【作者】 刘翠权；

【导师】 陆承平； 刘棋；

【作者基本信息】 南京农业大学 ， 兽医， 2011， 博士

【摘要】 猪呼吸道疾病综合征(PRDC)是一种多因子疾病,它是由病毒、细菌、支原体、寄生虫、不良的饲养管理条件及易感猪群等综合因素相互作用引起的疾病综合症。为了解该病在广西猪群中的感染状况,主要采用PCR和RT-PCR方法,结合细菌分离鉴定,2007年5月至2009年5月,对广西14个市395个规模猪场的1686份组织样品分别进行了12种病原检测。结果显示：292个规模猪场和1212份样品为PRDC阳性,猪场和组织样品的阳性率分别为73.92%(292/395)和71.89%(1212/1686)。其中,单独或者混合感染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)、支气管败血波氏杆菌(Bb)、猪流感病毒(SIV)、猪附红细胞体(E-suis)、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)的阳性样品分别为51.36%(866/1686)、36.54%(616/1686)、10.91%(184/1686)、9.19%(155/1686)、6.76%(114/1686)、6.64%(112/1686)、5.81%(98/1686)、5.63%(95/1686)、4.45%(75/1686)、3.91%(66/1686)、0.59%(10/1686)和0(0/1686)。1病原学分析从感染的类型看,在1212份阳性样品中,单独感染的样品351份,占28.96%(351/1212)；混合感染的样品861份,占71.04%(861/1212)。从混合感染的类型看,在861份混合感染阳性样品中,二重混合感染597份、三重混合感染210份、四重混合感染54份,分别占69.34%(597/861)、24.39%(210/861)和6.27%(54/861)。从混合感染的微生物种类看,在861份混合感染阳性样品中,“病毒与病毒”混合感染的样品460份、“病毒与细菌”混合感染的样品401份,分别占53.43%(460/861)和46.57%(401/861)。从感染的优势病原分析,PRRSV和/或PCV2感染的样品1054份,占1212份阳性样品的86.96%。其中,"PRRSV+PCV2(+其它病原)”混合感染的样品428份,占所有861份混合感染样品的49.71%。结果表明：广西规模猪场普遍存在PRDC, PRRSV、PCV2是引起PRDC的主要病原；感染类型复杂多样,混合感染相当普遍,以"PRRSV+PCV2(+其它病原)”混合感染最为常见。2病理组织学观察在病原学调查的基础上,对560个PRDC病例的心、肝、肺、肾、脾、淋巴结等组织器官进行石蜡包埋、切片、H.E染色,光学显微镜下观察其病理组织学特征。560个中的500个(占89.3%),其中,PRRSV单独感染病例166个、PRV单独感染病例22个、PRRSV+PCV2混合感染病例247个、PCV2+PRV混合感染病例38个、PRRSV+E-suis感染病例21个、PRRSV+CSFV+PCV2+HP感染病例6个,其心、肝、肺、肾、脾、淋巴结等组织器官的病理组织学变化呈现以下特点：PRRSV单独感染的病例,肺主要表现为间质性肺炎,肾表现为肾小球肾炎,淋巴结表现为急性增生性淋巴结炎,肝脏表现为变质性肝炎,心肌表现为变质性心肌炎,脾表现为脾小体体积缩小、坏死,红髓区内出血,淋巴细胞减少；PRRSV和/或PCV2混合感染其他病毒或继发细菌感染时,病变更加典型,组织细胞发生变性甚至坏死。系统的病理组织学观察为进一步形成PRDC的病理组织学诊断技术规范提供重要参考依据。3防控措施2009年5月开始,对15个试验猪场采取综合防控措施。这些措施主要包括：对必须进入猪场的人员、车辆、物品随时进行消毒,对猪舍地板、墙壁、天花板、空气、用具等定期进行消毒；做好PRRSV、CSFV、PRV、SIV、PCV2等PRDC原发性病原的免疫和监测,对抗体水平不合格的及时进行强化免疫;做好环境虫鼠蚊蝇等生物灾害防范和通风、温度、湿度控制；加强饲养管理,做到全进全出、养殖密度合理、营养均衡；尽可能减少猪群转栏、混群、免疫次数,净化养殖周边环境,减少应激；对病猪及时隔离并投喂敏感药物,防止继发感染；对死猪及其污染的物品及时进行无害化处理和消毒。重点措施是消毒、监测和对病死及带毒猪的隔离、淘汰、无害化处理,主要内容包括：对必须进入猪场的人员、车辆和物品随时进行消毒；对产房、保育猪舍、生产育肥猪舍的地板、墙壁、天花板、用具等分别进行2次/周、1次/周、2次/月的常规消毒,空栏后进猪前进行2次全面消毒；对产房、保育猪舍的空气在空栏后进猪前进行1次密闭熏蒸消毒；对猪舍外环境进行2次/月的消毒；对病猪和带毒猪及时隔离、淘汰,对死猪及其污染的物品及时进行无害化处理和消毒。4防控效果采取综合防控措施后,猪瘟的免疫抗体合格率明显提高,猪瘟、猪繁殖与呼吸综合征、猪伪狂犬病、猪圆环病毒2型感染和猪流感的病原学监测的平均阳性率均不同程度地下降。2009年5月至2010年6月,共监测15个规模猪场血清样品16974份、病原学样品1589份。其中,猪瘟免疫抗体的平均合格率由试验前的91.18%提升到试验后的95.90%,病原学样品的平均阳性率由8.55%下降到6.04%；猪繁殖与呼吸综合征免疫抗体的平均阳性率由86.46%提升到88.11%,病原学样品的平均阳性率由15.80%下降到13.15%；猪圆环病毒2型病原学样品的平均阳性率由26.61%下降到22.28%；猪伪狂犬病gE抗体的平均阳性率由5.53%下降到4.51%,病原学样品的平均阳性率由6.43%下降到5.16%；猪流感感染抗体的平均阳性率由5.51%下降到5.30%,病原学样品的平均阳性率由637%下降到4.97%。生猪的死亡率总体趋于下降。15个猪场的总体平均死亡率由试验实施1～2月的8.28%下降到实施11～12月的7.24%,总体下降了1.04个百分点。种猪的繁殖性能和仔猪的存活率显著提高,仔猪的平均死亡率明显下降。其中,每头长白母猪年平均提供活仔数由20.73头提高到21.57头,提高了0.84头；仔猪的平均死亡率由8.54%下降到6.86%,下降了1.68个百分点。每头杜洛克母猪年平均提供活仔数由18.95头提高到19.23头,提高了0.28头；仔猪的平均死亡率由7.44%下降到6.55%,下降了0.89个百分点。每头大约克母猪年平均提供活仔数由19.97头提高到20.54头,提高了0.57头；仔猪的平均死亡率由7.42%下降到6.39%,下降了1.03个百分点。仔猪的生长性能大幅度提高。其中,长白仔猪达到30kg和100kg的平均日龄分别提前了2.1天和3.3天,30～100kg平均日增重提高了30.1g,保育猪和育肥猪的料肉比分别降低了0.063和0.098。杜洛克仔猪达到30kg和100kg的平均日龄分别提前了2.1天和3.9天,30～100kg平均日增重提高了24.6g,保育猪和育肥猪的料肉比分别降低了0.029和0.089。大约克仔猪达到30kg和100kg的平均日龄分别提前了1.9天和3.6天,30～100kg平均日增重提高了21.5g,保育猪和育肥猪的料肉比分别降低了0.023和0.056。2009年5月至2010年6月,采取上述综合措施后,15个规模猪场的主要疫病防控效果显著,生猪发病减少了,死亡率降低了,猪群的免疫抗体水平、种猪的繁殖性能、仔猪的死亡率和生长性能等各项指标均发生了明显改善,取得了良好的经济效益和社会效益。更多还原

