotype 2 to the Current Disease Situation

Hepatitis E virus (HEV) is the major cause of acute viral hepatitis worldwide. This virus is responsible for waterborne outbreaks in low-income countries and zoonosis transmission in industrialized regions. Initially, considered self-limiting, HEV may also lead to chronic disease, and evidence supports that infection can be considered a systemic disease. In the late 1980s, Mexico became a hot spot in the study of HEV due to one of the first virus outbreaks in Latin America related to enterically transmitted viral non-A, non-B hepatitis. Viral stool particles recovered from Mexican viral hepatitis outbreaks represented the first identification of HEV genotype (Gt) 2 (Gt2) in the world. No new findings of HEV-Gt2 have been reported in the country, whereas this genotype has been found in countries on the African continent. Recent investigations in Mexico have identified other strains (HEV-Gt1 and -Gt3) and a high frequency of anti-HEV antibodies in animal and human populations. Herein, the potential reasons for the disappearance of HEV-Gt2 in Mexico and the advances in the study of HEV in the country are discussed along with challenges in studying this neglected pathogen. These pieces of information are expected to contribute to disease control in the entire Latin American region.

First Insight into the Seroepidemiology of Hepatitis E Virus (HEV) in Dogs, Cats, Horses, Cattle, Sheep, and Goats from Bulgaria

In recent years, hepatitis E virus (HEV) infection has been found to be widespread among different animal species worldwide. In Bulgaria, high HEV seropositivity was found among pigs (60.3%), wild boars (40.8%), and East Balkan swine (82.5%). The aim of the present study was to establish the seroprevalence of HEV among dogs, cats, horses, cattle, sheep, and goats in Bulgaria. In total, 720 serum samples from six animal species were randomly collected: dogs-90 samples; cats-90; horses-180; cattle-180; sheep-90; and goats-90. The serum samples were collected from seven districts of the country: Burgas, Kardzhali, Pazardzhik, Plovdiv, Sliven, Smolyan, and Stara Zagora. The animal serum samples were tested for HEV antibodies using the commercial Wantai HEV-Ab ELISA kit (Beijing, China). The overall HEV seroprevalence among different animal species from Bulgaria was as follows: dogs-21.1%; cats-17.7%; horses-8.3%; cattle-7.7%; sheep-32.2%; and goats-24.4%. We found the lowest overall HEV seropositivity in Plovdiv district (6.2%; 4/64; p = 0.203) and Smolyan district (8.8%; 4/45; p = 0.129), vs. the highest in Pazardzhik district (21.6%; 29/134; p = 0.024) and Burgas district (28.8%; 26/90; p = 0.062). To the best of our knowledge, this is the first serological evidence of HEV infection in dogs, cats, horses, cattle, sheep, and goats from Bulgaria. We found high HEV seropositivity in small ruminants (sheep and goats), moderate seropositivity in pets (dogs and cats), and a low level of seropositivity in large animals (horses and cattle). Previous Bulgarian studies and the results of this research show that HEV infection is widespread among animals in our country. In this regard, the Bulgarian health authorities must carry out increased surveillance and control of HEV infection among animals in Bulgaria.

Hepatitis E Virus (HEV) Infection among Humans and Animals: Epidemiology, Clinical Characteristics, Treatment, and Prevention

The public health significance of hepatitis E is very important [...].

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.

Development of an Extraction Method to Detect Hepatitis A Virus, Hepatitis E Virus, and Noroviruses in Fish Products

Viruses are a leading cause of foodborne disease worldwide. Hepatitis viruses (hepatitis A (HAV) and hepatitis E (HEV)) and human norovirus are recognized as the main viruses of public health concern in food hygiene. ISO 15216 approved procedures are not validated for detection of HAV and human norovirus in foodstuffs, such as fishes, leading to an inability to ensure the safety of these products. This study aimed to provide a rapid and sensitive method for detecting these targets in fish products. An existing method that includes proteinase K treatment was selected for further validation using artificially contaminated fish products, according to the recent international standard ISO 16140-4. Recovery efficiencies in pure RNA extracts of viruses ranged from 0.2% to 66.2% for HAV, 4.0% to 100.0% for HEV, 2.2% to 100.0% for norovirus GI, and 0.2% to 12.5% for norovirus GII. LOD50 values were between 144 and 8.4 × 104 genome copies/g for HAV and HEV, and 104 and 2.0 × 103 copies/g for norovirus GI and norovirus GII, respectively. LOD95 values were between 3.2 × 103 and 3.6 × 105 genome copies/g for HAV and HEV, and between 8.8 × 103 and 4.4 × 104 genome copies/g for norovirus GI and norovirus GII, respectively. The method developed here was successfully validated in various fish products and can be applied for routine diagnostic needs.

