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

羊传染性趾皮炎（CODD）是引起绵羊跛行的一种严重原因。它影响了大约一半的英国羊群，并正在全球范围内出现。由于其严重性，CODD对羊的福利有重大和高度明显的影响。经济后果以及与疾病控制相关的大量抗生素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是畜牧业的首要地方病;而最近的调查发现，提高对疾病传播和预防方法的理解是农民和兽医的首要CODD研究重点。本研究的目的是告知和制定生物安全协议，以防止农场内和农场之间的传播。目的1：比较、表征和定位来自腐蹄病和CODD的现场病例的病原菌群。来自实验研究的证据表明，CODD的发生是由于预先存在的足病变与三种密螺旋体细菌的重叠感染;密螺旋体介质，吞噬密螺旋体和足密螺旋体（DD密螺旋体）。为了告知农场的疾病预防，这需要现场验证。因此，我们将使用16 S宏基因组分析和定量PCR比较来自CODD和腐蹄病的现场病例的这些DD密螺旋体细菌的微生物组、存在、丰度和毒力特征。病原体负荷和定位将使用荧光原位杂交研究。目的2：全基因组测序的T.medium，T.phagedenis，T.pedis分离的牛和羊趾皮炎lesions.It是一个长期关注的DD密螺旋体起源于牛趾皮炎（BDD），并通过农场环境发生物种之间的传播。这有可能将疾病引入未经处理的农场，并可能成为地方性感染农场的感染源。我们将使用来自受BDD和CODD影响的农场的培养基毛癣菌、噬菌毛癣菌和足毛癣菌分离株的全基因组分型来研究这一假设。我们还将研究它们的细菌多样性和毒力因子。目的3：评价从羊脚中消除CODD病原体的消毒方案。随着慢性阻塞性肺病的继续蔓延，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上的CODD病原体的有效性。方案将基于从当前研究和初步体内和体外疗效数据中收集的证据。临床检查、细菌培养和qPCR将用于评估疗效。

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.