Molecular epidemiology of hepatitis E virus in humans, pigs and wild boars in Sweden

SUMMARYHepatitis E infections in humans are usually acquired in endemic countries in Asia or Africa. In Sweden 17 cases infected in Europe, between 1993 and 2009, were identified. All had clinical hepatitis E with unknown source of infection. Hepatitis E virus (HEV) was identified in faecal samples from 63 piglets in 12 pig farms in Sweden. HEV was also identified in blood from 13 out of 159 investigated Swedish wild boars from nine counties. Partial HEV genomes from humans, pigs and wild boars were sequenced and compared by phylogeny. The results showed close relatedness between HEV strains from piglets from the same farm and from wild boars from the same county. HEV strains from humans showed relatedness with strains from pigs and wild boars from the same county. This study showed that HEV strains form geographical clusters in the phylogenetic tree. The methods used in this study may thus be used for tracing the origin of an infecting strain. Furthermore, this study indicated that there are endemic sources of human HEV infections in Sweden.

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Viral hepatitis E: A disease of humans and animals

Veterinarski glasnik ◽

10.2298/vetgl1206449k ◽

2012 ◽

Vol 66 (5-6) ◽

pp. 449-462

Author(s):

Branislav Kureljusic ◽

Vojin Ivetic ◽

Bozidar Savic ◽

Jasna Kureljusic ◽

Nemanja Jezdimirovic

Keyword(s):

Viral Hepatitis ◽

Hepatitis E Virus ◽

Clinical Signs ◽

Hepatitis E ◽

Developed Countries ◽

Animal Origin ◽

Oral Transmission ◽

Source Of Infection ◽

Pig Farms ◽

The Usa

The hepatitis E virus is ubiquitous in all parts of the world where pig production exists. The infection occurs in several animal species and its course is mostly asymptomatic. Viral strains isolated from pigs and humans are genetically similar, which indicates a potential zoonotic nature of the disease, and the possibility that pigs, and perhaps also other species of animals diseased with viral hepatitis E are a source of infection to humans. The pig hepatitis E virus, which is similar to the hepatitis E virus in humans, was isolated and described for the first time in the USA in 1997. The infection of pigs with hepatitis E virus occurs through faeco-oral transmission, by ingestion of feed and water contaminated with the virus, or through direct contact between infected and healthy animals. The pathogenesis of this infection in pigs differs from its pathogenesis in humans and it has not been sufficiently examined in all its aspects. Even though viral hepatitis E in pigs has been described as a subclinical disease, some authors describe changes in the concentration of certain biochemical parameters in blood serum of the infected pigs. Histologically, a mild to moderate lymphotic-plasma cellular infiltration is observed in livers of infected pigs, as well as focal areas of hepatocyte necrosis. Viral hepatitis E is an endemic disease of humans in Asia, Africa, and Latin America. In developed countries, hepatitis E sporadically occurs in humans, but it is becoming of increasing importance in particular in Japan, North America, and Europe, because the populations of these areas travel extensively to the endemic regions or as a result of the consumption of thermally untreated meat of wild boar and products made from thermally untreated meat. Pork products can be contaminated with hepatitis E virus. Further proof that indicates the zoonotic potential of this virus and places this diseases among the group of professional diseases of farmers and veterinarians is the finding of antibodies to hepatitis E virus in farmers and veterinarians who work on pig farms without showing any clinical signs of the disease. Having in mind the fact that viral hepatitis E has been proven in pig farms in Serbia and neighboruign countries, there should be strict respect of biosecutiry measures from the episootiological and epidemiological aspects, and the principle of good production and hygiene practice should be adhered to on pig farms. This disease should in future also be included in the legal regulations of our country in order to ensure the production of products of animal origin that are safe from the aspect of hygiene.

