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 in domestic pigs and surface waters in Slovenia: Prevalence and molecular characterization of a novel genotype 3 lineage

A novel hepatitis E virus (HEV) genotype 3 lineage was identified in Slovenian pig herds. Stool samples from six Slovenian pig farms were collected and tested for the presence of HEV RNA. Of 85 individual samples 15 (20.3%) were positive for HEV RNA of which 2/38 (5.3%), 6/21 (28.6%) and 7/26 (26.9%) were from suckling, weanling and fattening pigs, respectively. Additionally, 51 pooled porcine stool samples were tested in one of the biggest pig farm and the estimated infection rate of individual pig was calculated, resulting in 7.8%, 10.6% and 24.2% for suckling, weanling and fattening pigs, respectively. The majority of HEV positive porcine samples were from the same pig farm. Out of 17 Slovenian patients with confirmed recent hepatitis E in the period 1999–2011, the serum samples of 10 patients were tested and 3 samples turned out to be HEV RNA positive. Furthermore, 60 surface water samples were tested throughout the country, of which 2 (3.3%) were positive for HEV RNA, one of them in the near vicinity of a pig farm. All HEV strains were analysed at 5’ ORF1 and 5’ ORF2 regions and both genome regions confirmed that Slovenian HEV strains represent a distinct genotype 3 lineage, diverse from all other genotype 3 lineages available in GenBank and described in the literature to date. All but one HEV strains detected in pigs in Slovenia represent a monophyletic branch in phylogenetic trees, with a high degree of sequence identity. One human HEV strain belonged to genotype 1 and two to genotype 3 but did not match the new genotype 3 lineage detected in Slovenian pig herds.     

Bayesian estimation of hepatitis E virus seroprevalence for populations with different exposure levels to swine in The Netherlands

Hepatitis E virus (HEV) is ubiquitous in pigs worldwide and may be zoonotic. Previous HEV seroprevalence estimates for groups of people working with swine were higher than for control groups. However, discordance among results of anti-HEV assays means that true seroprevalence estimates, i.e. seroprevalence due to previous exposure to HEV, depends on choice of seroassay. We tested blood samples from three subpopulations (49 swine veterinarians, 153 non-swine veterinarians and 644 randomly selected individuals from the general population) with one IgM and two IgG ELISAs, and subsets with IgG and/or IgM Western blots. A Bayesian stochastical model was used to combine results of all assays. The model accounted for imperfection of each assay by estimating sensitivity and specificity, and accounted for dependence between serological assays. As expected, discordance among assay results occurred. Applying the model yielded seroprevalence estimates of approximately 11% for swine veterinarians,approximately 6% for non-swine veterinarians and approximately 2% for the general population. By combining the results of five serological assays in a Bayesian stochastical model we confirmed that exposure to swine or their environment was associated with elevated HEV seroprevalence.     

Hepatitis E virus is prevalent in the pig population of Lao People's Democratic Republic and evidence exists for homogeneity with Chinese Genotype 4 human isolates

The objective of this study was to determine the prevalence and genotypic range of Hepatitis E virus (HEV) in the pig population of northern Lao People's Democratic Republic (PDR). We collected 181 faecal samples from indigenous-breed pigs ≤6 months of age and the faeces was stored in RNA stabilisation buffer due to cold-chain and transport limitations. Twenty-one (11.6%) pigs had detectable HEV RNA and 43.5% of village pig herds were infected. Based on a 240 base pair-nucleotide sequence flanking the junction of open reading frames 1, 2 and 3 (ORF1, ORF2 and ORF3) the isolates were phylogenetically classified within genotype 4. Phylogenetic analyses revealed distinct genetic groupings of the Lao HEV isolates and two groups clustered with human and pig HEV isolates from China. This was the first study to demonstrate genotype 4 HEV in Lao PDR and indicates pigs are a potential reservoir for human HEV infection.     

