Frequent transmission of hepatitis E virus among piglets in farms in Southern France

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.

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.

Real-Time PCR-Based Methods for Detection of Hepatitis E Virus in Pork Products: A Critical Review

Standard methods for detection of hepatitis A virus and norovirus in at-risk foodstuffs are available, but currently there is no standard method for detection of hepatitis E virus (HEV) in pork products or other foods that can be contaminated with the virus. Detection assays for HEV are mainly based on nucleic acid amplification, particularly the reverse transcription polymerase chain reaction (RTPCR) in real-time format. RTPCR-based methods can be sensitive and specific, but they require a suite of controls to verify that they have performed correctly. There have been several RTPCR methods developed to detect HEV in pork products, varying in details of sample preparation and RTPCR target sequences. This review critically discusses published HEV detection methods, with emphasis on those that have been successfully used in subsequent studies and surveys. RTPCR assays have been used both qualitatively and quantitatively, although in the latter case the data acquired are only reliable if appropriate assay calibration has been performed. One particular RTPCR assay appears to be ideal for incorporation in a standard method, as it has been demonstrated to be highly specific and sensitive, and an appropriate control and calibration standard is available. The review focuses on the detection of HEV in pork products and similar foodstuffs (e.g., boar). The information may be useful to inform standardisation activities.

Clinical significance of post-liver transplant hepatitis E seropositivity in high prevalence area of hepatitis E genotype 3: a prospective study

High hepatitis E (HEV) seroprevalence has been reported in the general population and in post-liver transplant (LT) cases in several regions, including Thailand, with genotype 3 being a predominant genotype. We hypothesized that HEV might persist at a subclinical level and might pose clinical risks in the post-LT period. We performed a cross-sectional study with 108 post-LT patients and found an IgG seroprevalence of 55.6%. Subsequently, 91 cases without clinical evidence of HEV-related hepatitis were enrolled in 1 year of prospective follow-up to determine clinical status, serologies and serum/feces HEV RNA every 4 months. HEV RNA was detected, indicating subclinical infections in patients with or without seropositivity, with an annual incidence of 7.7%. Our results suggest that subclinical HEV infection exists among LT patients in this high-prevalence area. Thus, clinicians should be aware of the possibility of disease reemergence and HEV viral transmission in LT patients.

Hepatitis E virus strains infecting Swedish domestic pigs are unique for each pig farm and remain in the farm for at least 2 years

Hepatitis E virus (HEV) genotype 3 (HEV3) is distributed globally and infects both humans and animals, mainly domestic pigs and wild boars, which are the major reservoirs. In this study, the prevalence of HEV among Swedish pigs was investigated by HEV RNA analysis in 363 faecal samples from 3-month-old piglets sampled twice (2013 and 2014) in 30 Swedish pig farms. Four different types of farms were investigated; organic, conventional closed (keeping the sow), satellites in a sow pool (conventional farms sharing sows) and conventional non-closed farms (purchasing gilts). More than two-thirds (77%) of the farms had HEV-infected pigs. HEV RNA was found in faeces from 79 pigs (22%). Partial ORF1 could be sequenced in 46 strains. Phylogenetic analysis revealed a unique HEV3 strain for each farm. Strains sampled more than a year apart from the same farm were closely related, indicating that the same HEV strain is present for several years on the farm. Despite that only 4% of the Swedish pig farms were investigated, two farms had strains similar to those from humans, another had strains similar to wild boar HEV. The uniqueness of strains from each farm indicates a possibility to identify a source of infection down to farm level. This knowledge may be used by the farms to investigate the effectiveness of good hygiene routines to reduce the amount of HEV and thus the infection risk in the farm, and for Swedish public health authorities to identify cases of HEV transmissions from consumption of uncooked pork.

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.

Risk Analysis and Occurrence of Hepatitis E Virus (HEV) in Domestic Swine in Northeast Brazil

Anti-HEV antibodies were detected in animals from abattoir and in farms from northeast Brazil. Our results suggest that HEV is highly disseminated in the swine population and might present a great risk to animal handlers and for consumption of raw or undercooked meat and meat products in northeast Brazil.

From the epidemiology of hepatitis E virus (HEV) within the swine reservoir to public health risk mitigation strategies: a comprehensive review

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mainly transmitted via food in developed countries and for which domestic pigs are recognised as the main reservoir. It therefore appears important to understand the features and drivers of HEV infection dynamics on pig farms in order to implement HEV surveillance programmes and to assess and manage public health risks. The authors have reviewed the international scientific literature on the epidemiological characteristics of HEV in swine populations. Although prevalence estimates differed greatly from one study to another, all consistently reported high variability between farms, suggesting the existence of multifactorial conditions related to infection and within-farm transmission of the virus. Longitudinal studies and experimental trials have provided estimates of epidemiological parameters governing the transmission process (e.g. age at infection, transmission parameters, shedding period duration or lag time before the onset of an immune response). Farming practices, passive immunity and co-infection with immunosuppressive agents were identified as the main factors influencing HEV infection dynamics, but further investigations are needed to clarify the different HEV infection patterns observed in pig herds as well as HEV transmission between farms. Relevant surveillance programmes and control measures from farm to fork also have to be fostered to reduce the prevalence of contaminated pork products entering the food chain.