【Abstract】 Porcine respiratory disease complex (PRDC) is a multi-factorial respiratory syndrome and is the result of a combination of viruses, bacteria, mycoplasmas, parasites, bad breeding administration conditions, susceptible pig population and so on. To understand infectious status of PRDC in pig population in Guangxi,1686 tissue samples collected from 395 large scale pig farms scattered in 14 districts were tested for 12 PRDC-associated pathogens in this study using PCR, RT-PCR, and bacteria isolation assay from May 2007 to May 2009. Results showed that 292 farms and 1212 samples were all positive for PRDC. The PRDC positive rate of farm and sample were 73.92%(292/395) and 71.89%(1212/1686), respectively. Particularly, single or mixed infection positive rate of porcine reproduce and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), classical swine fever virus (CSFV), streptococcus suis (SS), pseudorabies virus (PRV), bordetella bronchiseptica (BB), swine influenza virus (SIV), eperythrozoon suis (ES), toxigenic pasteurella multocida (T+PM), haemophilus parasuis (HP), porcine parvovirus (PPV) and actinobacillus pleuropneumoniae (APP) were 51.36%(866/1686),36.54%(616/1686), 10.91%(184/1686),9.19%(155/1686),6.76%(114/1686),6.64%(112/1686),5.81% (98/1686),5.63%(95/1686),4.45%(75/1686),3.91%(66/1686),0.59%(10/1686) and 0 (0/1686), respectively.Aetiological Analysis In 1212 PRDC positive samples, only 351 samples were found to be single infection with a proportion of 28.96%, while the other 861 samples (accounting for 71.04%) were mixed infection. Furthermore, among these 861 mixed infection samples, the sample number of dual infection type, triple infection type, and quadruple infection type were 597 (69.34%),210 (24.39%) and 54 (6.27%), respectively. Microorganism co-infection analysis showed that 460 out of 861 samples were "virus and virus" mixed infection with a proportion of 53.43%, and the other 401 samples were "virus and bacterium" mixed infection holding the remaining 46.57%. Analysis on dominating pathogen of PRDC showed that 1054 samples were infected with PRRSV and/or PCV2 accounting for 86.96%of 1212 PRDC positive samples, and the number of "PRRSV+ PCV2 (+other pathogens)" co-infection sample was 428, which shares 49.71%in 861 mixed infection samples. The results suggest that large scale pig farms in Guangxi generally suffered from the PRDC characterized with major pathogen of PRRSV and PCV2, type of infection was complicated and various, and mixed infection was quite common, of which the "PRRSV+PCV2 (+other pathogens)" co-infection was the most common one.Histopatbological Observation Basing on the aetiological investigation, tissue or organ specimens of heart, liver, lung, kidney, spleen, and lymph node collected from 560 PRDC cases were fixed, paraffin embedded, H.E stained, and then histopathological features were observed via optical microscope. Histopathological