湖北地区出口猪及不同人群中戊型肝炎病毒感染调查研究

〔目的〕调查湖北地区出口猪以及不同人群中戊型肝炎病毒的流行情况,为制定预防措施提供依据。〔方法〕从湖北地区8个出口猪场中共采集3个月龄以下猪的血清203份,3个月以上猪的血清637份。从不同人群(包括猪场和屠宰厂从业人员、农村居民以及献血员中共采集1585份血清样品。用酶联免疫方法分别检测戊型肝炎病毒抗体以及抗原,对部分样品采用实时荧光聚合酶链反应检测戊型肝炎病毒核酸。〔结果〕3个月龄以下和3个月龄以上猪血清中戊型肝炎病毒抗体的阳性率分别为56.65%和87.13%,2者间差异具有显著性(t=7.79,p<0.01);戊型肝炎病毒抗原的阳性率分别为9.35%和10.36%,2者间差异无显著性。在328份猪血清中,抗原和核酸的符合率为78.80%。猪场和屠宰厂从业人员、农村居民以及献血员中戊型肝炎病毒IgG抗体的阳性率分别为55.72%(263/472)、31.63%(99/313)、27.00%(81/300)和33.40%(167/500)。猪场从业人员戊型肝炎病毒IgG抗体阳性率与其他3类人群的相比,具有非常显著性差异(t=8.88,p<0.01)。〔结论〕猪群中戊型肝炎感染率较高,与猪密切接触人群的感染率高于其他人群。因此,应加强出口猪场的管理,减少戊型肝炎病毒在人畜之间的传播。     

Seroprevalence and distribution of hepatitis E virus in various ethnic groups in Gansu province,China

Gansu province is located in northwestern China and is home to 45 ethnic groups including Han, Hui, Zang and others. Different ethnic groups have varying involvement with livestock and meat consumption, especially pork. To investigate the prevalence of hepatitis E virus (HEV) infection and the distribution of HEV genotypes among the major ethnic groups in Gansu province, 2090 serum samples were collected from individuals from four regions and three ethnic groups, the Han, Hui and Zang. All serum samples were tested for anti-HEV IgG and IgM antibodies, as well as HEV antigen, and selected samples were then tested for HEV RNA. The data showed that the seroprevalence of anti-HEV IgG in the Hui, Han and Zang ethnic groups from the four regions was 8.9%, 18.7% and 32.9%, respectively, and these differed significantly (P < 0.05). The seroprevalence of anti-HEV antibody for each ethnic group varied among the different regions. In general, within the same region, the three ethnic groups also show differences. Genomic analysis indicated that HEV isolated from humans belonged to genotype 4, and resembled closely swine HEV isolates from Gansu province. The seroprevalence of anti-HEV antibodies was in accordance with the amount of contact with pigs in the different regions. Pigs are the primary host for HEV, so people in frequent contact with pigs may be at risk of zoonotic infection. However, populations that have rare contact with pigs are more likely to be susceptible to HEV when exposed, suggesting that should be the target of vaccination.     

Comparison of hepatitis E virus genotypes from rabbits and pigs in the same geographic area: No evidence of natural cross-species transmission between the two animals

Domesticated pigs have been shown to be a reservoir of genotypes 3 and 4 hepatitis E virus (HEV). Farmed rabbits were recently recognized as the host of a novel virus, rabbit HEV. In order to determine whether HEV is transmitted naturally between rabbits and pigs, a survey on HEV infections was conducted in rabbits and pigs aged 2–4 months from rabbit and pig farms located near to each other in nine villages in three counties of Hebei Province, China. The overall anti-HEV antibody positivity rates in serum samples of swine and rabbits were 61.7% (58/94) and 23.2% (67/289), and the positive rates for HEV RNA were 23.4% (22/94) and 10% (29/289), respectively. In addition, 37 of 125 swine fecal samples (29.6%) were HEV RNA positive. The nucleotide sequences of a 304 bp region within HEV ORF2 have identity ranging from 84.5% to 100% among the rabbit isolates and from 82.3% to 100% among the swine isolates. In contrast, the nucleotide identity between the two species groups was only 72–76.6%. Consequently, the two groups were clearly separated in the phylogenetic tree that showed all of the rabbit isolates are closely related to the rabbit HEV reported recently and the swine isolates belong to genotype 4, including subgenotypes 4a, 4c and 4d. The results showed that HEV is highly prevalent in farmed rabbits and pigs in these areas. However, genotype 4 HEV and rabbit HEV are circulating separately in pigs and rabbits in the same area. In conclusion, there was no evidence of cross-species transmission of HEV between pigs and rabbits. The frequency of HEV transmission events between these two animal species is likely low in commercial farms.     