Seroepidemiology and molecular characterization of hepatitis E virus infection in swine and occupationally exposed workers in Punjab, India

Hepatitis E virus (HEV) has two discrete epidemiological patterns: waterborne epidemics in developing countries only, caused by HEV genotype I, and sporadic zoonotic outbreaks in developing and developed countries caused by genotypes III and IV. This study was designed to investigate seroprevalence, molecular detection and the characterization of HEV by nested RT-PCR in swine as well as the occupational risk to exposed human population in Punjab state of north-western India. The occupational risk-exposed group comprised of swine farmers (organized - mixed feed feeders and unorganized - swill feeders), slaughterhouse workers, sewage workers and veterinary internes. During the study period, blood and faecal samples were collected from 320 swine and 360 humans with both high and low occupational exposure risks. The overall seroprevalence of swine HEV was 65.00%, with a significantly higher seropositivity in growing pigs (2-8 months of age). The prevalence of HEV RNA in swine faecal samples by nRT-PCR was 8.75% with a significantly higher detection in swill-fed pigs. With humans in the high occupational exposure risk population, significantly higher anti-HEV IgG seropositivity was observed (60.48%) as compared to control population (10.71%). Strong evidence of association between human anti-HEV IgG seropositivity and certain occupational exposure risk groups was observed (p < 0.05). This indicates that unorganized swine farmers, slaughterhouse workers and sewage workers have higher odds of HEV infection in this study region. Percentage of nucleotide similarity between swine and human HEV isolates was less than that found in countries with zoonotic HEV outbreaks. Molecular characterization revealed the circulation of G IV and G I genotypes among swine and human population in Punjab state, respectively.

Hepatitis E virus in wild rabbits and European brown hares in Germany

Recently, a change of hepatitis E from being a typical travel-associated disease to an autochthonous zoonosis in Germany was observed. An increasing number of autochthonous infections with the hepatitis E Virus (HEV) have been recognized in developed countries. Venison from wild boar is already known to be a potential source of infection, if not prepared properly by the consumer. In Germany, certain wild animals are known to be a reservoir for HEV. However, current information is missing about European brown hares (Lepus europaeus) and wild rabbits (Oryctolagus cuniculus). Thus, a total of 833 hunting-harvested animals (European brown hares n = 669; wild rabbits n = 164) were tested for the occurrence of HEV RNA and HEV antibodies. For this, liver and blood specimens were taken after hunts in six German federal states. HEV antibodies were found by ELISA in 2.2% (624/14) of European brown hares, but no HEV RNA was detectable by nested real-time RT-PCR. In contrast, a seroprevalence of 37.3% (126/47) was observed for wild rabbits, and 17.1% (164/28) of the samples were HEV RNA positive. Genomic analysis revealed that these partial sequences clustered within the rabbit clade of HEV-3 genotype. In addition, one rabbit sequence segregated into subtype 3g of HEV-3. Highest seroprevalences for hares and rabbits were detected in the federal states of Bavaria and of Schleswig-Holstein, respectively. Comparing urban, rural and insular areas, the highest seroprevalence was shown for wild rabbits in rural areas and for European brown hares on the northern island Fehmarn. This study provides evidence that European brown hares and wild rabbits from Germany can be infected with HEV. The different prevalences indicate that wild rabbits are a potential reservoir for HEV in Germany, whereas European brown hares seem to be only of minor importance for the epidemiology of HEV.

Hepatitis E Virus in Pork and Variety Meats Sold in Fresh Markets

Swine is an economically important livestock, yet pork consumption and close contact with pigs are associated with the risk of hepatitis E virus (HEV) infection. Limited data on the prevalence of HEV in Southeast Asia have mainly examined farm animals. To investigate the potential zoonotic transmission of HEV from dietary consumption of pork and variety meats (i.e., offal or organ meats), we obtained 1090 liver, 559 pork meat, and 556 intestine samples from fresh markets in the Bangkok metropolitan area between November 2014 and February 2015. The presence of HEV was assessed using reverse-transcription polymerase chain reaction. Concurrently, 720 bile and 553 fecal samples from a slaughterhouse were also examined. Overall, HEV RNA was found in 0.23 % of the market samples and 3.93 % of the slaughterhouse samples. Fecal and bile samples were more likely to test positive compared to liver, pork, and intestine samples (p < 0.001). Phylogenetic analysis showed that all HEV sequences obtained in this study formed a cluster closely related to genotype 3f. Pork and variety meats derived from pigs are commonly sold in fresh markets throughout Southeast Asia. Here, a relatively low HEV prevalence from pork and variety meats sold in Bangkok was found. Additional studies will be required to further assess potential dietary transmission of HEV elsewhere in the region.