Detection of Hepatitis E Virus Genotype 3 in Feces of Capybaras (Hydrochoeris hydrochaeris) in Brazil

Hepatitis E virus (HEV) is an emerging zoonotic pathogen associated with relevant public health issues. The aim of this study was to investigate HEV presence in free-living capybaras inhabiting urban parks in São Paulo state, Brazil. Molecular characterization of HEV positive samples was undertaken to elucidate the genetic diversity of the virus in these animals. A total of 337 fecal samples were screened for HEV using RT-qPCR and further confirmed by conventional nested RT-PCR. HEV genotype and subtype were determined using Sanger and next-generation sequencing. HEV was detected in one specimen (0.3%) and assigned as HEV-3f. The IAL-HEV_921 HEV-3f strain showed a close relationship to European swine, wild boar and human strains (90.7-93.2% nt), suggesting an interspecies transmission. Molecular epidemiology of HEV is poorly investigated in Brazil; subtype 3f has been reported in swine. This is the first report of HEV detected in capybara stool samples worldwide.

Puzzles for Hepatitis E Virus

Hepatitis E virus (HEV) is an important but understudied virus that has been the major cause of acute viral hepatitis worldwide. In recent decades, our understanding of this neglected virus has changed greatly: novel forms of viral proteins and their functions have been discovered; HEV can transmit via blood transfusion and organ transplantation; HEV can infect many animal species and the number is still increasing; HEV can induce chronic hepatitis and extra-hepatic manifestations. However, we are short of effective treatment measures to counter the virus. In this chapter we tend to briefly introduce the puzzles and major knowledge gaps existed in the field of HEV research.

Hepatitis E as a Zoonosis

Hepatitis E viruses in the family of Hepeviridae have been classified into 2 genus, 5 species, and 13 genotypes, involving different animal hosts of different habitats. Among all these genotypes, four (genotypes 3, 4, 7, and C1) of them are confirmed zoonotic causing sporadic human diseases, two (genotypes 5 and 8) were likely zoonotic showing experimental animal infections, and the other seven were not zoonotic or unconfirmed. These zoonotic HEV carrying hosts include pig, boar, deer, rabbit, camel, and rat. Taxonomically, all the zoonotic HEVs belong to the genus Orthohepevirus, which include genotypes 3, 4, 5, 7, 8 HEV in the species A and genotype C1 HEV in the species C. In the chapter, information of zoonotic HEV such as swine HEV (genotype 3 and 4), wild boar HEV (genotypes 3-6), rabbit HEV (genotype 3), camel HEV (genotype 7 and 8), and rat HEV (HEV-C1) was provided in detail. At the same time, their prevalence characteristics, transmission route, phylogenetic relationship, and detection technology were discussed. Other animal hosts of HEVs were introduced briefly in the chapter. All these information help peer researchers have basic understanding of zoonotic HEV and adopt reasonable strategy of surveillance and prevention.

Hepatitis E Virus Infections in Free-Ranging and Captive Cetaceans, Spain, 2011-2022

Epidemiologic surveillance of hepatitis E virus in over 300 free-ranging and captive cetaceans in waters off Spain revealed extensive exposure to this pathogen. We suggest the persistent and widespread presence of hepatitis E in the marine environment off the coast of Spain may be driven by terrestrial sources of contamination.

Hepatitis E: Genotypes, strategies to prevent and manage, and the existing knowledge gaps

Hepatitis E virus (HEV) is considered an emergent source of viral hepatitis worldwide, with an increasing burden of jaundice, liver failure, extrahepatic illnesses, and deaths in developed countries. With the scarcity of data from efficient animal models, there are still open-ended questions about designing new models to study pathogenesis, types, virology, and evolution of these viruses. With an emphasis on available data and updates, there is still enough information to understand the HEV life cycle, pathogen interaction with the host, and the valuation of the role of vaccine and new anti-HEV therapies. However, the World Health Organization (WHO) and the European Association for the Study of the Liver (EASL) preferred to stress prevention and control measures of HEV infections in animals, zoonotic transmission, and foodborne transmission. It is being reviewed that with current knowledge on HEV and existing prevention tools, there is an excellent room for in-depth information about the virus strains, their replication, pathogenicity, and virulence. The current knowledge set also has gaps regarding standardized and validated diagnostic tools, efficacy and safety of the vaccine, and extrahepatic manifestations specifically in pregnant females, immunocompromised patients, and others. This review highlights the areas for more research exploration, focusing on enlisted research questions based on HEV infection to endorse the need for significant improvement in the current set of knowledge for this public health problem.

