Guelbenzu-Gonzalo Maria P, Lozano Jose-Maria, O'Sullivan Padraig, Lane Elizabeth A, Graham David A
Animal Health Ireland, Carrick-On-Shannon, Ireland.
Central Veterinary Research Laboratory, Department of Agriculture, Food and the Marine, Backweston Laboratory Complex, Celbridge, Ireland.
Front Vet Sci. 2021 Aug 17;8:694774. doi: 10.3389/fvets.2021.694774. eCollection 2021.
Bovine viral diarrhoea (BVD) is an important endemic disease of cattle. In Ireland, an industry-led compulsory eradication programme began in January 2013. The main elements of this programme are the identification and elimination of persistently infected (PI) calves by testing all new-borns, the implementation of biosecurity to prevent re-introduction of disease and continuous surveillance. In 2016, a standardised framework was developed to investigate herds with positive results. This is delivered by trained private veterinary practitioners (PVP). The investigation's aims are 3-fold: firstly, to identify plausible sources of infection; secondly, to ensure that no virus-positive animals remain on farm by resolving the BVD status of all animals in the herd; and thirdly, agreeing up to three biosecurity measures with the herd owner to prevent the re-introduction of the virus. Each investigation follows a common approach comprising four steps based on information from the programme database and collected on-farm: firstly, identifying the time period when each virus-positive calf was exposed (window of susceptibility, taken as 30-120 days of gestation); secondly, determining the location of the dam of each positive calf during this period; thirdly, to investigate potential sources of exposure, either within the herd or external to it; and finally, based on the findings, the PVP and herdowner agree to implement up to three biosecurity measures to minimise the risk of reintroduction. Between 2016 and 2020, 4,105 investigations were completed. The biosecurity recommendations issued more frequently related to the risks of introduction of virus associated with contact with neighbouring cattle at pasture, personnel (including the farmer), the purchase of cattle and vaccination. Although each investigation generates farm-specific outcomes and advice, the aggregated results also provide an insight into the most commonly identified transmission pathways for these herds which inform overall programme communications on biosecurity. The most widely identified plausible sources of infection over these years included retained BVD-positive animals, Trojan births, contact at boundaries and indirect contact through herd owner and other personnel in the absence of appropriate hygiene measures. While generated in the context of BVD herd investigations, the findings also provide an insight into biosecurity practises more generally on Irish farms.
牛病毒性腹泻（BVD）是牛的一种重要地方病。在爱尔兰，一项由行业主导的强制根除计划于2013年1月启动。该计划的主要内容包括通过检测所有新生犊牛来识别和清除持续感染（PI）的犊牛、实施生物安全措施以防止疾病再次传入以及持续监测。2016年，制定了一个标准化框架来调查检测结果呈阳性的牛群。这项工作由训练有素的私人执业兽医（PVP）负责。调查的目标有三个方面：第一，确定可能的感染源；第二，通过确定牛群中所有动物的BVD状况，确保农场没有病毒阳性动物；第三，与牛群所有者商定多达三项生物安全措施，以防止病毒再次传入。每次调查都遵循一种通用方法，该方法基于程序数据库中的信息并在农场收集，包括四个步骤：第一，确定每头病毒阳性犊牛的暴露时间段（易感期，定为妊娠30 - 120天）；第二，确定在此期间每头阳性犊牛母亲的位置；第三，调查潜在的暴露源，无论是在牛群内部还是外部；最后，根据调查结果，PVP和牛群所有者商定实施多达三项生物安全措施，以尽量降低再次传入病毒的风险。2016年至2020年期间，共完成了4105次调查。发布的生物安全建议更多地涉及与牧场中邻近牛只接触、人员（包括农场主）、购买牛只和疫苗接种相关的病毒传入风险。虽然每次调查都会产生针对特定农场的结果和建议，但汇总结果也能让我们深入了解这些牛群最常见的传播途径，为生物安全方面的整体计划沟通提供参考。这些年来最广泛确定的可能感染源包括留存的BVD阳性动物、特洛伊出生、边界接触以及在缺乏适当卫生措施的情况下通过牛群所有者和其他人员的间接接触。虽然这些结果是在BVD牛群调查的背景下得出的，但这些发现也能让我们更全面地了解爱尔兰农场的生物安全做法。