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

Hepatitis E virus (HEV) has emerged during the past decade as a causative agent of autochthonous hepatitis and is a clinical concern in Western developed countries. It has been increasingly recognized that pigs are a major reservoir of HEV of genotypes 3 and 4 worldwide and pig-derived food items represent a potential source of infections by these viruses in humans. Hepatitis E virus RNA testing was performed here on faeces from rectal swabs sampled in 2012 from 50 3-month-old farm pigs from the same farm located in south-eastern France than in a previous work conducted in 2007. Pig HEV sequences corresponding to genomic fragments of ORF2 and ORF1 genes were obtained after RT-PCR amplification with in-house protocols. Hepatitis E virus genotype was determined by phylogenetic analysis. Prevalence was similar to that determined 5 years earlier (68% versus 62%). Two robust phylogenetic clusters of HEV subtypes 3a and 3f were identified, and these sequences obtained in 2012 largely differ compared with those obtained in 2007. Notably, HEV sequences obtained in 2012 from a majority (62%) of the infected pigs belonged to subtype 3a, which was not previously described in France, including not being found in any of humans, pigs or wild boars. Further studies are needed to assess the circulation of HEV-3a in pigs and humans in this country. In addition, along with previous findings, this study supports the need for increased information to the public on the risk of HEV infection through contacts with pigs or consumption of pig-derived products in France.

Systematic serological testing for hepatitis E virus in kidney transplant recipients

Hepatitis E virus (HEV) genotype 3 is endemic in Europe and hyperendemic in southern France. Recent reports of a high prevalence of HEV RNA in blood donations and in culinary specialties from this geographical area confirmed the endemicity of HEV and sources of viral transmission in this geographical area. HEV causes acute and chronic hepatitis in solid organ transplant recipients. Since March 2012, we have implemented systematic HEV serological testing in our cohort of kidney transplant recipients (KTRs) in Marseille in southeastern France. The aim of our study was to assess HEV exposure in this cohort between March 2012 and May 2014. During these 27 months, we found that 39% of the patients who underwent kidney transplantation had an anti-HEV IgG response using a sensitive microplate enzyme immunoassay. This seroprevalence was approximately 43% at both 1 and 8 years after, using the same assay. In addition, systematic HEV serological testing detected 6 cases of HEV infection among 578 KTRs (1%) during the 27 months of the study, with 5 at an acute stage and 1 at a chronic stage. In conclusion, continuous HEV monitoring in this population is useful for better understanding the epidemiology of HEV in France, because these patients are a well-monitored population. Moreover, HEV monitoring in KTRs is clinically relevant because HEV represents a clinical threat in these patients. Nevertheless, HEV serological testing may be more fruitful for identifying HEV infections when performed in cases of biological liver abnormalities than when performed systematically.

Seroprevalence and molecular characteristics of hepatitis E virus in household-raised pig population in the Philippines

Background

Hepatitis E virus (HEV) infection is a significant public health concern in Asia, and swine is an important source of sporadic HEV infection in human. However, no epidemiological data are available regarding HEV infection among the swine or human population in the Philippines. To assess the HEV infection status among pigs in rural areas, we investigated the molecular characteristics and seroprevalence of HEV among household-raised pigs in San Jose, Tarlac Province, the Philippines.

Result

Serum and rectal swab samples were collected from 299 pigs aged 2–24 months from 155 households in four barangays (villages) between July 2010 and June 2011. Enzyme-linked immunosorbent assay (ELISA) revealed that 50.3% [95% confidence interval (CI) 44.5–56.2%] and 22.9% (95% CI 18.2–28.1%) of pigs tested positive for anti-HEV IgG and IgM, respectively. HEV RNA was detected in the feces of 22 pigs (7.4%, 95% CI 4.7–10.9%). A total of 103 households (66.5%, 95% CI 58.4–73.8%) had at least one pig that tested positive for anti-HEV IgG or IgM or HEV RNA. The prevalence of anti-HEV IgG and IgM in breeding pig (8–24 months) were higher than that in growing pigs (2–4 months) (p < 0.0001 and p = 0.008, respectively). HEV RNA was more frequently detected in 2–4-month-old pigs (9.2%, 95% CI 5.4–14.6%) than in ≥5-month-old pigs (4.8%, 95% CI 1.1–8.5%) without statistical significance (p = 0.142). HEV RNA showed 0–27.6% nucleotide difference at the partial ORF2 gene among the detected viruses, and a majority of them belonged to subtype 3a (20/22, 90.9%).

Conclusion

We found a high prevalence of HEV antibodies in the household-raised pig population in rural areas of the Philippines, which indicates the potential risk of HEV infection among local residents. Only genotype 3 of HEV was observed, and genetically diverse strains of HEV were found to be circulating in pigs in this study.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0322-z) contains supplementary material, which is available to authorized users.

Phylogenetic analysis of hepatitis E virus in domestic swine and wild boar in Germany

Hepatitis E virus (HEV) is an emerging non-enveloped positive strand RNA virus with worldwide distribution that can cause acute liver disease in humans. The virus has also been detected in both domestic and wild animals. In this study we investigated the presence of HEV in free-living wild boar as well as in domestic swine. A total of 105 domestic swine fecal samples and 124 wild boar sera were tested for the presence of HEV RNA by RT-PCR. A 241 nucleotide (nt) fragment from the capsid gene of HEV from one domestic swine and from 18 wild boars were amplified and sequenced. In addition, the complete capsid of three HEV sequences found in wild boar and the complete genomic sequence of the domestic swine HEV were obtained. Phylogenetic analyses based on both the 241 nt fragments as well as four complete capsid gene sequences demonstrated that all sequences belong to genotype HEV-3.

