Tobias T J, Klinkenberg D, Bouma A, van den Broek J, Daemen A J J M, Wagenaar J A, Stegeman J A
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
Prev Vet Med. 2014 Jun 1;114(3-4):223-30. doi: 10.1016/j.prevetmed.2014.02.008. Epub 2014 Mar 1.
Actinobacillus pleuropneumoniae causes respiratory disease in pigs and despite the use of preventive measures such as vaccination and antimicrobials clinical outbreaks still occur. At weaning often many piglets are not colonised. If differences in prevalence between litters are large and if factors were known that could explain these differences, this may provide an opportunity to raise groups of A. pleuropneumoniae free piglets. To this end, a cohort study was performed on two endemically infected farrow-to-finish farms. Seventy-six of 133 sows were selected using stratified random selection by parity. Farmers complied with a strict hygiene and animal management protocol to prevent transmission between litters. Tonsil brush and serum samples taken three weeks before parturition were tested for antigen with an apxIVA qPCR and antibodies with Apx and Omp ELISAs, respectively. Three days before weaning tonsil brush samples from all piglets (n=871) were collected and tested for antigen. Whereas all sows tested positive both in serology tests as well as qPCR, 0.41 of the litters tested fully negative and 0.73 of all piglets tested negative. The proportion of positively tested piglets in positive litters ranged from 0.08-1.0 (median=0.36). A grouped logistic regression model with a beta binomial distribution of the probability for piglets to become infected was fitted to the data and associations with explanatory variables were explored. To test the possibility that alternatively the clustering was caused by onwards transmission among the piglets, a transmission model was fitted to the data incorporating sow-piglet and piglet-piglet transmission, but this model did not fit better. The results of this study showed that the number of colonised suckling piglets was highly clustered and mainly attributable to the variability of infectiousness of the dam, but no dam related risk factor for colonisation status of litter or piglets within litters could be identified.
胸膜肺炎放线杆菌可导致猪的呼吸道疾病，尽管采取了疫苗接种和使用抗菌药物等预防措施，但临床疫情仍时有发生。在断奶时，许多仔猪往往未被该菌定植。如果窝与窝之间的流行率差异很大，并且已知能够解释这些差异的因素，那么这可能为培育无胸膜肺炎放线杆菌仔猪群提供机会。为此，在两个地方流行感染的从产仔到育肥农场进行了一项队列研究。通过按胎次分层随机抽样，从133头母猪中选出了76头。养殖户遵守严格的卫生和动物管理方案，以防止窝与窝之间的传播。在分娩前三周采集的扁桃体刷检样本和血清样本，分别用apxIVA定量聚合酶链反应检测抗原，并用Apx和Omp酶联免疫吸附测定法检测抗体。在断奶前三天，采集所有仔猪（n = 871）的扁桃体刷检样本并检测抗原。虽然所有母猪在血清学检测和定量聚合酶链反应中均呈阳性，但0.41的窝检测完全为阴性，所有仔猪中有0.73检测为阴性。阳性窝中检测呈阳性的仔猪比例在0.08 - 1.0之间（中位数 = 0.36）。将具有仔猪感染概率的β二项分布的分组逻辑回归模型应用于数据，并探索与解释变量的关联。为了检验仔猪之间的聚集性是否可能是由仔猪间的传播引起的，将一个包含母猪 - 仔猪和仔猪 - 仔猪传播的传播模型应用于数据，但该模型拟合效果不佳。本研究结果表明，已定植的哺乳仔猪数量高度聚集，主要归因于母猪传染性的变异性，但未发现与窝或窝内仔猪定植状态相关的母猪风险因素。
