Detection and Characterization of Hepatitis E Virus in Domestic Pigs of Different Ages in Portugal

This study represents the primary hepatitis E virus (HEV) surveillance in domestic pigs in Portugal, five pig farms were investigated in 5 different Portuguese regions, ten faecal samples were collected at four different stages of the production. All faecal samples were tested for hepatitis E virus by real-time RT-PCR. At least one sample from each farms of all age groups tested positive for HEV. The prevalence in the pig herds varied from 10% to 30% and the mean prevalence was 32% in weaners, 20% in growers, 32% in fatteners and 4% in adult dry sows. Phylogenetic analysis of the detected HEV sequences indicated that the circulating virus strains belong under the genotype 3.     

Outbreaks of classical swine influenza in pigs in England in 1986

Serum samples from pig herds in Great Britain have been examined for antibodies to influenza virus since 1968. Antibodies to H3N2 virus strains have been found since 1968 and the serological data presented here suggests that H3N2 virus strains continue to persist in the pig population. An outbreak of acute respiratory disease occurred in a 400-sow unit. The outbreak was characterised by coughing, anorexia, fever, inappetence and loss of condition. The gilts and weaners were affected and the morbidity approached 100 per cent. An influenza A virus designated A/Swine/Weybridge/117316/86 (H1N1) was isolated from the herd and 28 paired serum samples from the affected animals showed increases in the haemagglutination inhibition titres to this isolate. Haemagglutinin and neuraminidase characterisation indicated that the virus is similar to H1N1 viruses isolated recently from pigs in Europe. A total of 91 herds experiencing respiratory disease were investigated, of which 42 gave positive reactions in the haemagglutination inhibition test. Antibodies to A/Port Chalmers/1/73 (H3N2) were also detected in some of the herds but it is not known whether this strain plays any role in the current respiratory disease problems in pigs.     

河南省猪场戊型肝炎病毒流行病学调查

为了解河南地区猪戊型肝炎感染情况,同时掌握该地区猪感染戊型肝炎病毒的基因型,对来自河南新乡、平顶山、南阳等地区不同商品猪场血清、肝脏、粪样品,采用ELISA技术检测猪血清中抗HEV特异性抗体水平,并使用套式RT-PCR检测肝脏和粪便中猪戊型肝炎病毒核酸。结果显示530份样品中HEV抗体阳性率0.6%,HEV RNA均为阴性,推测目前河南省猪戊型肝炎病毒感染率较低。     

Postweaning multisystemic wasting syndrome in Danish pig herds: productivity, clinical signs and pathology

A case-control study of 74 herds with postweaning multisystemic wasting syndrome (pmws) and 74 matched control herds was carried out. In the case herds the mortality rates of weaner and finisher pigs were 11.2 and 5.2 per cent respectively, compared with 3.1 and 3.2 per cent in the control herds. In most case herds, pmws developed within the first four weeks after weaning. Wasting, diarrhoea and respiratory signs were observed in 10 per cent of the weaner pigs (7 to 30 kg) in the case herds compared with 7 per cent in the control herds. The average daily gains of the weaner pigs and finisher pigs were 36 g and 52 g less in the case herds than in the control herds. By examining three weaner pigs from each herd the pmws diagnosis was confirmed by histopathology and immunohistochemistry in 78 per cent of the case herds, but at least one pmws-positive weaner pig was found in 19 of the control herds. The prevalence of pmws-positive pigs among illthriven weaner pigs was 45 per cent (101/222) in the case herds, and 12 per cent (27/222) in the control herds. Specific gross pathological findings were associated with a positive pmws diagnosis; pigs with heavy, rubber-like lungs, atonic intestines, and enlarged bronchial and inguinal lymph nodes, had a 0.7 probability of a positive pmws diagnosis by laboratory examinations. However, for illthriven pigs, this probability of having pmws was equal in the case herds and the control herds.     

Prevalence of hepatitis E virus in swine under different breeding environment and abattoir in Beijing, China

This study was to investigate the prevalence of HEV in pig herds under different breeding environment and in abattoirs located in Beijing, China. In total 638 sera samples and 114 liver samples were collected for a serological survey and a RT-PCR assay, respectively. The average prevalence rate of HEV in pig herds in Beijing suburb were 47.5-100%. Seropositive rate was 76.6% for pig herds of large-scale and 90% for family-scale farms. For sera samples collected from abattoir, 127 samples (78.4%) were found to be positive. Among four liver samples (3.5%) that positive for HEV RNA detection, two strains of HEV has been identified. the two detected HEV sequences shared 99.1% nucleotide sequence identity with each other, and 76.4-81.0%, 76.5-76.8%, 75.7-79.0% and 85.2-96.4% with related strains representing genotype 1, 2, 3, and 4, respectively. Further phylogenetic analysis revealed two HEV sequences belonged to genotype 4 and exhibited a high identity with strain JKO-ChiSai98C (95.4 and 95.7%), and with strains 87, 277 and 292 (96.1-96.4%) isolated from patients with sporadic acute hepatitis E in Beijing, China. The results of this study indicated that the prevalence of HEV in the pig herds were quite high. Additional public-health concerns might be placed on pork safety.     

