Animal Health Service (GD), Deventer, The Netherlands.
Vet Microbiol. 2010 May 19;142(3-4):217-24. doi: 10.1016/j.vetmic.2009.10.003. Epub 2009 Oct 20.
This study was set up to get more insights in the severity and relevance of porcine circovirus type 2 (PCV2) infections in Dutch fattening farms in an endemic PCV2-situation with no clinical signs of post-weaning multisystemic wasting syndrome (PMWS). In part A of the study, in total 29 commercial fattening farms with varying percentages of pneumonia and pleurisy at slaughter were examined. Blood samples were collected at random by cross-sectional sampling; 10 in the age of 10-12 weeks, 10 at the age of 16 weeks and 10 blood samples at the end of the finishing period (20-22 weeks of age). Serum samples were examined for the presence of PCV2 IgM and IgG antibodies and for antibodies against other porcine lung pathogens. In part B, 8 "high" and 8 "low" herds were selected. The 8 "high" herds were defined as herds having high percentages of lung lesions (pneumonia) at slaughter, and the 8 "low" herds had low percentages of pneumonia at slaughter. For both the "high" and "low" herds, 3 pigs showing signs of respiratory distress were selected for necropsy (n=48). Lung tissue samples were examined post-mortem for macroscopic and histopathological lesions, and for the presence of bacteria and viruses. The results of part A showed that, pigs at 16 weeks of age with IgM antibodies against PCV2 had a lower probability of having pleuritis at slaughter (OR 0.34, P<0.000). Pigs in the age category of 20-22 weeks, and with IgM antibodies against PCV2, also had a lower probability of having pneumonia at slaughter (OR 0.29, P=0.032). In part B lobus apicalis pneumonia, PCV2 in macroscopically unaffected lungs, Pasteurella multocida, Mycoplasma hyopneumoniae, and swine influenza viruses were all found significantly more often in "high" than in "low" pigs at autopsy. High PCV2 DNA loads (>10(4) PCV2 DNA copies/mg) were found in lungs of 14 (58%) "high", and in 7 (29%) of the "low" pigs (P=0.13). In 11 of the 19 affected lungs from "high" pigs, high PCV2 DNA loads were found in combination with one or more other lung pathogens, while this was found only in 5 of the 17 affected lungs from "low" pigs (P=0.02). This study confirms the hypothesis that PCV2 plays a role in pneumonia and pleurisy in 10-24 weeks old fattening pigs, not only in herds with a high prevalence of PMWS, but also in herds with no clinical signs of PMWS.
本研究旨在深入了解在荷兰育肥场中，在无断奶后多系统衰弱综合征（PMWS）临床症状的地方性猪圆环病毒 2 型（PCV2）感染的严重程度和相关性。在研究的 A 部分中，共检查了 29 家具有不同屠宰肺炎和胸膜炎百分比的商业育肥场。通过横断面抽样随机采集血液样本；10 份在 10-12 周龄时采集，10 份在 16 周龄时采集，10 份在育肥末期（20-22 周龄）采集。检查血清样本中是否存在 PCV2 IgM 和 IgG 抗体以及其他猪肺部病原体的抗体。在 B 部分中，选择了 8 个“高”和 8 个“低”畜群。8 个“高”畜群定义为屠宰时肺部病变（肺炎）百分比高的畜群，而 8 个“低”畜群的屠宰时肺炎百分比低。对于“高”和“低”畜群，均选择 3 头有呼吸窘迫迹象的猪进行剖检（n=48）。对肺组织样本进行尸检，检查宏观和组织病理学病变，并检查细菌和病毒的存在。A 部分的结果表明，16 周龄时具有针对 PCV2 的 IgM 抗体的猪在屠宰时患有胸膜炎的可能性较低（OR 0.34，P<0.000）。20-22 周龄的猪，以及具有针对 PCV2 的 IgM 抗体，在屠宰时也患有肺炎的可能性较低（OR 0.29，P=0.032）。在 B 部分中，尖叶肺炎、肉眼未见病变的肺中的 PCV2、多杀性巴氏杆菌、猪肺炎支原体和猪流感病毒在剖检时均在“高”猪中比在“低”猪中更为常见。在 19 头“高”猪的 14 头（58%）肺中发现了高载量的 PCV2 DNA（>10（4）PCV2 DNA 拷贝/mg），而在 7 头（29%）“低”猪中发现了高载量的 PCV2 DNA（P=0.13）。在 19 头“高”猪中 11 头受影响的肺中，高载量的 PCV2 DNA 与一种或多种其他肺部病原体同时存在，而在 17 头“低”猪中仅在 5 头受影响的肺中发现（P=0.02）。本研究证实了这样一个假设，即在 10-24 周龄育肥猪中，PCV2 不仅在 PMWS 高流行畜群中，而且在无 PMWS 临床症状的畜群中，也在肺炎和胸膜炎中起作用。
