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1.
Polymicrobial respiratory disease in pigs 总被引：2，自引：0，他引：2
Opriessnig T Giménez-Lirola LG Halbur PG 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2011,12(2):133-148
Respiratory disease in pigs is common in modern pork production worldwide and is often referred to as porcine respiratory disease complex (PRDC). PRDC is polymicrobial in nature, and results from infection with various combinations of primary and secondary respiratory pathogens. As a true multifactorial disease, environmental conditions, population size, management strategies and pig-specific factors such as age and genetics also play critical roles in the outcome of PRDC. While non-infectious factors are important in the initiation and outcome of cases of PRDC, the focus of this review is on infectious factors only. There are a variety of viral and bacterial pathogens commonly associated with PRDC including porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), porcine circovirus type 2 (PCV2), Mycoplasma hyopneumoniae (MHYO) and Pasteurella multocida (PMULT). The pathogenesis of viral respiratory disease is typically associated with destruction of the mucocilliary apparatus and with interference and decrease of the function of pulmonary alveolar and intravascular macrophages. Bacterial pathogens often contribute to PRDC by activation of inflammation via enhanced cytokine responses. With recent advancements in pathogen detection methods, the importance of polymicrobial disease has become more evident, and identification of interactions of pathogens and their mechanisms of disease potentiation has become a topic of great interest. For example, combined infection of pigs with typically low pathogenic organisms like PCV2 and MHYO results in severe respiratory disease. Although the body of knowledge has advanced substantially in the last 15 years, much more needs to be learned about the pathogenesis and best practices for control of swine respiratory disease outbreaks caused by concurrent infection of two or more pathogens. This review discusses the latest findings on polymicrobial respiratory disease in pigs. 相似文献
2.
The aim of this study was to evaluate the vasculature in porcine circovirus type 2-infected (PCV2-infected) lungs and to identify the PCV2 subtypes involved in porcine pneumonia. Pulmonary samples from 140 pigs, 2 weeks to 7 months of age, from 36 Hungarian commercial herds with clinical signs of respiratory disease were examined for the presence of respiratory pathogens, with bacterial culture, pathologic evaluation, and immunohistochemistry for PCV2, porcine reproductive respiratory syndrome virus, and swine influenza virus. PCV2 was the most commonly identified pathogen (49 cases) among the 74 of 140 cases (53%) with respiratory pathogens. PCV2 was detected immunohistochemically in the wall of 13% to 100% of pulmonary vessels (mean, 89%) in 38 of 49 cases (78%). Detection of PCV2 antigen was positively correlated with the presence of vascular lesions (P < .001, odds ratio [OR]: 159.54). Other pathogens capable of vascular injury in swine were found in 29 of 49 of the PCV2-positive cases (59%). The probability of detecting vascular lesions in PCV2-infected lung was higher than in infection with porcine reproductive respiratory syndrome virus (P < .002, OR: 14.63), Pasteurella multocida infection (P < .001, OR: 5.75), or Streptococcus spp. infection (not significant, OR: 1.45). Sequence analysis of open reading frame 2 amplicons was possible in 6 PCV2-positive cases, from which 5 cases proved to be PCV2b subtype and 1 case, PCV2a subtype. In conclusion, PCV2 antigen was commonly colocalized with pulmonary vascular lesions in pneumonia in Hungarian swine, and PCV2b was the dominant subtype. 相似文献
3.
广西规模猪场猪呼吸道疾病综合征的病原学调查 总被引：1，自引：0，他引：1
为了解猪呼吸道疾病综合征(PRDC)在广西规模场猪群中的感染状况,采用PCR和RT-PCR方法,对2007～2009年期间采自广西13个市65个规模猪场的281份疑似PRDC感染组织样品进行了12种病原体检测。结果显示:73.85%(48/65)的猪场和71.87%(202/281)的组织样品为PRDC感染,其中,被猪繁殖与呼吸综合征病毒(PRRSV)、猪圆环病毒2型(PCV2)、猪瘟病毒(CSFV)、猪链球菌(SS)、猪伪狂犬病毒(PRV)、败血性波氏杆菌(Bb)、猪附红细胞体(E-su is)、猪流感病毒(SIV)、产毒素多杀性巴氏杆菌(T+PM)、副猪嗜血杆菌(HP)、猪细小病毒(PPV)和猪传染性胸膜肺炎放线杆菌(APP)感染(包括混合感染)的阳性样品分别占49.11%(138/281)、34.52%(97/281)、9.60%(27/281)、8.19%(23/281)、6.41%(18/281)、6.41%(18/281)、6.05%(17/281)、6.14%(15/281)、4.63%(13/281)、3.91%(11/281)、0.36%(1/281)和0.00%(0/281);单纯感染占28.11%(79/281);混和感染占43.77%(123/281)。二重、三重和四重混合感染分别占28.11%(79/281)、12.46%(35/281)和3.20%(9/281)。其中,以PRRSV+PCV2(+其他)混合感染形式较多见,占所有混合感染样品的52.03%(64/123)。细菌性病原体感染样品占20.28%(57/281),其中19.22%(54/281)为混合感染。可见:广西地区规模猪场普遍存在PRDC感染,其中PRRSV和PCV2是引起PRDC的主要病原;感染类型复杂多样,以PRRSV+PCV2(+其他)混合感染最为常见。 相似文献
4.