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Wild Boar as a Sylvatic Reservoir of Hepatitis E Virus in Poland: A Cross-Sectional Population Study

Viruses ◽

10.3390/v12101113 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1113

Author(s):

Iwona Kozyra ◽

Artur Jabłoński ◽

Ewelina Bigoraj ◽

Artur Rzeżutka

Keyword(s):

Wild Boar ◽

Regional Differences ◽

Hepatitis E Virus ◽

Hepatitis E ◽

Igg Antibodies ◽

Cross Sectional ◽

Wild Boars ◽

Wildlife Species ◽

Faecal Samples ◽

Molecular Assessment

The most important wildlife species in the epidemiology of hepatitis E virus (HEV) infections are wild boars, which are also the main reservoir of the virus in a sylvatic environment. The aim of the study was a serological and molecular assessment of the prevalence of HEV infections in wild boars in Poland. In total, 470 pairs of samples (wild boar blood and livers) and 433 samples of faeces were tested. An ELISA (ID.vet, France) was used for serological analysis. For the detection of HEV RNA, real-time (RT)-qPCR was employed. The presence of specific anti-HEV IgG antibodies was found in 232 (49.4%; 95%CI: 44.7–54%) sera, with regional differences observed in the seroprevalence of infections. HEV RNA was detected in 57 (12.1%, 95%CI: 9.3–15.4%) livers and in 27 (6.2%, 95%CI: 4.1–8.9%) faecal samples, with the viral load ranging from 1.4 to 1.7 × 1011 G.C./g and 38 to 9.3 × 107 G.C./mL, respectively. A correlation between serological and molecular results of testing of wild boars infected with HEV was shown. HEV infections in wild boars appeared to be common in Poland.

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Infection dynamics and persistence of hepatitis E virus on pig farms – a review

Porcine Health Management ◽

10.1186/s40813-021-00189-z ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

M. Meester ◽

T. J. Tobias ◽

M. Bouwknegt ◽

N. E. Kusters ◽

J. A. Stegeman ◽

...

Keyword(s):

Risk Factors ◽

Hepatitis E Virus ◽

Risk Mitigation ◽

Transmission Rate ◽

Hepatitis E ◽

Main Body ◽

Genotype 3 ◽

Infection Dynamics ◽

Pig Farms ◽

Slaughter Pigs

Abstract Background Hepatitis E virus (HEV) genotype 3 and 4 is a zoonosis that causes hepatitis in humans. Humans can become infected by consumption of pork or contact with pigs. Pigs are the main reservoir of the virus worldwide and the virus is present on most pig farms. Main body Though HEV is present on most farms, the proportion of infected pigs at slaughter and thus the level of exposure to consumers differs between farms and countries. Understanding the cause of that difference is necessary to install effective measures to lower HEV in pigs at slaughter. Here, HEV studies are reviewed that include infection dynamics of HEV in pigs and on farms, risk factors for HEV farm prevalence, and that describe mechanisms and sources that could generate persistence on farms. Most pigs become infected after maternal immunity has waned, at the end of the nursing or beginning of the fattening phase. Risk factors increasing the likelihood of a high farm prevalence or proportion of actively infected slaughter pigs comprise of factors such as farm demographics, internal and external biosecurity and immunomodulating coinfections. On-farm persistence of HEV is plausible, because of a high transmission rate and a constant influx of susceptible pigs. Environmental sources of HEV that enhance persistence are contaminated manure storages, water and fomites. Conclusion As HEV is persistently present on most pig farms, current risk mitigation should focus on lowering transmission within farms, especially between farm compartments. Yet, one should be aware of the paradox of increasing the proportion of actively infected pigs at slaughter by reducing transmission insufficiently. Vaccination of pigs may aid HEV control in the future.

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

Virology Journal ◽

10.1186/s12985-021-01626-9 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Fufa Dawo Bari ◽

Haimanot Belete Wodaje ◽

Umer Said ◽

Hika Waktole ◽

Melaku Sombo ◽

...

Keyword(s):

Public Health ◽

Hepatitis E Virus ◽

Addis Ababa ◽

Hepatitis E ◽

Human Infection ◽

Health Concern ◽

Universal Primers ◽

Viral Gene ◽

Public Health Importance ◽

Faecal Samples

Abstract 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.