Hepatitis E virus of subtype 3i in chronically infected kidney transplant recipients in southeastern France

Hepatitis E virus (HEV) is a leading cause of waterborne acute hepatitis in developing countries. In Europe, HEV causes a zoonotic disease and is hyperendemic in southern France. Four HEV genotypes (1 to 4) have been defined, and the most used classification divides them into 24 subtypes. Autochthonous European HEV strains belong in majority to genotype 3. Subtypes 3c, 3f, and 3e are representative of the HEV diversity in France. HEV causes chronic hepatitis in solid-organ transplant recipients in Europe, and viral characteristics associated with chronicity are poorly documented. We sequenced 343-nucleotide-long HEV genomic fragments from the serum of eight chronically infected kidney transplant recipients and a near-full-length genome in one case. We identified in four patients (50%) HEV of subtype 3i, not described previously in France. If shorter genomic fragments were used in phylogenetic analyses, these HEV sequences were clustered with open reading frame 2 (ORF2) fragments labeled as subtype 3c. At least five of the eight HEV 3i sequences recovered from humans in our phylogenetic analyses were from chronically infected kidney transplant recipients. These data show that the description of the prevalence and geographical distribution of HEV subtypes may be partially inaccurate and that criteria for classification as 3i and 3c should be clarified. Extended molecular virology analyses are required to improve knowledge of HEV epidemiology and determinants of chronic HEV infection.

Estimation of hepatitis E virus (HEV) pig seroprevalence using ELISA and Western blot and comparison between human and pig HEV sequences in Belgium

Zoonotic transmission of hepatitis E virus (HEV) is of special concern, particularly in high income countries were waterborne infections are less frequent than in developing countries. High HEV seroprevalences can be found in European pig populations. The aims of this study were to obtain prevalence data on HEV infection in swine in Belgium and to phylogenetically compare Belgian human HEV sequences with those obtained from swine. An ELISA screening prevalence of 73% (95% CI 68.8-77.5) was determined in Belgian pigs and a part of the results were re-evaluated by Western blot (WB). A receiver operating characteristic curve analysis was performed and scenarios varying the ELISA specificity relative to WB were analysed. The seroprevalences estimated by the different scenarios ranged between 69 and 81% and are in agreement with the high exposure of the European pig population to HEV. Pig HEV sequences were genetically compared to those detected in humans in Belgium and a predominance of genotype 3 subtype f was shown in both swine and humans. The high HEV seroprevalence in swine and the close phylogenetic relationships between pig and human HEV sequences further support the risk for zoonotic transmission of HEV between humans and pigs.

Seroprevalence of hepatitis E virus in domestic pigs and wild boars in Switzerland

Hepatitis E is considered an emerging human viral disease in industrialized countries. Studies from Switzerland report a human seroprevalence of hepatitis E virus (HEV) of 2.6-21%, a range lower than in adjacent European countries. The aim of this study was to determine whether HEV seroprevalence in domestic pigs and wild boars is also lower in Switzerland and whether it is increasing and thus indicating that this zoonotic viral infection is emerging. Serum samples collected from 2,001 pigs in 2006 and 2011 and from 303 wild boars from 2008 to 2012 were analysed by ELISA for the presence of HEV-specific antibodies. Overall HEV seroprevalence was 58.1% in domestic pigs and 12.5% in wild boars. Prevalence in domestic pigs was significantly higher in 2006 than in 2011. In conclusion, HEV seroprevalence in domestic pigs and wild boars in Switzerland is comparable with the seroprevalence in other countries and not increasing. Therefore, prevalence of HEV in humans must be related to other factors than prevalence in pigs or wild boars.

Hepatitis E virus serological testing in kidney transplant recipients with elevated liver enzymes in 2007-2011 in southeastern France

Hepatitis E virus (HEV) is an emerging cause of acute and chronic hepatitis in Europe, particularly in solid organ transplant recipients. Anti-HEV IgG/IgM testing in kidney transplant recipients with liver biological disturbances indicated high HEV exposure in our geographical area and led to diagnose HEV infection in 6% of cases.

Age-related and regional differences in the prevalence of hepatitis E virus-specific antibodies in pigs in Germany

