Hepatitis E Virus of Subtype 3a in a Pig Farm, South-Eastern France

Hepatitis E Virus in Livestock-Update on Its Epidemiology and Risk of Infection to Humans

Hepatitis E virus (HEV) is a public health problem worldwide and an important food pathogen known for its zoonotic potential. Increasing numbers of infection cases with human HEV are caused by the zoonotic transmission of genotypes 3 and 4, mainly by consuming contaminated, undercooked or raw porcine meat. Pigs are the main reservoir of HEV. However, it should be noted that other animal species, such as cattle, sheep, goats, and rabbits, may also be a source of infection for humans. Due to the detection of HEV RNA in the milk and tissues of cattle, the consumption of infected uncooked milk and meat or offal from these species also poses a potential risk of zoonotic HEV infections. Poultry infected by avian HEV may also develop symptomatic disease, although avian HEV is not considered a zoonotic pathogen. HEV infection has a worldwide distribution with different prevalence rates depending on the affected animal species, sampling region, or breeding system.

Detection of zoonotic pathogens in animals performed at the University Hospital Institute Méditerranée Infection (Marseille - France)

At the University Hospital Institute Méditerranée Infection (IHU, Marseille, France), for almost thirty years, veterinarians have been carrying out epidemiological investigations, together with doctors, on animals living near human cases of zoonoses, on the one hand, and on the other hand, transverse and longitudinal epidemiological surveillance studies on animals which are reservoirs, vectors or sentinels of potentially zoonotic infections,. This article presents the methods adopted and the results obtained from these studies. They have been the subject of 76 peer-reviewed publications relating to wild animals (37 publications) and/or domestic animals (48 publications). These studies were often carried out in the field with veterinarians from the French army's health service (39 publications). They were at the origin of the detection of some thirty zoonotic pathogens in the laboratories of the IHU (64 publications) and/or other French laboratories (18 publications). Our approach is an original embodiment of the "One Health" concept.

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

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.

Patterns of mutation within an emerging endemic lineage of HEV-3a

The hepatitis E virus can cause chronic infections in immuno-suppressed patients, and cases have been on the rise globally. Viral mutations during such infections are difficult to characterize. We deep-sequenced viral populations from 15 immunocompromised patients with chronic HEV to identify the viral lineage and describe viral mutational hotspots within and across patients. A total of 21 viral RNA samples were collected between 2012 and 2017 from a single hospital in Singapore. Sequences covering a total of 3894 bp of the HEV genome were obtained. Phylogenetic analyses identified all sequences as belonging to the HEV-3a sub-clade and clearly indicate a unique local lineage. Deep sequencing reveals variable viral population complexity during infections. Comparisons of viral samples from the same patients spaced 2-19 months apart revealed rapid nucleotide replacements in the dominant viral sequence in both ribavirin treated and treatment-naive patients. Mutational hotspots were identified within ORF3 and the PCP/HVR domain of ORF1.

Investigations by the Institut Hospitalo-Universitaire Méditerranée Infection of food and food-borne infections in the Mediterranean Basin and in sub-Saharan Africa

Food-borne infections are major causes of public health concern in developing and developed countries. During the past decade, the Institut Hospitalo-Universitaire Méditerranée Infection has conducted or been involved in multiple investigations that aimed at identifying the sources and strains responsible for food-borne diseases and therefore at improving the understanding, diagnosis, prevention and control of these infections. Investigations were conducted in the Mediterranean area and in sub-Saharan Africa on more than 15 food-borne agents, 17 food products and 14 antibiotic resistance-associated genes. Multiple sources, including unexpected ones, and pathogens, including emerging ones, were involved. Travelling in developing countries and zoonoses are major contributors to food-borne infections, while food-borne transmission of resistance-associated genes is increasingly reported. However, risk factors and pathogens associated with food-borne infections likely remain untapped and must be more extensively investigated, monitored and regularly reassessed. Diagnostic tests based on new technologies and real-time surveillance tools based on microbiology laboratory data are promising approaches to detect known food-borne infections and decipher new ones. Studies of the microbiota and its relationships with dietary patterns are also worth being conducted.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Hepatic rupture hemorrhage syndrome in chickens caused by a novel genotype avian hepatitis E virus