Epidemiology of Hepatitis E in 2017 in Bavaria, Germany

In the last decade, the number of reported hepatitis E virus (HEV) infections in Germany, including Bavaria, has continued to rise. In order to identify risk factors associated with HEV infection, we investigated notified hepatitis E cases from Bavaria during 2017. The project "Intensified Hepatitis E Surveillance in Bavaria" included interviews with questionnaires, collection and genotyping of stool, serum and food samples. In addition, certain risk factors were examined in a sample comparison with healthy population using univariable analysis and logistic regression. In total, 135 hepatitis E cases from Bavaria were included in the analysis. Mean age for women was 46 (range 20-74) years and 47.5 (range 20-85) for men. 56 of the cases (41.5%) were asymptomatic. Among the symptomatic cases, both men and women were equally affected with symptoms like fever (16.3%), jaundice (18.8%) and upper abdominal pain (28.2%). 145 human samples (serum, stool) and 6 food samples were collected. 15.9% of the human samples (n = 23) were positive for HEV RNA by reverse-transcription quantitative real-time PCR (RT-qPCR). Identified risk factors significantly associated with hepatitis E were sausage consumption with odds ratio 9.6 (CI 1.3-70.1), fish with OR 2.2 (CI 1.1-4.4) and cat ownership with OR 1.9 (CI 1.3-3.0) in multivariable analyses. Further investigation is needed to confirm the role of fish in HEV transmission. Autochthonous HEV genotype 3 is prevalent in Bavaria and there could be more transmission routes contributing to the spread of HEV than previously known. Undercooked meat, offal, sausages, fish, shellfish and contact with animals and pets are possible sources for infection.

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.

Hepatitis E Virus in the Food of Animal Origin: A Review

Hepatitis E virus (HEV) is a cosmopolitan foodborne pathogen. The viral agent infects humans through the consumption of contaminated food (uncooked or undercooked). Most cases of infection are asymptomatic and for this reason, this pathology is considered underdiagnosed. Domestic and wild animals are considered natural reservoirs: that is, domestic pig, wild boar, sheep, goat, deer, rabbit, and so on. Therefore, various work categories are at risk: that is, veterinarians, farmers, hunters, slaughterhouse workers, and so on. In these last decades, researchers found a high percentage of positivity to the molecular viral detection in several food matrices included: ready-to-eat products, processed meat products, milk, and shellfish. This review aims to provide an international scenario regarding HEV ribonucleic acid (RNA) detection in several foodstuffs. From this investigative perspective, the study aims to highlight various gaps of the current knowledge about technologies treatments' impact on viral loads. The purpose was also to provide an innovative point of view "One Health"-based, pointing out the strategic role of environmental safety.

Hepatitis E Virus Infection: Is It Really a Problem in Latin America?

Watch a video presentation of this article.

Genetic Variability and Evolution of Hepatitis E Virus

Hepatitis E virus (HEV) is a single-stranded positive-sense RNA virus. HEV can cause both acute and chronic hepatitis, with the latter usually occurring in immunocompromised patients. Modes of transmission range from the classic fecal-oral route or zoonotic route, to relatively recently recognized but increasingly common routes, such as via the transfusion of blood products or organ transplantation. Extrahepatic manifestations, such as neurological, kidney and hematological abnormalities, have been documented in some limited cases, typically in patients with immune suppression. HEV has demonstrated extensive genomic diversity and a variety of HEV strains have been identified worldwide from human populations as well as growing numbers of animal species. The genetic variability and constant evolution of HEV contribute to its physiopathogenesis and adaptation to new hosts. This review describes the recent classification of the Hepeviridae family, global genotype distribution, clinical significance of HEV genotype and genomic variability and evolution of HEV.