An increasing number of acute autochthonous human hepatitis E virus (HEV)-infections was noticed in Germany and other developed countries, most likely the result of a zoonotic virus transmission from pig, wild boar and deer. Currently there is still a lack of profound data concerning the actual prevalence of HEV-specific antibodies in domestic pig herds in Germany, in particular for regions with high pig density, and its age-dependency. 2273 domestic pig sera were collected in 2011 mainly from Bavaria, North Rhine-Westphalia and Lower Saxony from areas having a high pig density. Initially, 420 randomly selected pig sera were tested in three commercially available and in two in-house HEV-antibody ELISAs. 43.6% (183/420) to 65.5% (275/420) of the sera were demonstrated to be reactive against human pathogenic HEV genotypes 1 and/or 3. The majority of sera reacted only weakly or not at all with the rat HEV antigen with very few sera showing a stronger reactivity to this antigen compared to the genotype 3 antigen. The results of all three HEV-IgG tests, i.e. the PrioCHECK(®) HEV Ab porcine ELISA kit, the ID Screen(®) Hepatitis E Indirect Multi-species ELISA kit and the genotype 3 in-house ELISA were in good accordance. Therefore, the remaining sera were tested using the PrioCHECK(®) HEV Ab porcine ELISA kit. Samples with a borderline result were finally determined by application of the conjugate-modified recomLine HEV IgG assay. A total of 1065 of the 2273 sera (46.9%) were found to be anti-HEV IgG-positive. While 38.4% (306/796) of fatteners (age between 3 and 9 months) exhibited HEV-specific antibodies, 51.4% (759/1477) of sows (age older than 9 months) exhibited anti-HEV antibodies (P<0.001). Fatteners kept in Southern Germany had a significantly higher HEV IgG prevalence compared to fatteners kept in the high pig density federal states North Rhine-Westphalia and Lower Saxony but also in German federal states with a low pig density. In conclusion, the present study clearly demonstrates that a high percentage of domestic pigs in Germany have had contact with HEV. Seroprevalence depends on the pig's age and herd origin with the most significant regional variations for fatteners. The presence of anti-HEV-free herds may indicate that it is feasible to establish and sustain HEV-free pig herds. HEV seroprevalence still depends on the assay used for testing. This demonstrates an urgent need for test validation.

A longitudinal study revealing hepatitis E virus infection and transmission at a swine test station

Hepatitis E virus (HEV) is a zoonotic agent that causes acute hepatitis in humans, and infects several animal species, most importantly swine. In the current study, that presents the first evidence of HEV infections in pigs in Finland, genetic divergence and transmission of HEV was investigated among pigs at a swine test station at two occasions. In 2007, HEV RNA was found in 25% of pens, and 35% of 2-3 month-old pigs at the station. Three different isolates, comprising 13 sequences of HEV genotype 3 e that were imported from different farms were detected. In 2010, 39% of pigs were HEV RNA positive on weeks 1, 3, or 5 of a 3-month follow-up, and 11 sequences, all representing one of the isolates that was also present in 2007, were detected. The isolate was considered to be either re-introduced to, or to persist at the station, and it was transmitted between the pigs. The study sheds light on the rate and time of HEV transmission in swine, and describes the epidemiologic variability of HEV isolates over time.

Identification of European-type hepatitis E virus subtype 3e isolates in Japanese wild boars: molecular tracing of HEV from swine to wild boars

Nucleotide sequences of hepatitis E virus (HEV) isolates infecting wild boars in Mie prefecture, which is located in the central region of Japan and is far from the most prevalent regions of HEV infection in Japan, were determined and characterised. Among 144 serum samples of wild boars captured in Mie prefecture, 7 were positive for HEV-RNA. The nucleotide sequence of nearly the entire genome was determined for 4 of the 7 positive samples. Phylogenetic tree analyses indicated that 6 samples were subtype 3e and 1 was subtype 3a among the 7 isolates. We identified the indigenization of subtype 3e isolates in Japanese wild boars. Furthermore, 5 subtype 3e isolates were closely related and were located in the peripheral branch of subtype 3e isolates from European countries in the phylogenetic tree. The structure indicated that the ancestor of the 5 subtype 3e isolates originated in Europe. The phylogenetic structure and coalescent analyses suggested that the subtype 3e isolates entered Japan from Europe by importation of large-race pigs around 1966. The results also indicated that several lineages of subtype 3e expanded to a wide area of Japan around 1992 and 1 of the lineages was indigenized in wild boars in Mie prefecture between 1992 and 2009. The appearance of a wild boar cluster in the peripheral branch in the phylogenetic lineage may indicate the direction of gene flow of HEV subtype 3e from swine to wild boars. Clarification of the transmission direction or route should be helpful to prevent a future endemic or epidemic of HEV infection.

Epidemiology of mammalian hepatitis E virus infection

Mammalian hepatitis E virus (HEV), the etiological agent of hepatitis E in humans, is a recently discovered infectious agent. It was identified for the first time in 1983 using electron microscopy on a faecal specimen of a person infected with non-A, non-B enterically-transmitted hepatitis. Based on retrospective and prospective studies, HEV was long described as one of the leading causes of acute viral hepatitis in tropical and subtropical countries, whereas in developed countries hepatitis E was considered an imported disease from HEV hyperendemic countries. Data from studies conducted during the past decade have greatly shifted our knowledge on the epidemiology and clinical spectrum of HEV. Recently, it has been shown that contrary to previous beliefs, hepatitis E is also an endemic disease in several developed countries, particularly in Japan and in Europe, as evidenced by reports of high anti-HEV immunoglobulin G prevalence in healthy individuals and an increasing number of non-travel-related acute hepatitis E cases. Moreover, a porcine reservoir and growing evidence of zoonotic transmission have been reported in these countries. This review summarizes the current knowledge on the epidemiology and prevention of transmission of mammalian HEV.

