Johne’s disease is an infectious disease affecting cattle, other ruminants and non-ruminant wildlife worldwide, caused by Mycobacterium avium subspecies paratuberculosis (MAP). This review provides an up-to-date concise overview of the pathogenesis of MAP, the significance of Johne’s disease in cattle and the use of diagnostic testing at both animal and herd level in the context of seasonal pasture-based herds. While MAP can only replicate intracellularly, the bacterium is sufficiently robust to survive for months in the environment. Transmission of MAP is mostly via the faecal-oral route, however in-utero transmission in also possible. The bacteria evade the immune system by persisting in macrophages in the small intestine submucosa, with this latent stage of infection lasting, in most cases, for at least two years before bacterial shedding and clinical signs begin. The slowly progressive nature of MAP infection, poor performance of diagnostic tests and management systems that expose susceptible calves to infection make control of Johne’s disease challenging, particularly in seasonal calving herds. Testing of individual animals provides little assurance for farmers and vets due to the poor sensitivity and, in the case of ELISA, imperfect specificity of the available tests. Repeated herd-level testing is utilised by the IJCP to detect infected herds, identify high risk animals, and provide increasing confidence that test-negative herds are free of infection. The IJCP aims to control the spread of Johne’s disease in cattle in Ireland, in order to protect non-infected herds, limit the economic and animal health impact of the disease, improve calf health and reassure markets of Johne’s disease control in Ireland.

中文翻译：

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牛分枝杆菌亚种副结核感染——季节性牧场奶牛群背景下的综述

约内氏病是一种影响全世界牛、其他反刍动物和非反刍动物野生动物的传染病，由鸟分枝杆菌亚种副结核病 (MAP) 引起。这篇综述提供了关于 MAP 发病机制的最新简明概述，牛约尼氏病的重要性以及在季节性牧场牧群背景下在动物和畜群水平上使用诊断测试。虽然 MAP 只能在细胞内复制，但这种细菌足够强大，可以在环境中存活数月。MAP 的传播主要通过粪口途径传播，但也有可能在子宫内传播。细菌通过在小肠粘膜下层的巨噬细胞中持续存在来逃避免疫系统，在大多数情况下，这种感染的潜伏阶段会持续下去，在细菌脱落和临床症状开始之前至少两年。MAP 感染的缓慢进展性、诊断测试和管理系统的性能不佳会使易感犊牛受到感染，这使得约翰氏病的控制具有挑战性，特别是在季节性产犊牛群中。由于敏感性差，并且在 ELISA 的情况下，可用测试的特异性不完善，对个体动物的测试为农民和兽医提供的保证很少。IJCP 使用重复的畜群水平检测来检测受感染的畜群，识别高风险动物，并增加对检测阴性畜群没有感染的信心。IJCP 旨在控制约翰氏病在爱尔兰牛群中的传播，以保护未感染的牛群，限制该疾病对经济和动物健康的影响，