The Current Host Range of Hepatitis E Viruses

Hepatitis E virus (HEV) is an emerging zoonotic pathogen transmitting both human to human via the fecal oral route and from animals to humans through feces, direct contact, and consumption of contaminated meat products. Understanding the host range of the virus is critical for determining where potential threats to human health may be emerging from and where potential reservoirs for viral persistence in the environment may be hiding. Initially thought to be a human specific disease endemic to developing countries, the identification of swine as a primary host for genotypes 3 and 4 HEV in industrialized countries has begun a long journey of discovering novel strains of HEV and their animal hosts. As we continue identifying new strains of HEV in disparate animal species, it is becoming abundantly clear that HEV has a broad host range and many of these HEV strains can cross between differing animal species. These cross-species transmitting strains pose many unique challenges to human health as they are often unrecognized as sources of viral transmission.

Cyanobacterial neurotoxin BMAA and brain pathology in stranded dolphins

Dolphin stranding events occur frequently in Florida and Massachusetts. Dolphins are an excellent sentinel species for toxin exposures in the marine environment. In this report we examine whether cyanobacterial neurotoxin, β-methylamino-L-alanine (BMAA), is present in stranded dolphins. BMAA has been shown to bioaccumulate in the marine food web, including in the muscles and fins of sharks. Dietary exposure to BMAA is associated with the occurrence of neurofibrillary tangles and β-amyloid plaques in nonhuman primates. The findings of protein-bound BMAA in brain tissues from patients with Alzheimer’s disease has advanced the hypothesis that BMAA may be linked to dementia. Since dolphins are apex predators and consume prey containing high amounts of BMAA, we examined necropsy specimens to determine if dietary and environmental exposures may result in the accumulation of BMAA in the brains of dolphins. To test this hypothesis, we measured BMAA in a series of brains collected from dolphins stranded in Florida and Massachusetts using two orthogonal analytical methods: 1) high performance liquid chromatography, and 2) ultra-performance liquid chromatography with tandem mass spectrometry. We detected high levels of BMAA (20–748 μg/g) in the brains of 13 of 14 dolphins. To correlate neuropathological changes with toxin exposure, gross and microscopic examinations were performed on cortical brain regions responsible for acoustico-motor navigation. We observed increased numbers of β-amyloid⁺ plaques and dystrophic neurites in the auditory cortex compared to the visual cortex and brainstem. The presence of BMAA and neuropathological changes in the stranded dolphin brain may help to further our understanding of cyanotoxin exposure and its potential impact on human health.

Classification and Genomic Diversity of Enterically Transmitted Hepatitis Viruses

Hepatitis A virus (HAV) and hepatitis E virus (HEV) are significant human pathogens and are responsible for a substantial proportion of cases of severe acute hepatitis worldwide. Genetically, both viruses are heterogeneous and are classified into several genotypes that differ in their geographical distribution and risk group association. There is, however, little evidence that variants of HAV or HEV differ antigenically or in their propensity to cause severe disease. Genetically more divergent but primarily hepatotropic variants of both HAV and HEV have been found in several mammalian species, those of HAV being classified into eight species within the genus Hepatovirus in the virus family Picornaviridae. HEV is classified as a member of the species Orthohepevirus A in the virus family Hepeviridae, a species that additionally contains viruses infecting pigs, rabbits, and a variety of other mammalian species. Other species (Orthohepevirus B-D) infect a wide range of other mammalian species including rodents and bats.

Molecular footprints of inshore aquatic adaptation in Indo-Pacific humpback dolphin (Sousa chinensis)

The Indo-Pacific humpback dolphin, Sousa chinensis, being a member of cetaceans, had fully adapted to inshore waters. As a threatened marine mammal, little molecular information available for understanding the genetic basis of ecological adaptation. We firstly sequenced and obtained the draft genome map of S. chinensis. Phylogenetic analysis in this study, based on the single copy orthologous genes of the draft genome, is consistent with traditional phylogenetic classification. The comparative genomic analysis indicated that S. chinensis had 494 species-specific gene families, which involved immune, DNA repair and sensory systems associated with the potential adaption mechanism. We also identified the expansion and positive selection genes in S. chinensis lineage to investigate the potential adaptation mechanism. Our study provided the potential insight into the molecular bases of ecological adaptation in Indo-Pacific humpback dolphin and will be also valuable for future understanding the ecological adaptation and evolution of cetaceans at the genomic level.