猪群HEV血清抗体调查及一株新的猪HEV ORF2部分基因序列分析

戊型肝炎病毒(Hepatitis E virus,HEV)主要引起人的戊型肝炎,新近研究发现猪在病毒传播中可能发挥重要作用.本研究对我国部分省区HEV感染血清学调查,在被检的1 138份血清中,有666份(57.5%)为HEV抗体阳性,猪群抗体阳性率随着月龄增长而升高.通过RT-PCR方法从一份猪粪中扩增并克隆了HEVORF2 N端主要抗原决定区339bp基因片段,序列分析显示,该段基因与我国人群HEV基因4型毒株核苷酸序列同源性为85.9%,但氨基酸序列完全一致.这一结果提示我国猪群存在广泛的HEV感染,并在一定程度上与人群HEV毒株密切相关.     

Risk indicators for the seroprevalence of Mycoplasma hyopneumoniae, porcine influenza viruses and Aujeszky's disease virus in slaughter pigs from fattening pig herds.

Epidemiological aspects of Mycoplasma hyopneumoniae (Mh), influenza H1N1 and H3N2 viruses, and Aujeszky's disease virus (ADV) were investigated in slaughter pigs from 50 fattening pig herds. Herd factors as potential risk indicators for respiratory disease were obtained by means of a questionnaire. At slaughter, blood samples were collected from each herd, and the proportion of seropositive pigs per herd was assessed for each of these pathogens. The median herd-level seroprevalence of the agents were: Mh 88%, H1N1 100%, H3N2 60% and ADV 90%. The percentage of herds in which all investigated fattening pigs were seronegative for these agents was: Mh 0%, H1N1 0%, H3N2 12% and ADV 18%. The percentage of herds in which all investigated fattening pigs were seropositive for these agents was: Mh 8%, H1N1 71%, H3N2 22% and ADV 40%. A positive association was found between influenza H1N1 and H3N2 viruses, and a negative association between influenza H3N2 virus and ADV. There were no risk indicators for the seroprevalence of Mh. Three risk indicators were associated with the seroprevalence of influenza H1N1 virus: a fully slatted floor, an increasing number of pigs in the municipality and dry feeding. Three risk indicators were found for the seroprevalence of influenza H3N2 virus: purchase of pigs from > or = two herds, an increasing number of pigs in the municipality and natural ventilation. The seroprevalence of ADV was influenced by two risk indicators: an increasing number of pig herds in the municipality and an increasing number of pigs per pen.     

Serological survey of encephalomyocarditis virus infection in pigs in France

Samples of serum from 76 gilts, 1440 sows, 1473 piglets and 3093 finishing pigs from 96 farrow-to-finish herds were tested for antibodies to encephalomyocarditis virus (EMCV) in microtitre serum neutralisation tests employing two strains of virus, one associated with myocarditis and the other with reproductive failure. The total seroprevalence of EMCV infection was 2.48 per cent. There was no significant difference between the seroprevalence of the reproductive failure strain (1.6 per cent) and the myocardial strain (1.85 per cent). The seroprevalence was higher in the gilts (6.57 per cent) and sows (5.13 per cent) than in the piglets (1 per cent) and finishing pigs (1.84 per cent), and the highest titres were observed in the sows (1:540) and finishing pigs (1:640). In the gilts, the difference in seroprevalence between the reproductive failure strain (3.95 per cent) and the myocardial strain (5.33 per cent) was wider than in the other groups.     

Laboratory decision-making during the classical swine fever epidemic of 1997-1998 in The Netherlands

The National Reference Laboratory for classical swine fever (CSF) virus in the Netherlands examined more than two million samples for CSF virus or serum antibody during the CSF epizootic of 1997–1998. The immense amount of samples and the prevalence of border disease (BD) virus and bovine viral diarrhoea (BVD) virus infections in Dutch pig herds necessitated the diagnostic efforts of the laboratory to be focused on generating CSF specific test results throughout the eradication campaign.

Detection of 82% of the 429 outbreaks was achieved through the combined use of a direct immunofluorescence and peroxidase assay (FAT/IPA) with samples (tonsils) collected from clinically-suspected pigs. This suggests that in the majority of the outbreaks, the pigs had clinical signs that were recognised by the farmer and/or veterinarians, indicating the presence of CSF virus in a pig herd. A positive diagnosis of 74% of all the tissue samples (tonsils) collected at infected pig holdings was established by FAT. More than 140,000 heparinised blood samples were examined by virus isolation, resulting in the detection of 4.5% of the infected herds. CSF virus was isolated in approximately 29% of all the blood samples collected from pigs at infected or suspected farms.