Seroprevalence of hepatitis E virus infection, rural southern People's Republic of China

Genotype 4 hepatitis E virus (HEV) is the dominant cause of hepatitis E in the People's Republic of China; swine are the principal reservoir. Our study was conducted in 8 rural communities of southern China, where families keep pigs near their homes. Phylogenetic analysis showed that 23 of 24 concurrent virus isolates from this region are genotype 4 strains. Among the study populations, immunoglobulin G anti-HEV seroprevalence accumulated with age at approximately equal to 1% per year for persons < or =60 years of age. After age 30 years, seroprevalence increased at higher rates for male than for female study participants. The overall seroprevalence was 43% (range 25%-66%) among the communities. Infection rates were higher for participants between 25 and 29 years of age. The results suggest that HEV infection probably has been endemic in southern China for at least 60 years, with swine being the principal reservoir of human HEV infection in recent years.     

Hepatitis E Virus Antibodies in Patients with Chronic Liver Disease

In the United States, the seroprevalence rate for hepatitis E virus (HEV) is ≈20%. This study examined HEV seroprevalence in persons with and without chronic liver disease. Our data indicate that HEV seropositivity is high in patients with chronic liver disease and that HEV seroprevalence increases significantly with age.     

Anti-HEV seroprevalence in the area of Lecce

Hepatitis E virus (HEV) is the causative agent of an enterically transmitted viral hepatitis associated with inadequate hygienic conditions. Hepatitis E is endemic in developing countries where it occurs both in sporadic and epidemic form. Outbreaks have been reported in different areas of the world. The aim of the present work was to assess the seroprevalence of HEV infection in the general population and in different risk groups in the area of Lecce. The presence of anti-HEV antibodies was ascertained by qualitative ELISA (Abbott HEV EIA) and Western Blot (Recomblot HEV IgG/IgM, Mikrogen). The prevalence of anti-HEV in the general population was 2.9% while in intravenous drug users, hemodialized patients and immigrants the seroprevalence rates were 0.7%, 4.3% and 15.3% respectively. Our data show a circulation of HEV at low level in the area of Lecce which is endemic for hepatitis A. Higher seroprevalence rates were found in hemodialized patients and remarkably in immigrants coming from endemic areas like Turkey.     

Serological studies of influenza viruses in pigs in Great Britain 1991-2.

Samples from a sow serum bank representative of the pig population of Great Britain collected during 1991-2, were examined for antibodies to influenza A, B and C viruses, using viruses which had been isolated from a variety of hosts. For influenza A viruses there was evidence of the continued circulation of classical swine H1N1 virus (26%) seroprevalence), and human H3N2 viruses (39%) which are antigenically most closely-related to A/Port Chalmers/1/73 virus. In addition antibodies were detected to A/swine/England/201635/92 (8%), a strain of H3N2 virus which appears to have arisen by antigenic drift from conventional H3N2 swine strains. Specific antibodies (2%) were detected to an H1N1 virus (A/swine/England/195852/92) related most closely to avian H1N1 strains. In tests with human H1N1 and H3N2 viruses, excluding isolates from pigs, the highest seroprevalence was detected to the prevailing strains from the human population. Serological tests with avian H4 and H10, human H2, equine 1 and 2 influenza A viruses were all negative. Seven pigs seropositive by haemagglutination-inhibition, virus neutralization and immunoblotting assays for antibody to influenza B virus, were randomly distributed geographically suggesting that influenza B viruses may be transmitted to pigs but fail to spread. The seroprevalence to influenza C viruses was 9.9% indicating that these viruses are widespread in pigs. These results provide further evidence that the pig can be infected by a number of influenza viruses, some of which may have significance in the epidemiology of human influenza.     

Hepatitis E virus genotype 3 in humans and Swine, Bolivia

We determined the seroprevalence of hepatitis E virus (HEV) in persons in 2 rural communities in southeastern Bolivia and the presence of HEV in human and swine fecal samples. HEV seroprevalence was 6.3%, and HEV genotype 3 strains with high sequence homology were detected.     

Hepatitis E as zoonosis

The hepatitis E virus (HEV) the causative agent of hepatitis E, is a non-enveloped RNA virus. HEV is transmitted through oral consumption of contaminated food and water According to the currently knowledge now be considered as zoonosis. The main reservoir of HEV are pigs, boars and deer. For the first time HEV was isolated from animals (pigs) in 1997 in the U.S. Genetic analysis of strains isolated from pigs showed high similarity to strains HEV isolated from humans. This was the first evidence showing that HEV is a zoonosis. Further studies have shown that occupational groups e.g. veterinarians, swine breeders with close contact to pigs have an increased risk for HEV infections. The additional evidence supported the zoonotic potential of HEV were reports of acute hepatitis E after the consumption of undercooked meat from deer and wild boar. Infection of HEV in the domestic pig and wild boar population in Europe is widespread.     