EASL Clinical Practice Guidelines on hepatitis E virus infection

Infection with hepatitis E virus (HEV) is a significant cause of morbidity and mortality, representing an important global health problem. Our understanding of HEV has changed completely over the past decade. Previously, HEV was thought to be limited to certain developing countries. We now know that HEV is endemic in most high-income countries and is largely a zoonotic infection. Given the paradigm shift in our understanding of zoonotic HEV and that locally acquired HEV is now the commonest cause of acute viral hepatitis in many European countries, the focus of these Clinical Practice Guidelines will be on HEV genotype 3 (and 4).

Challenges in research and management of hepatitis E virus infection in Cuba, Mexico, and Uruguay

The symposium "Epidemiology of Hepatitis E virus (HEV) Infection and Associated Immune Response" was held at the Universidad de Guadalajara, Mexico, on 14 June 2017, to define the status of research on HEV infection in three countries in Latin America and the Caribbean (LAC)-Cuba, Mexico, and Uruguay-compared to the situation in Germany. Scientists identified specific research gaps in understanding HEV transmission and the resulting impact on development of disease in the three abovementioned LAC countries. Specific recommendations for implementing standardized serologic and molecular diagnostic methods and epidemiologic, basic, and applied research aimed to develop prevention and handling strategies for this infection, along with the associated comorbidities in the three LAC countries, were also discussed. Given similar demographic, sanitary, and economic conditions in other LAC countries that could predispose them to be at high risk for HEV transmission and infection, these research gaps and recommendations might apply to the entire LAC region. This report was -prepared by meeting participants based on 1) symposium presentations, 2) literature reviews, and 3) group discussions.

Hepatitis E virus: advances and challenges

At least 20 million hepatitis E virus (HEV) infections occur annually, with >3 million symptomatic cases and ∼60,000 fatalities. Hepatitis E is generally self-limiting, with a case fatality rate of 0.5-3% in young adults. However, it can cause up to 30% mortality in pregnant women in the third trimester and can become chronic in immunocompromised individuals, such as those receiving organ transplants or chemotherapy and individuals with HIV infection. HEV is transmitted primarily via the faecal-oral route and was previously thought to be a public health concern only in developing countries. It is now also being frequently reported in industrialized countries, where it is transmitted zoonotically or through organ transplantation or blood transfusions. Although a vaccine for HEV has been developed, it is only licensed in China. Additionally, no effective, non-teratogenic and specific treatments against HEV infections are currently available. Although progress has been made in characterizing HEV biology, the scarcity of adequate experimental platforms has hampered further research. In this Review, we focus on providing an update on the HEV life cycle. We will further discuss existing cell culture and animal models and highlight platforms that have proven to be useful and/or are emerging for studying other hepatotropic (viral) pathogens.

Hepatitis E virus and related viruses in wild, domestic and zoo animals: A review

Hepatitis E is a human disease mainly characterized by acute liver illness, which is caused by infection with the hepatitis E virus (HEV). Large hepatitis E outbreaks have been described in developing countries; however, the disease is also increasingly recognized in industrialized countries. Mortality rates up to 25% have been described for pregnant women during outbreaks in developing countries. In addition, chronic disease courses could be observed in immunocompromised transplant patients. Whereas the HEV genotypes 1 and 2 are mainly confined to humans, genotypes 3 and 4 are also found in animals and can be zoonotically transmitted to humans. Domestic pig and wild boar represent the most important reservoirs for these genotypes. A distinct subtype of genotype 3 has been repeatedly detected in rabbits and a few human patients. Recently, HEV genotype 7 has been identified in dromedary camels and in an immunocompromised transplant patient. The reservoir animals get infected with HEV without showing any clinical symptoms. Besides these well-known animal reservoirs, HEV-specific antibodies and/or the genome of HEV or HEV-related viruses have also been detected in many other animal species, including primates, other mammals and birds. In particular, genotypes 3 and 4 infections are documented in many domestic, wildlife and zoo animal species. In most cases, the presence of HEV in these animals can be explained by spillover infections, but a risk of virus transmission through contact with humans cannot be excluded. This review gives a general overview on the transmission pathways of HEV to humans. It particularly focuses on reported serological and molecular evidence of infections in wild, domestic and zoo animals with HEV or HEV-related viruses. The role of these animals for transmission of HEV to humans and other animals is discussed.

Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.