Several serological surveys — each done within a different framework — led to the detection of 13.5% of the total number of outbreaks. The detection of CSF virus antibody in serum was carried out by semi-automated blocking ELISA. Approximately 28.5% of the sera which reacted in the ELISA were classified as CSF virus-neutralising antibody positive and 26.5% as positive for other pestiviruses following the virus neutralisation test (VNT).

We concluded that two of the CSF laboratory diagnostic methods described were determinative in the eradication campaign: first, the FAT for the screening of diseased pigs; and second, the ELISA and VNT when millions of predominantly healthy pigs needed to be screened for the presence of CSF serum antibody. Decision-making on the basis of results generated by either method can, however, be seriously hindered when samples are examined from pig herds with a high prevalence of non-CSF pestiviruses.     

A novel concept for the control of Aujeszky's disease: experiences in two vaccinated pig herds

A study was conducted to examine the usefulness of a glycoprotein I (gI)-ELISA to monitor Aujeszky's disease virus infection in two vaccinated pig herds; the gI-ELISA can differentiate between pigs infected with Aujeszky's disease virus and pigs vaccinated against Aujeszky's disease with gI-negative vaccines. The two herds had been vaccinated with gI-negative vaccines for several years. The first survey, in September 1986, revealed that approximately 10 per cent of the breeding pigs in a large multiplier herd were seropositive for antibodies to gI of Aujeszky's disease virus, and it was decided to try to eliminate the virus from the herd by gI-ELISA testing and culling of gI-seropositive pigs. A one month quarantine period for incoming stock was established, and only gI-seronegative pigs were admitted to the herd. After two rounds of testing and culling the herd appeared to be free of wild-type Aujeszky's disease virus, and neither Aujeszky's disease virus nor antibodies could be detected either in 21 sentinel pigs placed on the farm or in 347 stillborn piglets or piglets that died shortly after birth. The herd probably remained free of Aujeszky's disease virus until the end of the 27-month period of monitoring except for two of 639 breeding pigs that were unexpectedly found to be positive in the gI-ELISA in November 1987. These sows were culled. A second breeding herd was monitored for antibodies to gI of Aujeszky's disease virus for two years. The gI-seropositive sows constituted approximately 30 per cent of the herd's breeding pigs, but they were not culled.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pestivirus infections in Norway. Serological investigations in cattle, sheep and pigs.

Serum samples from 1,133 dairy cows (187 herds), 3,712 ewes (103 flocks) and 1,317 adult pigs (877 herds), were tested for neutralizing antibodies against the NADL strain of bovine virus diarrhoea virus. The prevalence rate of seropositive animals was 18.5% in cattle, 4.5% in sheep and 2.2% in pigs, such seroreactors being found in 28% of the cattle herds and 18% of the sheep flocks. In all three species the rate showed considerable herd and geographical variation. In cattle the seroreactor rate was similar in herds with normal reproduction and in 62 herds with problems of repeat breeding. Of 31 pig sera containing antibodies against the NADL strain, 27 were also positive in a neutralization test for antibodies against swine fever virus (Baker strain). However, all sera showed a higher titre of antibodies against the bovine strain than against the swine fever virus. It was concluded that the immune response of the pigs had been induced by ruminant pestivirus, and not by swine fever virus.     

Longitudinal study of hepatitis E virus infection in Spanish farrow-to-finish swine herds

Hepatitis E is a zoonotic disease and is highly prevalent in European swine livestock. There is a need to compare the infection dynamics of hepatitis E virus (HEV) between herds with the same production system and determine the percentage of animals that could arrive infected at slaughter age. Therefore, a longitudinal study was performed in six Spanish farrow-to-finish affected farms. Twenty piglets per farm were monitored from nursery to slaughter. RT-PCR and serology techniques were applied to analyze longitudinally collected sera and/or faecal samples. Liver and bile samples were also taken at the abattoir. Anti-HEV IgM were firstly detected at 7 weeks of age in 5 farms whereas at 13 weeks of age in 1 farm (farm 2). At slaughter age 50–100% of pigs had seroconverted to anti-HEV IgG in the former 5 farms whereas in the other herd only 5% of pigs were IgG seropositive (farm 2). Six out of 96 livers and 5 out of 80 biles analyzed were HEV positive at the abattoir (total percentage of infected animals: 11.5%). All these positive animals had already seroconverted except 2 pigs of farm 2. Hence, pigs can be seronegative at slaughter age being infected during the latest fattening period. Manipulation of HEV-infected livers or other organs from pigs could be considered a possible route of transmission in Spanish abattoirs. This study represents the first longitudinal survey on swine HEV infection dynamics conducted in different herds.     