features of 500 out of 560 PRDC cases were typic and similar. Among the 500 PRDC cases, the cases of single infection with PRRSV and PRV were 166 and 22, respectively; while the cases of co-infection with PRRSV+PCV2, PCV2+PRV, PRRSV+E-suis and PRRSV+CSFV+PCV2 +HP were 247,38,21 and 6, respectively. Specific histopathological features of 500 cases were listed as follows:As to single infection with PRRSV case, lung tissues generally developed into interstitial pneumonia lesions; kidney tissues developed glomerulonephritis lesions; lymph node expressed proliferative lesions of acute lymphadenitis; liver tissues suffered from deterioration hepatitis lesions; cardiac muscle generally showed metamorphic myocarditis lesions; and spleen showed lesions of splenic corpuscle volume reduction or necrosis, red pulp region hemorrhage and lymphopenia. As for cases of PRRSV and/or PCV2 co-infection with other viruses or secondary infection with bacteria, histological lesions became more typical, and many tissues and cells developed degeneration, even necrosis. Above results of systematic histopathological observation and description furthermore provided important supportive reference materials for establishment of histopathological technology standard for diagnosis on PRDC.Control and Prevention Measures Beginning in May 2009, a series of disease control and prevention measures in order to strengthen bio-safety and breeding management were established and implemented in 15 experimental pig farms. These measures mainly included:strict disinfection and access control on personnel, vehicles and items; termly disinfection of floor, wall, ceiling, air and tools involved in swine feeding; appropriate vaccination programme and monitoring of primary pathogens of PRRSV. CSFV, PRV, SIV and PCV2; prevention of environmental pests, mice, mosquitoes, flies and other biological disasters; control on ventilation, temperature and humidity; better breeding administration measures such as empty pit, cleaning, disinfection, all-in/all-out, reasonable stocking density, balanced nutrition, no mixing of batches, no mixing in-between compartments, stress minimization, prompt isolation of sick pigs from healthy population and treatment to prevent secondary infection, and strict free-pollution disposal and disinfection of dead pigs and all the polluted items.The most important measures were disinfection, surveillance and free-pollution disposal. The detailed measures were listed as follows:strict disinfection of personnel, vehicles and items that went into the pig farms; routine disinfection of floor, wall, ceiling and tools of farrowing house, nursing house and fattening house 2 times/week,1 times/week and 2 times/month, respectively, and 2 times disinfection for all houses after all pigs out and before new pig population in; fumigated disinfection of air of farrowing house and nursing house 1 times after all pigs out and before new pig population in; disinfection of outside environment of the pig farm 2 times/month; isolation and elimination of sick pigs, and