Preventing contagious ovine digital dermatitis: Characterisation of bacterial pathogens and development of disease control measures to prevent transmi

绵羊接触性皮炎(Codd)是导致绵羊跛行的严重原因。它影响了大约一半的英国羊群，并在全球范围内出现。由于其严重性，鳕鱼对绵羊的福利有重大和非常明显的影响。与疾病控制相关的经济后果以及抗生素的高水平使用，对可持续性产生了负面影响。在2021年反刍动物健康与福利组织对英国畜牧业农民的调查中，Codd是畜牧业最优先考虑的地方病；而最近的调查发现，提高对疾病传播和预防方法的了解是农民和兽医Codd研究的首要任务。这项研究的目的是告知和设计生物安全协议，以防止Codd在农场之间和农场内的传播。目的1：比较、鉴定和定位现场狐狸和鳕鱼的病原菌群。实验研究的证据表明，Codd的发生是由于先前存在的足部病变重叠感染了三种密螺旋体细菌：中密螺旋体、噬菌密螺旋体和足密螺旋体(DD密螺旋体)。要为农场的疾病预防提供信息，这需要进行实地验证。因此，我们将利用16个S的元基因组分析和定量聚合酶链式反应来比较这些来自鳕鱼和狐狸的现场病例中的DD密螺旋体的微生物群、存在、丰度和毒力特征。目的：对牛、羊数字皮炎皮损分离的中、噬、足三种弓形虫进行全基因组测序。长期以来，人们一直关注的是由牛数字皮炎(BDD)引起的DD密螺旋体，以及物种间的传播。这有可能将疾病传播到幼稚的农场，并可能成为受地方性影响的农场的感染源。我们将使用来自受BDD和Codd影响的农场的中型T.dium、T.phagedenis和T.pedis分离株的全基因组分型来研究这一假设。我们还将调查它们的细菌多样性和毒力因素。目的：评价消除绵羊足部Codd病原体的消毒方案。随着Codd的继续传播，目前的生物安全建议显然是不够的。我们将进行农场随机对照试验，以调查消毒方案对消除羊脚中Codd病原体的效果。这些方案将基于从目前的研究和试点体内和体外疗效数据收集的证据。临床检查、细菌培养和定量聚合酶链式反应(QPCR)将用于疗效评估。

Contagious ovine digital dermatitis (CODD) is a severe cause of sheep lameness. It affects approximately half of UK sheep flocks, and is emerging globally. Due to its' severity, CODD has a substantial and highly visible impact on sheep welfare. The economic consequences, and high levels of antibiotic use associated with disease control, negatively affect sustainability. In the 2021 Ruminant Health and Welfare Group survey of UK livestock farmers, CODD was a top priority endemic disease for the livestock industry; whilst recent surveys identified that improved understanding of disease transmission and prevention methods were farmers and vets top CODD research priorities. The aim of this study is to inform and devise biosecurity protocols for prevention of between and within farm transmission of CODD. Objective 1: Comparison, characterisation and localisation of pathogenic bacterial populations from field cases of footrot and CODD. Evidence from experimental studies demonstrated that CODD occurs as a result of superinfection of pre-existing footrot lesions with three treponeme bacteria; Treponema medium, Treponema phagedenis and Treponema pedis (DD treponemes). To inform disease prevention on farms, this requires field validation. Therefore, we will compare the microbiomes, the presence, abundance and virulence characteristics of these DD treponeme bacteria from field cases of CODD and footrot using 16 S metagenomic analysis and quantitative PCR. Pathogen load and localisation will be studied using fluorescence in situ hybridisation.Objective 2: Whole genome sequencing of T.medium, T.phagedenis, T.pedis isolates from cattle and sheep digital dermatitis lesions.It is a long-held concern that the DD treponemes originated from bovine digital dermatitis (BDD), and that transmission between species occurs through the farm environment. This risks introduction of disease to naïve farms and maybe a source of infection in endemically affected farms. We will investigate this hypothesis using whole genome typing of T.medium, T.phagedenis and T.pedis isolates from farms affected by both BDD and CODD. We will also investigate their bacterial diversity and virulence factors. Objective 3: Evaluate disinfection protocols for the elimination of CODD pathogens from sheep's feet. As CODD continues to spread it is evident that current biosecurity advice is inadequate. We will conduct farm RCT trials to investigate the efficacy of disinfection protocols for the elimination of the CODD pathogens from sheep's feet. The protocols will be based on evidence gathered from the current study and pilot in vivo and in vitro efficacy data. Clinical examination, bacterial culture and qPCR will be used to assess efficacy.