Infection with hepatitis E virus in kidney transplant recipients in southeastern France

Hepatitis E virus (HEV) is an emerging cause of acute hepatitis in Europe, particularly in southern France, and HEV is a new causative agent of chronic hepatitis and cirrhosis in immunocompromised patients. However, the data regarding HEV infection after kidney transplantation are still scarce with respect to the clinical issues that have been raised, and no study has specifically focused on kidney transplant recipients. This study described the clinical features and outcomes of HEV infections in a cohort of kidney transplant recipients living in southeastern France. The epidemiological, clinical, and virological characteristics of HEV infections diagnosed by PCR over a 53-month period were retrospectively analyzed in a cohort of 1,350 kidney transplant recipients monitored at the Marseille University Hospital. Sixteen HEV infections were diagnosed, all of which were autochthonous and involved genotype 3 viruses (HEV-3). Chronic infections occurred in 80% of these patients and resolved in half of the cases after a median time of 39 months. The rate of HEV clearance was 54% after a decrease in the dose of immunosuppressants. One patient developed liver cirrhosis 14 months after infection and experienced acute rejection after a decrease in the dose of immunosuppressants. Autochthonous HEV-3 infections in kidney transplant recipients progress to chronicity in most cases and might be complicated by early liver cirrhosis. Chronic HEV infection can resolve following the reduction of immunosuppressive therapy, but ribavirin may be required if reduction of the immunosuppressant dose is not associated with HEV clearance or is inappropriate for the patient management.

Discrepancy between anti-hepatitis E virus immunoglobulin G prevalence assessed by two assays in kidney and liver transplant recipients

BACKGROUND

Hepatitis E virus (HEV) is an emerging clinical threat in Europe among kidney and liver-transplant recipients. The incidence and prevalence of HEV infection in this special population are poorly known. False-negative results have been observed for anti-HEV IgG detection in severely immunocompromized persons. Moreover, large discrepancies have been reported between rates of anti-HEV IgG detection in blood donors and hepatitis E cases.

OBJECTIVES

To compare anti-HEV IgG and IgM prevalence using two different commercial microplate enzyme-immuno assays (MEIAs) (Adaltis and Wantai) in 64 kidney-/liver-transplant recipients.

STUDY DESIGN

Serum samples tested in our routine clinical practice over the 12/2009-12/2011 period with Adaltis MEIAs were retrospectively tested using Wantai MEIAs. IgG-positive sera were further tested by an immunoblot while those found IgM-positive were further tested with an immunochromatography rapid test and for the presence of HEV RNA.

RESULTS

Positive results on anti-HEV IgG testing were obtained for seven (10.9%) compared to 20 (31.3%) serum samples with Adaltis and Wantai assays, respectively (p=0.005). Then, 6/7 (86%) of the serum samples positive with Adaltis and 16/20 (80%) of those positive with Wantai were positive with the immunoblot. One patient with chronic HEV infection was IgG-negative with both MEIAs. Regarding anti-HEV IgM, Adaltis and Wantai assays were concordant for 97% of the serum samples, prevalence being 8% with both MEIAs.

CONCLUSIONS

The accuracy of currently available commercial or in-house anti-HEV IgG MEIAs should be tested comparatively on a panel of serum samples collected from solid organ-transplant recipients, including some who experienced PCR-documented HEV infection.

Bats worldwide carry hepatitis E virus-related viruses that form a putative novel genus within the family Hepeviridae

Hepatitis E virus (HEV) is one of the most common causes of acute hepatitis in tropical and temperate climates. Tropical genotypes 1 and 2 are associated with food-borne and waterborne transmission. Zoonotic reservoirs (mainly pigs, wild boar, and deer) are considered for genotypes 3 and 4, which exist in temperate climates. In view of the association of several zoonotic viruses with bats, we analyzed 3,869 bat specimens from 85 different species and from five continents for hepevirus RNA. HEVs were detected in African, Central American, and European bats, forming a novel phylogenetic clade in the family Hepeviridae. Bat hepeviruses were highly diversified and comparable to human HEV in sequence variation. No evidence for the transmission of bat hepeviruses to humans was found in over 90,000 human blood donations and individual patient sera. Full-genome analysis of one representative virus confirmed formal classification within the family Hepeviridae. Sequence- and distance-based taxonomic evaluations suggested that bat hepeviruses constitute a distinct genus within the family Hepeviridae and that at least three other genera comprising human, rodent, and avian hepeviruses can be designated. This may imply that hepeviruses invaded mammalian hosts nonrecently and underwent speciation according to their host restrictions. Human HEV-related viruses in farmed and peridomestic animals might represent secondary acquisitions of human viruses, rather than animal precursors causally involved in the evolution of human HEV.

Detection of IgM and IgG against hepatitis E virus in serum and meat juice samples from pigs at slaughter in Bavaria, Germany

Hepatitis E virus (HEV) is an emerging foodborne pathogen with domestic and wild pigs (and likely other species such as deer or rabbits) recognized as reservoir. Pathogenesis in pigs usually leads to an asymptomatic course of disease. Since there is no enzyme-linked immunosorbent assay (ELISA) kit for the detection of anti-HEV antibodies in pigs commercially available, the objective of this study was to assess the seroprevalence in fattening pigs at slaughter and at herd level using a newly developed ELISA based on genotype (GT) 1 and GT 3 in Bavaria, Germany. Based on 516 serum and 198 meat juice samples collected from different herds at four different Bavarian slaughterhouses, the overall seroprevalence of anti-HEV IgG in serum and meat juice samples was 68.6% and 67.6%, respectively. Analyzing the serum for the presence of anti-HEV IgM, 36/516 (7%) were positive for anti-HEV IgM. At herd level, most of the herds were seropositive for anti-HEV antibodies. The present study shows that HEV is widespread among the Bavarian pig population and that some pigs might test positive for anti-HEV IgM even at the age of slaughter. Also, meat juice serves as an equivalent matrix to serum to test for anti-HEV antibodies in pigs.

