经典瘙痒病是小反刍动物的朊病毒病,其传染性病原体已被证明在环境中极其持久。目前,许多政府兽医顾问建议在瘙痒病爆发后进行清洁和消毒(C&D),并在大多数受影响的农场实施。然而,这些程序的有效性尚不清楚。这项研究的目的是回顾有关经典瘙痒病暴发后农场C&D协议的现有文献和指南,并评估其有效性以及政策和立法要求翻译在实际水平上所面临的挑战。对文献进行了回顾,以确定在瘙痒病爆发后使用的农场C&D方案,评估那些对农场上的瘙痒病制剂的持久性具有高风险的材料,并审查推荐的C&D方案有效性的现有证据。在英国(GB)还组织了一次专家研讨会,以评估:在GB农场实施C&D协议时使用的决策过程,专家们对这些协议的有效性和需要的变化的看法,以及他们对政策和研究的潜在建议的看法。文献综述的结果表明,目前推荐的C&D方案[用含有20,000ppm游离氯或2M氢氧化钠(NaOH)的次氯酸钠处理1小时]是基于实验室实验。只进行了四次田间农场实验,这表明,由于在重新放养后再次出现瘙痒病感染,缺乏关于农场C&D方案有效性的数据。与室外环境控制有关的建议,实施起来既困难又昂贵,国家之间不同。专家研讨会的结论是,目前要考虑的具有成本效益的C&D替代品,因此,基于C&D的控制只能结合额外的时间限制,重新放养和更换非易感牲畜或更具遗传抗性的牲畜,可用的地方。与会者一致认为,受瘙痒病影响的农场仍应完成C&D,因为它被认为是“良好的疾病实践”,并且可能降低朊病毒蛋白的水平。与会者认为,由于农场类型的重大变化,制定的任何附加协议都不应“过于规范”(不应在具体政策中写下),农场设备和装置。在这种情况下,对农场的经典瘙痒病的控制应设计为具有一定的C&D水平,并结合临时禁止重新放养和用敏感性有限的牲畜代替。
Classical scrapie is a
prion disease of small ruminants, the infectious agent of which has been shown to be extremely persistent in the environment. Cleaning and disinfection (C&D) after a scrapie outbreak is currently recommended by many governments\' veterinary advisors and implemented in most farms affected. Yet, the effectiveness of these procedures remains unclear. The aim of this study was to review existing literature and
guidelines regarding farm C&D protocols following classical scrapie outbreaks and assess their effectiveness and the challenges that translation of policy and legislative requirements present at a practical level. A review of the literature was conducted to identify the on-farm C&D protocols used following outbreaks of scrapie, assess those materials with high risk for persistence of the scrapie agent on farms, and review the existing evidence of the effectiveness of recommended C&D protocols. An expert workshop was also organised in Great Britain (GB) to assess: the decision-making process used when implementing C&D protocols on GB farms, the experts\' perceptions on the effectiveness of these protocols and changes needed, and their views on potential recommendations for policy and research. Outputs of the literature review revealed that the current recommended protocol for C&D [1 h treatment with sodium hypochlorite containing 20,000 ppm free chlorine or 2 M sodium hydroxide (NaOH)] is based on laboratory experiments. Only four field farm experiments have been conducted, indicating a lack of data on effectiveness of C&D protocols on farms by the re-occurrence of scrapie infection post re-stocking. Recommendations related to the control of outdoor environment, which are difficult and expensive to implement, vary between countries. The expert workshop concluded that there are no practical, cost-effective C&D alternatives to be considered at this time, with control therefore based on C&D only in combination with additional time restrictions on re-stocking and replacement with non-susceptible livestock or more genetically resistant types, where available. Participants agreed that C&D should still be completed on scrapie affected farms, as it is considered to be \"good disease practice\" and likely to reduce the levels of the
prion protein. Participants felt that any additional protocols developed should not be \"too prescriptive\" (should not be written down in specific policies) because of significant variation in farm types, farm equipment and installations. Under this scenario, control of classical scrapie on farms should be designed with a level of C&D in combination with re-stocking temporal ban and replacement with livestock of limited susceptibility.