Hepatitis E Seroprevalence and Genotyping in a Cohort of Wild Boars in Southern Germany and Eastern Alsace

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

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

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.

[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.

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.

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.

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.

High Seroprevalence of Hepatitis E Virus Infection Among East Balkan Swine (Sus scrofa) in Bulgaria: Preliminary Results

The East Balkan swine (Sus scrofa) is the only aboriginal pig breed in Bulgaria, and it is indigenous to the eastern part of the country. The aim of the present study was to investigate East Balkan swine (EBS) in Bulgaria for serological evidence of hepatitis E virus (HEV). Sera from 171 swine from two parts of the country (northeastern and southeastern) were tested for anti-HEV IgG antibodies. The overall HEV seroprevalence was 82.5% (141/171), and for weaners it was 77.2% (44/57), for fattening pigs 79.0% (45/57), and for adults 91.2% (52/57). HEV positivity was higher in fattening pigs and adults compared to weaners: OR = 1.108 (95% CI: 0.456–2.692) and OR = 3.073 (95% CI: 1.016–9.294), respectively. This study provides the first evidence of exposure to HEV in EBS from Bulgaria.

Increasing Hepatitis E Virus Seroprevalence in Domestic Pigs and Wild Boar in Bulgaria

Simple Summary

Hepatitis E virus (HEV) is a lesser-known hepatitis virus, but its worldwide spread is undisputed and has increased in recent years. The zoonotic spread of HEV, mainly due to genotype (gt) 3, emerged in developed countries in the past decade. In addition, transmission via contaminated meat from pigs and boars was also established. Detailed analysis of viral dynamics and distribution is needed in order to identify associated risk factors. The aim of the current study is to present new and additional data on the HEV distribution among pigs, and for the first-time, also among the wild boar population in Bulgaria.

Abstract

(1) Background: Hepatitis E virus (HEV) is a causative agent of acute viral hepatitis, predominantly transmitted by the fecal–oral route. In developed countries, HEV is considered to be an emerging pathogen since the number of autochthonous cases is rising. Hepatitis E is a viral disease with a proven zoonotic potential for some of its genotypes. The main viral reservoirs are domestic pigs and wild boar. Consumption of undercooked meat, as well as occupational exposure, are key factors for the spread of HEV. In order to evaluate the risks of future viral evolution, a detailed examination of the ecology and distribution of the virus is needed. The aim of the present study is to investigate the prevalence of anti-HEV IgG Ab in domestic pigs and wild boar in Bulgaria; (2) Methods: In this study, during the period of three years between 2017 and 2019, 433 serum samples from 19 different pig farms and 1 slaughterhouse were collected and analyzed. In addition, 32 samples from wild boar were also collected and analyzed during the 2018–2019 hunting season. All samples were analyzed by commercial indirect ELISA; (3) Results: Overall, HEV seroprevalence was 60% (95% CI 42.7–77.1) in domestic pigs and 12.5% (4/32) in wild boar. The observed seroprevalence of the slaughter-aged pigs was 73.65% (95% Cl 58.7–87.3). Prevalence in domestic pigs was significantly higher in the samples collected during 2019 (98% (95% Cl 96.1–99.9)) compared to those collected during 2017 (45.33% (95% CI 2.7–87.3)) and 2018 (38.46% (95% CI 29.1–49.7.); (4) Conclusions: Our findings suggest that domesticated pigs and wild boar might be the reason for the increased HEV transmission across Bulgaria. The genotypic characterization of HEV found in pigs, wild boar and humans will give a more accurate view of the zoonotic transmission of this virus.

Screening and Molecular Characterization of Hepatitis E Virus in Slaughter Pigs in Serbia

Hepatitis E virus (HEV) is a zoonotic virus that can cause acute hepatitis in humans. Besides the fecal-oral route, transmission can occur by consumption of undercooked pig liver. Genotype 3 is the most frequent genotype found in Europe. Studies on HEV in slaughter-age pigs have not been conducted in Serbia so far. Pork meat production and consumption in Serbia is on average, higher than in the rest of Europe. With the aim to identify the circulating HEV genotypes, pig livers and swab samples from three pig slaughterhouses located in three different sub-regions of Serbia were collected. A nested RT-PCR was used to amplify the hypervariable HEV ORF-1 region (334 bp). The amplicons yielded in this study were sequenced, and a molecular phylogeny analysis based on the maximum likelihood method, including HEV sequences reported in several other countries, was performed. The average prevalence of HEV genotype 3 in 3-month-old pigs was 34%. Phylogenetic analysis revealed the majority of HEV amplification fragments from Serbia were grouped in four clades within sub-genotype 3a and were also genetically related to German, Italian, Slovenian, and American HEV sequences. Sub-genotypes 3b and 3j were also found in a single pig each. This study provides the first analysis of the genetic diversity and circulation dynamics of HEV in pigs at slaughterhouses in Serbia.

Emergent subtype of hepatitis E virus genotype 3 in wild boar in Spain

Wild boar (Sus scrofa) is considered as the main wildlife reservoir of zoonotic hepatitis E virus (HEV) genotypes. The aim of this study was to evaluate the circulation of HEV in free-ranging wild boar in the Doñana National Park (DNP), Spain. Blood samples were collected from 99 wild boar in the DNP during 2015. Sera were analysed in parallel using indirect ELISA and real-time RT-PCR. A total of 57 of the 99 tested animals (57.6%; 95%CI: 47.8%-67.3%) had anti-HEV antibodies, indicating that this virus is widespread in wild boar in the DNP. HEV RNA was detected in one animal and phylogenetic analysis showed that the sequence isolated belonged to subtype 3r. The results suggest a potential risk of zoonotic transmission of this novel HEV-3 subtype, which could be of public health concern. Further studies are required to assess the role of wild boar in the epidemiology of HEV-3r and to determine the infectivity of this emergent HEV subtype in other species, including humans.

Wild Boar: A Reservoir of Foodborne Zoonoses

Wild boar populations around the world have increased dramatically over past decades. Climate change, generating milder winters with less snow, may affect their spread into northern regions. Wild boars can serve as reservoirs for a number of bacteria, viruses, and parasites, which are transmissible to humans and domestic animals through direct interaction with wild boars, through contaminated food or indirectly through contaminated environment. Disease transmission between wild boars, domestic animals, and humans is an increasing threat to human and animal health, especially in areas with high wild boar densities. This article reviews important foodborne zoonoses, including bacterial diseases (brucellosis, salmonellosis, tuberculosis, and yersiniosis), parasitic diseases (toxoplasmosis and trichinellosis), and the viral hepatitis E. The focus is on the prevalence of these diseases and the causative microbes in wild boars. The role of wild boars in transmitting these pathogens to humans and livestock is also briefly discussed.

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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