The role of swine torque teno sus viruses (TTSuVs) as co-factors in disease syndromes involving porcine circovirus strain 2 (PCV2) and porcine reproductive and respiratory disease syndrome virus (PRRSV) has been a debatable subject. In this study, the prevalence of TTSuVs in Iowa, the leading pork producing state in the U.S., was estimated by a duplex PCR. The PCR is capable of simultaneously detecting both teno sus viruses 1 and 2 (TTSuV1 and 2). Based on an analysis of 300 random samples representing six major geographical regions of the state, the overall prevalence rates for TTSuV1 and 2 were 47.34% and 24.67% respectively while the combined prevalence rate was 52.33%. The epidemiological association of TTSuV1 and 2 with the common etiological agents of the porcine respiratory disease complex (PRDC) namely porcine PRRSV, PCV2, Mycoplasma hyopneumoniae and swine influenza virus (SIV) was estimated in lung tissue derived from 45 pigs showing clinical signs of PRDC. Notably, 86.67% of the PRDC-suspect samples were positive for TTSuV1 in comparison to the baseline population prevalence rate of 47.34%. However, the prevalence of TTSuV2 (26.67%) was not significantly different. TTSuV1 was detected in 80.00%, 81.81%, 75.00% and 77.78% of the PRRSV, SIV, M. hyopneumoniae and PCV2 positive PRDC-suspect samples respectively. Our results indicate that TTSuV1 is strongly associated with clinical PRDC and support the hypothesis that TTSuVs might function as co-factors in PRDC. Further studies to define their possible role in the pathogenesis of swine respiratory diseases are warranted. 相似文献
5.
Porcine respiratory disease complex after the introduction of H1N1/2009 influenza virus in Brazil 
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下载免费PDF全文 R. R. Rech D. Gava M. C. Silva L. T. Fernandes V. Haach J. R. Ciacci‐Zanella R. Schaefer 《Zoonoses and public health》2018,65(1):e155-e161
From 2009 to 2015, 74 lungs from suckling (6.8%), nursing (70.3%), fattening (20.3%) pigs and pregnant sows (2.7%) with respiratory signs from pig farms in Southern Brazil were submitted to a diagnostic laboratory for necropsy and/or histologic examination and screening for respiratory agents by RT‐qPCR, immunohistochemistry (IHC), virus isolation (VI) and subtyping for influenza A virus (IAV), IHC and nested PCR for Mycoplasma hyopneumoniae (Mhyo), PCR for porcine circovirus 2 (PCV2), RT‐qPCR for porcine reproductive and respiratory syndrome virus (PRRSV) and bacterial culture. All lung samples were positive for IAV using RT‐qPCR. Seventy‐two lungs had histologic lesions associated with acute to subacute IAV infection characterized by necrotizing bronchiolitis/bronchitis or bronchointerstitial pneumonia with lymphocytic peribronchiolitis and bronchiolar/bronchial hyperplasia, respectively. Forty‐nine lungs (66.2%) were positive by IHC for IAV nucleoprotein. The H1N1/2009 was the most common subtype and the only IAV detected in 58.1% of lungs, followed by H1N2 (9.5%) and H3N2 (6.8%). Coinfection of IAV and Mhyo was seen in 23 (31%) cases. Although 14.9% of the lungs were positive for PCV2 using PCR, no suggestive lesions of PCV2 disease were observed. Porcine reproductive and respiratory syndrome virus (PRRSV) was not detected, consistent with the PRRS‐free status of Brazil. Secondary bacterial infections (8/38) were associated with suppurative bronchopneumonia and/or pleuritis. Primary IAV infection with Mhyo coinfection was the most common agents found in porcine respiratory disease complex (PRDC) in pigs in Southern Brazil. 相似文献
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7.