strict free-pollution disposal and disinfection of dead pigs and all the polluted items in time.Control and Prevention Effects Pass rates of immune antibodies against CSFV in these experimental farms increased significantly, accompanied with positive rates of major pathogens drastically decreased. From May 2009 to June 2010, Detection results of 16974 sera and 1589 tissue samples from 15 pig farms showed that the average pass rate of immune antibody against CSFV jumped from 91.18% of pre-experiment to 95.90% of post-experiment, while average CSFV positive rate decreased from 8.55% to 6.04%; in addition, average pass rate of PRRSV antibody climbed from 86.46% to 88.11%, with the decline from 15.80% to 13.15% in average PRRSV positive rate; average positive rate of PCV2 fell from 26.61% to 22.28% as well; furthermore, average positive rate of PRV gE specific antibody in sera and PRV in tissue samples dropped from 5.53% and 6.43%, respectively, to 4.51% and 5.16%; similarly, average positive rate of SIV infectious antibody in serum samples and virus in tissue samples sank from 5.51% and 6.37%, respectively, to 5.30% and 4.97%.Pig mortality declined generally. Average mortality of 15 farms decreased from 8.28% one-two months after experiment to 7.24% eleven-twelve months after experiment.Reproduce performance of breeding pig and survival rate of piglet promoted significantly. For example, average number of survival piglet per year of each Landrace sow increased by 0.84 from 20.73 to 21.57; average mortality of Landrace piglet decreased from 8.54% to 6.86%. Similarly, average number of survival piglet per year of each Duroc sow rise by 0.28 from 18.95 to 19.23; average mortality of Duroc piglet decreased from 7.44% to 6.55%. In large Yorkshire groups, average number of survival piglet per year of each sow climbed 0.57 from 19.97 to 20.54; average mortality of piglet decreased from 7.42%to 6.39%.Growth performance of piglet upgraded greatly. For example, the age to 30kg (AGE30) and the age to 100kg (AGE100) of Landrace piglet shortened 2.1 days and 3.3 days, respectively, the average daily gain from 30kg to 100kg (ADG) increased 30. 1g, the feed conversion ratios (FCRs) of nursery pig and fattening pig decreased 0.063 and 0.098, respectively. The AGE30 and AGE100 of Duroc piglet reduced 2.1 days and 3.9 days, ADG increased 24.6g, FCRs of nursery pig and fattening pig fell 0.029 and 0.089, respectively. Similarly, the AGE30 and AGE100 of Yorkshire piglet decreased 1.9 days and 3.6 days, ADG added 21.5g, FCRs of nursery pig and fattening pig dropped 0.023 and 0.056, respectively.In sum, from May 2009 to June 2010, after the implementation of above integrated measures, epidemic of major disease in 15 experimental pig farms were effectively controlled, accompanied with remarkable decrease of morbidity and morality, and significantly promotion on immunoprotective level of pig groups, reproduction performance of breeding pigs, growth performance of piglets, and other production parameters, which led to good economic and social profits.更多还原