Hepatitis E virus infection in patients infected with the human immunodeficiency virus

Hepatitis E virus (HEV) is a newly-identified causative agent of acute and chronic hepatitis in severely immunocompromized patients. The present study sought to assess the prevalences of past, recent, on-going, and chronic HEV infections in patients infected with human immunodeficiency virus (HIV) in Marseille, South-eastern France, and to determine if they were correlated with the patients' immunological status or with cirrhosis. Anti-HEV IgG and IgM and HEV RNA testing were concurrently performed on the plasma from 184 patients infected with HIV, including 81 with a CD4+ T-lymphocyte count (CD4 count) <50 cells/mm(3) and 32 with a cirrhosis. Prevalence of anti-HEV IgG and IgM was 4.4% (8/184) and 1.6% (3/184), respectively. Past, recent, and on-going infections were observed in 3.3% (6/184), 1.6% (3/184), and 0.5% (1/184) of the patients, respectively. Anti-HEV antibodies prevalence did not differ significantly according to CD4 count, cirrhosis, sex, age, mode of HIV transmission, and infection with hepatitis B or C virus. Anti-HEV IgG seroreversion was observed in two patients. The patient whose plasma tested positive for HEV RNA had a CD4 count <50 cells/mm(3) ; HEV genotype was 3f. In this patient, longitudinal testing showed HEV RNA positivity during a 10-month period, indicating chronic HEV infection; in contrast, anti-HEV IgG never tested positive. Further studies are needed to evaluate the performance of commercial HEV serological assays in patients infected with HIV and to assess the actual incidence, prevalence, and outcome of HEV infection in this special group of patients. HEV RNA testing is necessary for such purposes.

Hepatitis E virus genotype 3f in pigs in New Caledonia

BACKGROUND

Hepatitis E virus (HEV) is highly prevalent in farm pigs worldwide and an increasing body of data from industrialised countries suggests that it is an agent of a porcine zoonosis.

METHODS

We used in-house real-time reverse transcription polymerase chain reaction to study HEV infection in 4-26-week-old pigs on a pig farm in New Caledonia, Oceania, for which no data are available.

RESULTS

HEV RNA was detected in faeces from 6 of 92 (6.5%) pigs tested and all were 9-16 weeks old. Phylogenetic analysis showed that the HEV open reading frame 1 and 2 sequences recovered in this study formed a single cluster among HEV genotype 3 subtype f.

CONCLUSIONS

Our work shows for the first time that pigs are a reservoir for HEV in New Caledonia. Further studies are needed to assess the prevalence and phylogenetic relationships of HEV in pigs and humans in this French overseas collectivity.

Widespread distribution of hepatitis E virus in Spanish pig herds

Background

Hepatitis E virus (HEV) infection is a serious health problem in developing countries and is also increasingly reported in industrialized regions. HEV is considered a zoonotic agent and strains isolated from swine and human sources are genetically similar. Thus, HEV is of increasing importance to both public and animal health. The aim of the present study was to evaluate the distribution of HEV in a large population of pigs from herds located in different autonomous regions throughout Spain.

Results

The presence of anti-HEV IgG antibodies was analyzed in 1141 swine serum samples (corresponding to 381 pigs younger than 6 months and 760 pigs older than 6 months) collected from 85 herds. Herds were located in 6 provinces in 4 autonomous regions throughout Spain. At least one pig tested positive for anti-HEV IgG in over 80% of herds. Of individual pigs, 20.4% (233/1141) were positive for anti-HEV IgG, with the prevalence being higher in adult pigs than in those under 6 months (30.2% vs. 15.5%). A subset of serum samples taken at 2- to 5-week intervals showed that seroprevalence dropped between 3 and 11 weeks of age, and then rose significantly by the 15th week. Pigs were also examined for the presence of HEV-RNA by RT-PCR. Of pigs tested for the presence of HEV-RNA 18.8% (64/341) were positive, with at least one pig in almost half of the herds testing positive. HEV-RNA amplicons from several positive pigs were sequenced and all were of genotype 3.

Conclusions

HEV was found to be widely distributed among swine farms across Spain, with the prevalence being highest among animals older than 6 months. These results indicate that HEV infection either is or is likely to become endemic in the Spanish swine population.

The molecular epidemiology of hepatitis E virus infection

Molecular characterization of various hepatitis E virus (HEV) strains circulating among humans and animals (particularly swine, deer and boars) in different countries has revealed substantial genetic heterogeneity. The distinctive four-genotype distribution worldwide of mammalian HEV and varying degrees of genetic relatedness among local strains suggest a long and complex evolution of HEV in different geographic regions. The population expansion likely experienced by mammalian HEV in the second half of the 20th century is consistent with an extensive genetic divergence of HEV strains and high prevalence of HEV infections in many parts of the world, including developed countries. The rate and mechanisms of human-to-human transmission and zoonotic transmission to humans vary geographically, thus contributing to the complexity of HEV molecular evolution.