Lester J. Pérez Heidy Díaz de Arce Maria I. Percedo Patricia Domínguez Maria T. Frías 《Research in veterinary science》2010,88(3):528-530
To obtain information about the porcine circovirus type 2 (PCV2) infection status of pigs in Cuba and the probable association of PCV2 with other porcine viruses, tissue samples collected from ill pigs were evaluated using polymerase chain reaction (PCR). The PCR analysis showed that 67.7% of the samples (23/34) from seven swine herds of six different geographic regions were detected to be positive for PCV2. Ten of the 23 PCV2 positive samples (43.5%) shown a concurrent infection with porcine parvovirus (PPV) and 17 of 23 PCV2 positive samples (73.9%) exhibited a concomitant infection with classical swine fever virus (CSFV). This study is the first report of PCV2 infecting pigs with different clinical conditions in Cuban swine herds and provides evidence of PCV2 co-infection with PPV and CSFV in the field. 相似文献
8.
猪呼吸道疾病综合征（PRDC）在养猪业中广泛流行,发病原因复杂,由多种细菌、病毒、寄生虫及环境应激等因素共同引发,普遍造成猪生长迟缓和猪肉品质下降,还有相当比例的病猪死亡,严重影响养猪业的发展。胸膜肺炎放线杆菌（APP）、副猪嗜血杆菌（Hps）、链球菌（SS）是常见的细菌性病原,而猪繁殖与呼吸障碍综合征病毒（PRRSV）、猪圆环病毒2型（PCV2）、伪狂犬病毒（PRV）是常见的病毒性病原,合理用药防治PRDC十分关键。头孢喹肟、氟苯尼考及加米霉素等抗生素因抗菌谱广、抗菌活性强、在猪体内药代动力学特征优良等优点被广泛用于防控细菌性感染的猪呼吸道疾病。对于病毒性感染的猪呼吸道疾病,常用的抗病毒药物有细胞因子及中药,尤其是中药,不仅可以抗病毒还可增强机体免疫力,应用前景非常广阔。文章系统地阐述了上述抗菌药物的抗菌机理、药效学及药动学,详细介绍了上述抗病毒药物的抗病毒机理及其在病毒性猪呼吸道疾病上的应用,以期为合理用药防控PRDC提供一定的建议。 相似文献
9.
DENG Tongwei XUE Yanan LU Jianzhou XIA Yanxun CHEN Lulu GUO Yiwen PENG Liming JIANG Zenghai QIAO Hongxing XU Yaohui ZHANG Xiaozhan 《中国畜牧兽医》2007,47(10):3401-3409
To identify the causative agent of porcine respiratory disease complex (PRDC) occurred at a pig farm in Kaifeng city,Henan province,we identified the potential causative bacteria of the morbid nursing piglets by bacterial test and drug sensitivity test of the clinical samples (lung,liver and spleen),and detected the common potential pathogens causing PRDC diseases by PCR and RT-PCR assays,including porcine reproductive and respiratory syndrome virus (PRRSV),porcine circovirus type 2 (PCV2),swine influenza virus (SIV),pseudorabies virus (PRV),classical swine fever virus (CSFV) and Mycoplasma hyopneumoniae (Mhp),and then sequcing and phylogenetic analysis of the structural gene of positive causative pathogens were carried out.The results showed that a Haemophilus parasuis (Hps) strain were isolated and identified by the observation of bacterial morphology and satellite phenomenon,and the sequence analysis of 16S rRNA gene.The drug sensitivity test showed that the Hps strain was sensitive to ampicillin,amoxicillin-clavulanic acid,ceftiofur and tetracycline.Meanwhile,PCR and RT-PCR assays indicated that all the samples were positive for PRRSV and PCV2,and named the involved strain as PRRSV/HN-2019 and PCV2/HN11-2019,respectively.Sequencing and phylogenetic analysis of the ORF5 gene of the newly identified PRRSV revealed that the PRRSV/HN-2019 strain was closely related to the NADC30-like strains and grouped into NADC30-like genotype clade.And cap gene of the newly identified PCV2 strain the PCV2/HN11-2019 strain was closely related to the PCV-2d strains and grouped into PCV-2d genotype clade.In conclusion,this study demonstrated that the morbid piglets were co-infected with PRRSV,PCV2 and Hps,which provided a basis for the development of effective control strategies in the pig farm. 相似文献
10.