Indirect fluorescence antibody studies of porcine cytomegalo virus infections in the Netherlands

Summary Sera from 683 pigs of 41 swine herds with clinical atrophic rhinitis (A R), from 477 pigs of 37 herds with no A R history, from 267 breeding sows and breeding boars for slaughtering, from 22 boars at an artifical insemination centre, and from 103 SPF pigs were tested for the presence of antibodies to porcine cytomegalo virus (PCMV). The herds examined were spread all over the Netherlands. For the presence of antibodies to PCM V the indirect fluorescence antibody test was used. To obtain the antigen, the PCMV had been grown in pig lung macrophage cultures in Petri dishes for 10-12 days. These macrophages were dropped into the wells of slides. The serum dilution 1:20 of all the 103 sera from SPF pigs were negative, but 93 per cent of the other sera were positive. No marked differences were found between swine herds with clinical atrophic rhinitis and herds with no A R history. The FA titres in both types of herds seem to be at a comparable level.     

Seroprevalence of Hepatitis E virus infection in the Irish pig population

Background

Hepatitis E is an acute viral disease of humans, occurring in explosive outbreaks in the developing world and as sporadic cases in returning travellers. Increasing recognition of indigenous transmission in Western countries suggests a zoonotic source of infection, most likely pigs. To determine if hepatitis E virus is present in Irish pigs, sera from 330 animals were examined for antibodies using a commercially available ELISA.

Findings

Antibodies were detected in 89 pigs (27%) in 13 herds (81%).

Conclusions

Hepatitis E virus is present in most Irish pig herds and in many animals within these herds.     

2010年国内部分省份猪场常见病毒性疾病的病原学调查

随着规模化养猪业的发展,传染性疾病越来越多,混合感染或多重感染十分普遍,给疾病的诊断和预防带来很大困难。本文将我们实验室2010年分别采自福建、广西、河南、上海、内蒙、浙江、江苏和山西等地发病猪场的185份病料,通过RT-PCR和PCR方法对其进行猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus,PRRSV）、猪繁殖障碍的猪瘟病毒（Classical swine fever virus,CSFV）、猪圆环病毒2（Porcine circovirus type 2,PCV2）、猪细小病毒（Porcine parvovirus,PPV）、猪伪狂犬病毒（Pseudorabies virus,PRV）、细环病毒2（Torque teno virus 2,TTV2）等病毒检测。结果表明在所检的病料中PRRSV、PCV2和TTV2的阳性率比较高,分别为49.2%、62.2%和95.1%。有些地方TTV2的阳性率高达100%;同时,还存在很普遍的PRRSV与PCV2、PRRSV与TTV2、PCV2与TTV2等混合感染,混合感染率分别为27.6%、45.4%、58.4%;以及PRRSV、PCV2与TTV2的三重感染率为24.9%。同时对部分PRRSV阳性病料的PRRSV GP5和nsp2基因分别进行测序,分析测序结果表明病料中的PRRSV的GP5和nsp2序列与PRRSV HuN4株的相应序列的亲缘关系分别在98.2%和96.2%以上,且在nsp2区域都存在30个不连续氨基酸的缺失,说明现在临床中所流行的PRRSV可能仍是与高致病性PRRSV基因型相似的病毒。通过本文可以及时了解当前养猪场的病毒性疾病的流行情况,为猪场病毒性疾病的防控提供依据。     

Pestiviral infections in sheep and pigs in Northern Ireland

Serological surveys were carried out to determine the prevalence of pestiviral infections in sheep and pigs in Northern Ireland. Sera from 918 ewes in 92 flocks from 10 regions were tested by ELISA for antibodies to border disease virus and positive results were obtained from 49 ewes (5.3 per cent) in 28 flocks (30.4 per cent). There were highly significant geographical variations in its flock prevalence ranging from 0 per cent in the Enniskillen region to 70 per cent in the Coleraine region. There was no significant association between the proportion of seropositive flocks and the presence of cattle on the farm (P = 0.583). In the positive flocks, the average rate of seroprevalence was 17.5 per cent, and the highest was 40 per cent. Comparative neutralisation studies on 14 positive sera with bovine viral diarrhoea virus type I (BVDV I) and border disease virus revealed higher titres (> or = four-fold) to BVDV I in all cases. Only one positive result was obtained when fluids from 186 aborted ovine fetuses were tested for border disease virus by ELISA. Serum samples from 680 pigs in 46 herds were tested for virus neutralising antibodies to border disease virus. Twenty sera (2.9 per cent) were cytotoxic, and only one of the remaining 660 sera gave a positive result. This sample tested negative for classical swine fever by ELISA, and comparative neutralisation studies showed that it had a four-fold higher titre to BVDV I than to border disease virus.