Since 2016, severe outbreaks of hepatic rupture hemorrhage syndrome (HRHS) have emerged in chickens in several Chinese provinces and caused huge economic losses to the poultry industry, but the etiological characteristics and pathogenic potential of it has remained unclear. This study sequenced the partial helicase and capsid gene of the potentially novel avian hepatitis E virus (HEV) isolated from chickens with HRHS and tested the pathogenicity of it on SPF chicks, while the appearance of clinical signs, histopathological changes, viral distribution, viremia and viral shedding were monitored for 14 days post-infection (dpi). Analysis revealed that the HRHS related avian HEV belongs to a novel genotype, and infected chicks developed the typical symptoms of HRHS. Thus, this study successfully developed an experimental infection model for studying the pathogenicity and role of the novel avian HEV in HRHS. Meanwhile, the novel avian HEV mainly existed in the liver and spleen, inducing a rapid viremia and chronic viral shedding in infected chicks, and could cause 40% mortality before 14 dpi. In conclusion, this study found the novel genotype avian HEV and confirmed its role in HRHS.

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.

Autochthonous infection with hepatitis E virus related to subtype 3a, France: a case report

Hepatitis E virus (HEV) recently emerged in Europe as a cause of autochthonous acute hepatitis and a porcine zoonosis. European autochthonous cases almost exclusively involved viruses of genotype 3, subtype 3a being only recently reported in France, from farm pigs. We report an autochthonous human infection with a HEV related to subtype 3a in Southeastern France. A 55-year-old human immunodeficiency virus-infected man presented liver cytolysis in June 2014. HEV RNA was detected in serum and three months later, anti-HEV IgM and IgG were positive whereas HEV RNA was no more detectable in serum. No biological or clinical complication did occur. HEV phylogeny based on two capsid gene fragments showed clustering of sequences obtained from the case-patient with HEV-3a, mean nucleotide identity being 91.7 and 91.3% with their 10 best GenBank matches that were obtained in Japan, South Korea, USA, Canada, Germany and Hungria from humans, pigs and a mongoose. Identity between HEV sequence obtained here and HEV-3a sequences obtained at our laboratory from farm pigs sampled in 2012 in Southeastern France was only 90.2-91.4%. Apart from these pig sequences, best hits from France were of subtypes 3i, 3f, or undefined. The patient consumed barely cooked wild-boar meat; no other risk factor for HEV infection was documented. In Europe, HEV-3a has been described in humans in England and Portugal, in wild boars in Germany, and in pigs in Germany, the Netherlands, and, recently, France. These findings suggest to gain a better knowledge of HEV-3a circulation in France.

Incidence and Molecular Characterization of Hepatitis E Virus from Swine in Eastern Cape, South Africa

Hepatitis E virus-mediated infection is a serious public health concern in economically developing nations of the world. Globally, four major genotypes of HEV have been documented. Hepatitis E has been suggested to be zoonotic owing to the increase of evidence through various studies. Thus far, this paper reports on prevalence of hepatitis E virus among swine herd in selected communal and commercial farms in the Eastern Cape Province of South Africa. A total of 160 faecal samples were collected from swine herds in Amathole and Chris Hani District Municipalities of Eastern Cape Province for the presence of HEV. Of the 160 faecal samples screened, only seven were positive (4.4%) for HEV. The nucleotide sequences analyses revealed the isolates as sharing 82% to 99% identities with other strains (KX896664, KX896665, KX896666, KX896667, KX896668, KX896669, and KX896670) from different regions of the world. We conclude that HEV is present among swine in the Eastern Cape Province, albeit in low incidence, and this does have public health implications. There is a need for maintenance of high hygienic standards in order to prevent human infections through swine faecal materials and appropriate cooking of pork is highly advised.