华南地区猪圆环病毒和猪繁殖与呼吸综合征病毒检测分析 总被引：1，自引：0，他引：1
为了解华南地区猪圆环病毒及猪繁殖与呼吸综合征病毒的最新流行情况,采集了华南地区11个规模猪场各饲养阶段猪血清807份,用套式PCR(nPCR)检测猪圆环病毒1型(PCV-1)和猪圆环病毒2型(PCV-2);采集了若干猪场2010年1月至2011年8月期间有咳嗽、喘气、消瘦及疑似PDNS等临床症状的猪血清312份,以及无临床症状猪血清104份,以nPCR检测PCV-2,以一步法反转录PCR(RT-PCR)检测猪繁殖与呼吸综合征病毒。结果发现,所调查的11个规模猪场中只有5个检出PCV-1,所有猪场均检出PCV-2。PCV-2阳性率为30.61%,而PCV-1阳性率仅为4.21%;经产母猪和7周龄以上保育猪PCV阳性率最高;有临床症状的猪血清PCV-2阳性率为58.65%,PRRSV阳性率为37.82%,PCV-2阳性猪群中有39.89%的猪同时感染PRRSV;有症状猪群7月～9月的PCV-2感染率最高,而1月～3月最低;无临床症状猪血清PCV-2阳性率为27.9%,PRRSV阳性率为0.96%,PCV-2与PRRSV无混合感染。证明PCV尤其是PCV-2在华南地区仍广泛传播并流行,而且PCV-2与PRRSV混合感染致病情况较多。PCV-2的感染率与季节有一定的相关性,种猪带毒情况严重。 相似文献
11.
为确定河南开封某猪场发生猪呼吸系统疾病综合征（PRDC）的病原,本研究无菌采集病死保育猪肺脏、心脏和脾脏等组织样品,进行细菌学检验和药敏试验,通过PCR/RT-PCR检测样品中猪繁殖与呼吸综合征病毒（PRRSV）、猪圆环病毒2型（PCV2）、猪流感病毒（SIV）、猪伪狂犬病病毒（PRV）、猪瘟病毒（CSFV）和猪肺炎支原体（Mhp）等病原,并对核酸阳性病毒性病原的抗原结构基因进行测序和遗传演化分析。结果表明,通过细菌分离培养、形态观察、卫星现象观察和16S rRNA基因鉴定,从病死保育猪体内分离鉴定出1株副猪嗜血杆菌（Hps）,药敏实验表明该菌株对对氨苄西林、阿莫西林克拉维酸、头孢噻呋和四环素几种药物敏感。核酸检测PRRSV和PCV2核酸阳性,分别命名为PRRSV/HN-2019和PCV2/HN11-2019;进一步对PRRSV/HN-2019和PCV2/HN11-2019的结构基因分析发现,PRRSV/HN-2019与与NADC30分支的毒株亲缘关系较近,属于NADC30-like毒株;PCV2/HN11-2019与PCV-2d分支的毒株亲缘关系较近,属于PCV-2d分支。综上所述,本研究确定该猪场存在PRRSV、PCV2和Hps的混合感染,为该猪场下一步的PRDC有效防控提供了参考依据。 相似文献
12.
Case-control study on the association of porcine circovirus type 2 and other swine viral pathogens with postweaning multisystemic wasting syndrome. 总被引：19，自引：0，他引：19
Roman M Pogranichniy Kyoung-Jin Yoon Perry A Harms Steven D Sorden Michael Daniels 《Journal of veterinary diagnostic investigation》2002,14(6):449-456
A field-based case-control study was conducted to assess the strength of association of porcine circovirus type 2 (PCV2) and some major swine viruses with postweaning multisystemic wasting syndrome (PMWS). Cases were defined as individual pigs with a clinical history of progressive weight loss and histopathological lesions characteristic of PMWS. Controls were pigs without clinical signs and histopathological lesions typical of PMWS. A total of 31 cases and 56 controls was identified from diagnostic submissions. Serum and various tissues were collected from all animals and assayed for PCV, porcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus, porcine enterovirus types 1-3, swine influenza virus, porcine respiratory coronavirus, transmissible gastroenteritis virus, porcine endogenous retrovirus, porcine lymphotropic herpesvirus type 1, and bovine viral diarrhea virus. The proportion of case and control pigs positive for each virus was determined and statistically compared for determining the strength of the association that each virus had with PMWS individually or in combinations. Porcine circovirus type 2 had the strongest association (OR = 9.3, P = 0.006) with PMWS among the viruses tested for. Risk for PWMS was much higher (OR = 31.2, P = 0.0009) if the animal was concurrently infected with PCV2 and PRRSV, suggesting that development of PMWS may be enhanced by cofactor(s). Because PCV2 was also found in 62.5% of the controls, PCV2 from 5 cases and 4 controls were selected and genetically compared. No significant genetic difference was observed between PCV2 from PMWS and control pigs. 相似文献
13.
Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are pathogens, which can significantly affect the swine industry worldwide. Field surveys suggest that simultaneous PRRSV and PCV2 infection is common in pigs. The objective of this study was to measure the changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with PRRSV and PCV2, in order to analyze the synergistic influence of co-infection on the immune system. Changes in peripheral blood leukocyte subpopulations were systematically measured by flow cytometry (FCM). The levels of antibodies to PRRSV and PCV2 were detected by indirect Enzyme-Linked ImmunoSorbent Assay (ELISA) and the indirect fluorescent antibody test (IFA), respectively. Serum viral loads were measured using real-time PCR. The results showed that piglets co-infected with PRRSV and PCV2 exhibited slower generation and lower levels of antibodies to PRRSV and PCV2, and increased amounts and a prolonged presence of both PRRSV and PCV2 in serum, in comparison to the piglets infected with either virus alone. The major finding in our study was that the total and differential leukocyte counts, including white blood cells (WBCs), monocytes, granulocytes and lymphocytes (T, B and NK cells, as well as T-cell subpopulations), dramatically decreased early during co-infection with PRRSV and PCV2 for about two weeks, in contrast with animals singly infected with either PRRSV or PCV2. These results suggest that PRRSV and PCV2 co-infection results in a synergistic decrease in immune cells in the peripheral blood of piglets. These data contribute to the understanding of the immunosuppressive effects resulting from PRRSV and PCV2 co-infection in pigs. 相似文献
14.
A retrospective study on pig lung tissues from 60 cases of proliferative and necrotizing pneumonia (PNP) was performed to determine the presence of porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), and porcine circovirus type 2 (PCV2) in these lesions. Cases selected included 30 cases diagnosed between 1988 and 1992 and 30 cases diagnosed between 1997 and 2001. In each group of 30 cases, 10 were from suckling piglets, whereas the other 20 were from postweaned animals representing either nursery or grower-finisher pigs. Immunohistochemistry using a monoclonal antibody to influenza virus type A was used to determine the presence of SIV, and in situ hybridization was used for the detection of PRRSV and PCV2 nucleic acids. PRRSV was detected in 55 of the 60 cases examined (92%), PCV2 in 25 cases (42%), and SIV in only 1 case (2%). In 30 cases (50%), PRRSV was the only virus detected, whereas in 25 other cases (42%), a combination of PRRSV and PCV2 could be detected in the lungs with PNP lesions. PCV2 could not be detected in the lungs of suckling pigs with PNP. All PCV2-positive cases were found in postweaned pigs and were always in combination with PRRSV. In this latter age group, PCV2 was detected in 63% of the cases (25/40). Data from our study indicate that SIV is rarely identified in PNP and that PCV2 infection is not essential for the development of PNP lesions. The results of the present study demonstrate that PRRSV is consistently and predominantly associated with PNP and should be considered the key etiologic agent for the condition. 相似文献
15.
Postweaning multisystemic wasting syndrome of pigs in Korea: prevalence, microscopic lesions and coexisting microorganisms 总被引：10，自引：0，他引：10
Kim J Chung HK Jung T Cho WS Choi C Chae C 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2002,64(1):57-62
A retrospective study was performed on natural cases of postweaning multisystemic wasting syndrome (PMWS), recorded from January 1999 to December 2000, to determine the prevalence, microscopic lesions, and other coexisting pathogens associated with PMWS. PMWS is diagnosed based on three criteria: the presence of clinical signs (retardation of growth), characteristic microscopic lesions (granulomatous inflammation and inclusion body), and the presence of porcine circovirus (PCV)-2 within these lesions. One hundred and thirty three (8.1%) of the 1634 pigs submitted from 1243 pig farms were diagnosed for PMWS. The affected pigs were from 25 to 120 days old, the majority (78 cases, 58.6%) being 60 to 80 days old. PMWS occurred each month during the two-year study period, but the incidence peaked in May (38 cases, 28.6%), followed by April (18 cases, 13.5%) and June (13 cases, 9.8%). The most consistent and characteristic lesions were multifocal, granulomatous inflammation in lymph nodes, liver and spleen, characterized by infiltration of epithelioid macrophages and multinucleated giant cells. The majority of cases (113 cases, 85.0%) was dual infection with other pathogens. The combination of PCV-2 and Hemophilus parasuis (43 cases, 32.3%) was shown to be the most prevalent followed by PCV-2 and porcine reproductive and respiratory syndrome virus (39 cases, 29.3%). The consistent presence of PCV-2, but lower prevalence of other viral and bacterial pathogens in all pigs examined with PMWS, has led to the speculation that PCV-2 is the etiological agent causing PMWS. 相似文献
16.