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Seroprevalence of Hepatitis E Virus Infection among Blood Donors in Bulgaria

Viruses ◽

10.3390/v13030492 ◽

2021 ◽

Vol 13 (3) ◽

pp. 492

Author(s):

Magdalena Baymakova ◽

Krasimira Terzieva ◽

Rumen Popov ◽

Elisaveta Grancharova ◽

Todor Kundurzhiev ◽

...

Keyword(s):

Virus Infection ◽

Hepatitis E Virus ◽

Blood Donors ◽

Hepatitis E ◽

Elisa Test ◽

Blood Samples ◽

Wild Boars ◽

Domestic Pigs ◽

Specific Questionnaire ◽

Positive Results

Hepatitis E virus (HEV) infection is widespread among domestic pigs, industrial swine, and wild boars in Bulgaria. The aim of the current research was to present the HEV seroprevalence among blood donors in Bulgaria. In the present study, 555 blood donors (479 males and 76 females) were enrolled from five districts in the country (Shumen, Pleven, Stara Zagora, Plovdiv, and Sofia districts). All blood samples were tested for anti-HEV IgG using the recomWell HEV IgG ELISA test (Mikrogen GmbH, Neuried, Germany). Each participating donor completed a short, structured, and specific questionnaire to document data on the current study. Anti-HEV IgG positive results were detected in 144 (25.9%) blood donors, including 129 (26.9%) males and 15 (19.7%) females. The established HEV seropositivity was 28.8% (23/80) in Shumen district, 23.2% (22/95) in Pleven district, 27.1% (38/140) in Stara Zagora district, 27.5% (44/160) in Plovdiv district, and 21.3% (17/80) in Sofia district. A high HEV seroprevalence was found for persons who declared that they were general hunters (48.7%; 19/39; p = 0.001) and hunters of wild boars (51.6%; 16/31; p = 0.001). We present the first seroprevalence rates of HEV infection in blood donors from Bulgaria. The results of our research showed high HEV seropositivity among blood donors.

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Cell Culture Isolation and Whole Genome Characterization of Hepatitis E Virus Strains from Wild Boars in Germany

Microorganisms ◽

10.3390/microorganisms9112302 ◽

2021 ◽

Vol 9 (11) ◽

pp. 2302

Author(s):

Katja Schilling-Loeffler ◽

Oliver Viera-Segura ◽

Victor Max Corman ◽

Julia Schneider ◽

Ashish K. Gadicherla ◽

...

Keyword(s):

Cell Culture ◽

Wild Boar ◽

Hepatitis E Virus ◽

Hepatitis E ◽

Enriched Library ◽

Genome Copy ◽

Genotype 3 ◽

Wild Boars ◽

Copy Numbers ◽

Cell Culture Isolation

Infection with hepatitis E virus (HEV) can cause acute and chronic hepatitis in humans. The HEV genotype 3 can be zoonotically transmitted from animals to humans, with wild boars representing an important reservoir species. Cell culture isolation of HEV is generally difficult and mainly described for human isolates so far. Here, five sera and five liver samples from HEV-RNA-positive wild boar samples were inoculated onto PLC/PRF/5 cells, incubated for 3 months and thereafter passaged for additional 6 weeks. As demonstrated by RT-qPCR, immunofluorescence and immune electron microscopy, virus was successfully isolated from two liver samples, which originally contained high HEV genome copy numbers. Both isolates showed slower growth than the culture-adapted HEV strain 47832c. In contrast to this strain, the isolated strains had no insertions in their hypervariable genome region. Next generation sequencing using an HEV sequence-enriched library enabled full genome sequencing. Strain Wb108/17 belongs to subtype 3f and strain Wb257/17 to a tentative novel subtype recently described in Italian wild boars. The results indicate that HEV can be successfully isolated in cell culture from wild boar samples containing high HEV genome copy numbers. The isolates may be used further to study the zoonotic potential of wild boar-derived HEV subtypes.

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