A UK platform for the control of Bovine Viral Diarrhoea:Application of a novel disease simulation model to guide programme development & policy design

牛的地方病对全世界牛的福利产生重大负面影响，降低了农场生产力、盈利能力和可持续性。地方病除非得到积极控制，否则在人群中持续存在。在英国，地方病的控制方案往往集中于相对较少的关键条件，如乳腺炎、牛病毒性腹泻（BVD）或约翰氏病，并由个体农场、兽医或小型利益相关者团体实施。最近，联合王国的地方病控制被下放，BVD是地方病控制由四个下放的国家各自独立处理的一个例子。然而，除了布鲁氏菌病，没有一个英国国家正式根除任何地方性疾病。为了在地方病控制和根除方面实现逐步改变，需要采取国家和多国协调的疾病控制方法，这项研究的目的是创造一种新的解决方案，指导英国国家BVD控制方案。我们的解决方案是开发一种传染病模拟建模框架，适用于英国养牛业的所有部门和英国所有国家，能够同时模拟农场内的牛群、农场之间的运动和地理关系、不同的国家BVD控制计划，并纳入不同利益相关者（农民、兽医、兽医、兽医）的行为。和项目机构)和农业系统，横跨英国所有四个国家的整个网络。采用这种协作方法将确保所开发的疾病模型具有相关性、实用性并能满足每个国家的需求。将开发模拟模型来模拟每只动物的状态，包括免疫状态（易感、暴露/免疫）和感染状态的特征。我们将把这个模型与现有的整个养牛场的模拟模型结合起来，该模型与一个整体环境生命周期分析模型REMEDY相关联。现有的测试数据库将用于定义英国BVD的空间和时间模式，以及在模拟模型中用于表示BVD的关键流行病学和空间参数。为了建立农场间传播的模型，我们将使用机器学习方法，基于牛群人口统计、空间和运动数据，为英国养牛场创建一个新的分类系统。这将允许更详细地反映英国农业人口的多样性，并使用新定义的分类系统来模拟跨英国农场网络的牛贸易。农场内传染病模型和网络模拟模型将与测试数据的分析相结合，创建英国范围内的BVD国家传染病模拟模型。将使用与利益相关者的共同设计过程来定义当前的BVD控制方案和未来感兴趣的替代方案，并定义与BVD控制相关的目标和行为。将模拟由利益相关者定义的情景，并评估结果的多个方面，包括流行病学、经济和环境因素。结果将提交给利益攸关方，并根据模型产生信息丰富和有影响力的产出的能力对模型进行评估，这些产出能够影响利益攸关方的行为并影响未来的地方病根除方案。这项研究将影响英国地方病控制的一系列关键利益相关者，包括动物、兽医、农民、政府，通过提供关于不同疾病控制方案的绩效和每个下放国家方案之间相互作用的重要信息，从而允许关于控制方案和政策制定的知情讨论。这一模式的遗产将不仅是一个支持BVD根除的模式，而且是一个易于推广的框架，用于模拟牛的其他地方病的控制。

Endemic disease in cattle has a substantial negative impact on welfare of cattle worldwide, reduces farm productivity and profitability and sustainability. Endemic diseases persist within populations unless actively controlled. Control programmes for endemic disease in the UK have tended to focused on relatively few key conditions such as Mastitis, Bovine Viral Diarrhoea (BVD) or Johnes Disease, and implemented by individual farms, vets, or small stakeholder groups. Recently the control of endemic disease within the UK was devolved, and BVD is an example where endemic disease control is handled independently by each of the four devolved nations. However, except for brucellosis, no UK nation has officially eradicated any endemic disease. To achieve a step change in endemic disease control and eradication, national and multi-national, coordinated approaches to disease control are required and the aim of this research is to create a novel solution to guide UK national control programmes for BVD. Our solution is to develop an infectious disease simulation modelling framework applicable to all sectors across the UK cattle industry and across all nations within the UK that is capable of simultaneously modelling both cattle populations within farms, the movements and geographical relationships between farms, the different national BVD control programmes and incorporate the behaviours of different stakeholders (farmers, vets, and programme bodies) and farming systems across the entire network from all four UK nations. Use this collaborative approach will ensure development of a disease model is relevant, practical and addresses the needs of each individual country. The simulation model will be developed to model the status of each animal, including characteristics of immune status (susceptible, exposed/immune) and infection status. We will incorporate this model with an existing simulation model of a whole cattle farm linked to a holistic environmental life-cycle analysis model, REMEDY. Existing test databases will be used to define UK spatial and temporal patterns of BVD and the key epidemiological and spatial parameters to use within the simulation model to represent BVD. To establish a model of between farm spread we will use machine learning methods to create a new classification system for UK cattle farms, based on the herd demographics, spatial and movement data. This will allow a more detailed reflection of the diversity within the UK's farming population and use the newly defined classification system to simulate the trade if cattle across the networks of UK farms. The within-farm infectious disease model and the network simulation models will be combined with the analysis of the test data to create a UK wide national infectious disease simulation model of BVD. A co-design process with stakeholders will be used define current BVD control programmes and future alternative scenarios of interest and define their goals and behaviours relevant to BVD control. The scenarios defined by the stakeholders will be simulated and multiple aspects of the outcomes evaluated, including epidemiological, economic, and environmental components. The results will be presented to stakeholders and the model evaluated on the model's ability to produce informative and impactful outputs capable of influencing stakeholder behaviour and shape future endemic disease eradication programmes. This research will impact a range of key stakeholders within UK endemic disease control, including animals, vets, farmers, government, by providing vital information on the performance of different disease control scenarios ant the interactions between each of the devolved nations programmes, thus allowing for informed discussions regarding control programme and policy development. The legacy of this model will not only be a model to support BVD eradication but also, a readily generalisable framework for modelling the control of other endemic disease of cattle.