Hepatitis E virus infection in sheltered homeless persons, France

To determine the prevalence of hepatitis E virus (HEV) infection among sheltered homeless persons in Marseille, France, we retrospectively tested 490 such persons. A total of 11.6% had immunoglobulin (Ig) G and 2.5% had IgM against HEV; 1 person had HEV genotype 3f. Injection drug use was associated with IgG against HEV.

Viral and antibody HEV prevalence in swine at slaughterhouse in Italy

Hepatitis E is an acute disease of humans caused by a small RNA virus, Hepatitis E virus (HEV). In recent years, an increasing number of autochthonous human infections have been reported in industrialized countries. Genotype 3 is the main HEV type circulating in swine, and is also reported in sporadic cases of hepatitis E in humans worldwide. To date one serotype has been described. We have conducted a survey to detect antibodies against HEV in 48 swine at a slaughterhouse in Northern Italy, using ELISA test. Mean seroprevalence in the studied animal group was 87.0%. Bile, liver and feces from the 48 animals were also collected, and HEV RNA was detected by nested reverse transcription-polymerase chain reaction, amplifying a fragment of the ORF2. HEV genome was most frequently detected in bile samples (51.1%), followed by feces (33.3%) and liver (20.8%). Thirty-one out of 48 studied pigs (64.6%) were positive for HEV RNA in at least one sample. Overall, HEV RNA was found at a statistically higher rate in the 3-4-month-old than in 9-10-month-old animals (95.0% vs. 42.9%). Genetic characterization of swine strains identified was performed by sequencing and database alignment. Phylogenetic analysis on the nucleotide sequences from 14 positive PCR products indicated that all strains belonged to genotype 3, clustering in two branches subtypes g3c and g3f.

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

Hepatitis 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.

Much meat, much malady: changing perceptions of the epidemiology of hepatitis E

Hepatitis E, which is caused by hepatitis E virus (HEV), may now be considered a zoonosis as well as an anthroponosis. Pigs, boars and deer have been identified as reservoirs, and their flesh and entrails--as meat and offal--as vehicles of HEV transmission. Shellfish also act as vehicles. Dietary, gastronomic and culinary preferences influence how extensively HEV conveyed by these vehicles can be inactivated before their ingestion by the host. Another route of infection is paved by HEV that is enterically shed by humans and by live animals into the environment. Although anthroponotic transmission of HEV is primarily environmental, zoonotic transmission may proceed along both foodborne and environmental routes.

Prevalence of Hepatitis E virus-specific antibodies in sera of German domestic pigs estimated by using different assays

Hepatitis E virus is the causative agent of an acute hepatitis in humans. In industrialized countries, autochthonous hepatitis E cases in the past were mainly of undetermined origin, whereupon nowadays some cases may be linked to zoonotic transmission of HEV from pigs and wild boars. In contrast to several European countries the HEV status of German domestic pigs and a possible risk of transmission are unknown so far. Here, a novel peptide-based ELISA was used to detect HEV-specific antibodies in 1072 sera from German domestic pigs resulting in an average seroprevalence of 49.8% indicating widespread HEV infections in these animals. A comparative testing of 321 randomly selected sera revealed a seroprevalence of 64.8% when using a commercially available ELISA and 43.9% for the novel peptide-based ELISA but concordant results were obtained in both tests only for 56.1% of the sera. Additional re-testing of 23 randomly selected sera with a modified commercially available immunoblot revealed discordant results also. The use of different antigens and the measurement of different immunoglobulin classes are considered to be responsible for the observed variations of the results. Though the present study revealed a high seroprevalence of HEV in the German domestic pig population and a potential risk of transmission to humans, the differing results of the tests highlight the necessity of a standardization of serological assays for comparative seroprevalence and longitudinal studies.

Detection of hepatitis E virus of genotype 3 in a farm pig in Kinshasa (Democratic Republic of the Congo)

Autochthonous hepatitis E is an emerging disease in industrialized countries where a growing body of data indicates that pigs represent a reservoir for hepatitis E virus (HEV) of genotype 3 or 4. In Africa, only HEV genotypes 1 and 2 have been identified in hepatitis E outbreaks as well as in sporadic cases. We aimed to investigate whether commercial pigs in sub-Saharan Africa might represent an HEV reservoir using molecular assays. Faecal samples from 40 pigs of the Pietrain race housed in a farm in Kinshasa (Democratic Republic of the Congo) were tested using in-house real-time reverse transcription (RT)-PCR and sequencing assays. HEV RNA was detected in faeces of one (2.5%) pig, and the HEV sequence obtained from this pig was classified genotype 3c, and was genetically related to human HEV sequences from France (89-92% nucleotide similarity) and pig HEV sequences from The Netherlands (88-91% nucleotide similarity). Epidemiological investigations revealed that Kinshasa farm pigs tested in the present study are descendants of pigs imported from Belgium in 2002, suggesting that pig HEV genotype 3c recovered in our study may have been imported from Belgium to Democratic Republic of the Congo. Our findings, although needing to be confirmed in further studies, also suggest that pigs in sub-Saharan Africa may be an HEV reservoir.