Immunology of the porcine respiratory disease complex. 总被引：1，自引：0，他引：1
E L Thacker 《Veterinary Clinics of North America: Food Animal Practice》2001,17(3):551-565
PRDC is a multifactorial respiratory syndrome that includes several respiratory pathogens. As can be observed in this article, although the pathogenesis of some of the respiratory pathogens of pigs is fairly well defined, the host response and the immune response necessary to control the pathogen often remain unclear. As our ability to evaluate the porcine immune system and its ability to respond to disease improves, the knowledge of how each of these respiratory pathogens alter and evade the immune system will increase. The pathogens most commonly isolated from pigs with clinical signs of PRDC either infect the cells of the immune system or induce significant immunopathology. Thus, PRRSV and M. hyopneumoniae, the two most common pathogens associated with PRDC, alter the ability of the respiratory immune system to respond to their presence and the presence of other pathogens. By changing the respiratory immune system, these two common pathogens increase the susceptibility to the many other pathogens associated with PRDC. As we learn more about the pathogens of the respiratory system, their interactions with each other, and the mechanisms by which they modulate the immune system, our ability to develop effective control measures will improve. 相似文献
17.
Dorr PM Baker RB Almond GW Wayne SR Gebreyes WA 《Journal of the American Veterinary Medical Association》2007,230(2):244-250
OBJECTIVE: To identify important pathogens and characterize their serologic and pathologic effects in porcine circovirus type 2 (PCV2)-infected pigs in relation to pig age and type of swine production system. DESIGN: Cross-sectional study. ANIMALS: 583 conventionally reared pigs. PROCEDURES: 3- (n = 157), 9- (149), 16- (152), and 24-week-old (125) pigs from 41 different 1-, 2-, and 3-site production systems (5 pigs/age group/farm) were euthanized and necropsied. Pigs with and without PCV2 infection were identified (via PCR assay); infection with and serologic responses to other pathogens and pathologic changes in various tissues (including lungs) were assessed. Logistic regression models were constructed for effects overall and within each age group and type of production system. RESULTS: Compared with PCV2-negative pigs, PCV2-positive pigs were more likely to have swine influenza virus (SIV) type A and Mycoplasma hyopneumoniae infections and sample-to-positive (S:P) ratios for SIV H1N1 from 0.50 to 0.99; also, PCV2-positive pigs had higher serum anti-porcine reproductive and respiratory syndrome virus (PRRSV) antibody titers and more severe lung tissue damage. Infection with SIV (but lower SIV H1N1 S:P ratio) was more likely in 3-week-old PCV2-positive pigs and evidence of systemic disease was greater in 16-week-old PCV2-positive pigs than in their PCV2-negative counterparts. By site type, associations of coinfections and disease effects between PCV2-positive and -negative pigs were greatest in 3-site production systems. CONCLUSIONS AND CLINICAL RELEVANCE: In PCV2-positive pigs, coinfections with SIV, M. hyopneumoniae, and PRRSV are important, having the greatest effect in the early to late nursery phase and in 3-site production systems. 相似文献
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猪呼吸道疾病综合征是一种由病毒、细菌、环境应激和猪体免疫力低下等多因素相互作用引起的呼吸道疾病。2009年2～4月,上海农场某猪场一批育肥猪出现疑似病例,表现为食欲下降,咳嗽,呼吸困难,生长缓慢和料肉比降低。本研究在流行病学调查的基础上,剖检8头病猪观察其病理变化,主要表现为肺脏弥慢性实变,弹性降低,间质增宽,有的水肿、气肿,或纤维素性胸膜肺炎。病原检测结果显示,该发病猪群主要病原为猪繁殖与呼吸综合征病毒、猪圆环病毒2型和副猪嗜血杆菌。本研究为猪呼吸道疾病综合征的防治提供了依据。 相似文献
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Giammarioli M Pellegrini C Casciari C De Mia GM 《Veterinary research communications》2008,32(3):255-262