Prevalence of Hepatitis E Virus Infection in Pigs at the Time of Slaughter,United Kingdom, 2013

Since 2010, reports of infection with hepatitis E virus (HEV) have increased in England and Wales. Despite mounting evidence regarding the zoonotic potential of porcine HEV, there are limited data on its prevalence in pigs in the United Kingdom. We investigated antibody prevalence, active infection, and virus variation in serum and cecal content samples from 629 pigs at slaughter. Prevalence of antibodies to HEV was 92.8% (584/629), and HEV RNA was detected in 15% of cecal contents (93/629), 3% of plasma samples (22/629), and 2% of both (14/629). However, although HEV is prevalent in pigs in the United Kingdom and viremic pigs are entering the food chain, most (22/23) viral sequences clustered separately from the dominant type seen in humans. Thus, pigs raised in the United Kingdom are unlikely to be the main source of human HEV infections in the United Kingdom. Further research is needed to identify the source of these infections.     

Seroprevalence for Hepatitis E and Other Viral Hepatitides among Diverse Populations,Malawi

Data on prevalence of hepatitis E virus (HEV) in Malawi is limited. We tested blood samples from HIV-uninfected and -infected populations of women and men enrolled in research studies in Malawi during 1989–2008 to determine the seroprevalence of HEV, hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV). Samples were tested for IgG against HEV, total antibodies against HAV and HCV, and presence of HBV surface antigens. Of 800 samples tested, 16.5% were positive for HEV IgG, 99.6% were positive for HAV antibodies, 7.5% were positive for HBV surface antigen, and 7.1% were positive for HCV antibodies. No clear trends over time were observed in the seroprevalence of HEV, and HIV status was not associated with hepatitis seroprevalence. These preliminary data suggest that the seroprevalence of HEV is high in Malawi; the clinical effects may be unrecognized or routinely misclassified.     

福建省戊型肝炎病毒感染的血清流行病学调查

目的了解福建省动物种群及人群中戊型肝炎病毒(HEV)的感染情况。方法收集猪、犬、乳牛、山羊和啮齿动物(黄胸鼠及褐家鼠)等5种与人类关系密切的哺乳动物血清标本共1151份,收集普通人群血清标本2209份,暴露人群血清标本1722份,应用ELISA检测抗-HEV IgG抗体。结果不同动物HEV感染率有差异(x2=406.25,P<0.01),其中猪的感染率为71.31%,散养家猪(70.00%-94.12%)HEV感染率高于大型专业养猪场(39.77%),不同生长期(≥4月龄)的猪其HEV感染率未见不同。普通人群HEV的阳性率为23.3%,暴露人群HEV阳性率为33.3%;暴露人群阳性率显著高于普通人群。在暴露人群中与鸡密切接触者,HEV的阳性率显著高于与猪密切接触者。HEV阳性率有随年龄的增长而上升的趋势,在普通人群中,男、女性HEV阳性率差异无统计学意义(P>0.05);但在暴露人群中男性HEV阳性率显著高于女性。结论猪和暴露人群HEV的感染率较高;与猪、鸡密切接触者HEV阳性率高于普通人群,证明了HEV可能是一种人兽共患病。     

Seroprevalence of hepatitis E antibodies and risk profile of HEV seropositivity in The Netherlands, 2006-2007

SHepatitis E virus (HEV) is now considered an endemic pathogen in industrialized countries, leading to acute and sometimes chronic hepatitis, mostly in vulnerable people. The endemic sources are unclear. A survey in The Netherlands in 2006-2007 showed a 1·9% seroprevalence of HEV antibodies measured by ELISA and confirmed by immunoblot in a nationwide sample. Overall, in 134/7072 (1·9%) seropositive individuals, older age (P<0·01), being male (P<0·01), working with patients (P=0·03), working with animals (P=0·07), recent diarrhoeal complaints (P=0·07) and adhering to a religion that considers pigs unclean (P<0·01) were independently associated with seropositivity in multivariate analysis. Sub-analysis of 59/4022 (1·5%) anti-HEV antibody-positive subjects with probable endemic exposure showed independent association with youngest household member being aged <5 years or between 19 and <65 years (P=0·05) in multivariate analysis. These findings may contribute to a better understanding of the sources of endemic HEV exposure, and also highlight the need for systematic epidemiological and serological evaluation of new cases.