Gurung Ratna B, Begg Douglas J, Whittington Richard J
Department of Livestock, National Centre for Animal Health, Thimphu, Bhutan.
Sydney School of Veterinary Science and School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Camden, New South Wales, Australia.
Vet Med Sci. 2018 Nov;4(4):288-295. doi: 10.1002/vms3.114. Epub 2018 Jul 5.
Johne's disease is an economically important ruminant disease predominantly affecting cattle, sheep and goats. The economic losses are due to early culling, reduced growth rate, progressive weight loss and reduced production. It is caused by Mycobacterium avium subspecies paratuberculosis (MAP). Johne's disease was reported in cattle in Bhutan, based on clinical signs and histopathology; in the late 1990s samples from one mithun that was suspected to have died due to this disease was confirmed by molecular testing at the Faculty of Veterinary Science, University of Sydney, Australia. However, no detailed study on prevalence of JD has been attempted in Bhutan. Objective of this study was to conduct serosurveillance to determine the national prevalence of Johne's disease in cattle for the period 2013-2014 to provide the basis for planning a future control strategy. A national serosurvey was conducted wherein a two-stage sampling procedure was used with 95% confidence and an error level of ±0.05. The sample size required for the survey was calculated using the software-Survey Toolbox for Livestock Diseases, available as Epitools at http://www.ausvet.com.au. A total of 1123 serum samples were collected from an administrative structure of 52 villages, 40 sub-districts and 15 districts. Serum samples were tested using commercially available antibody enzyme linked immunosorbent assay. Statistical analysis was performed using GraphPad Prism 5.0. Illustration such as maps was produced using QGIS version 2.18 'Las Palmas. The mean national apparent prevalence of Johne's disease was found to be 2.31 (26/1123) (95% CI: 0.80-4.50) with an estimated true prevalence was found to be 8.00 (95% CI: 2.00-17.00). Trongsa district had the highest prevalence (12.96) followed by Zhemgang (4.34), Lhuntse (4.25), Sarpang (3.89), Bumthang (3.60), Trashigang (2.67) and Haa (2.63). Prevalence for all other districts was 2.00 or below. Seropositive samples were reported from all over the country with varying levels of sero-positivity. In the recent past many more cattle were imported from India to boost dairy production. Nevertheless, the wide distribution of seroreactive JD cattle all over the country is a concern for future control. Therefore, in future, a detailed study on the impact of cattle import with regard to disease incursion such as Johne's disease and other diseases should be undertaken.
副结核是一种对经济有重要影响的反刍动物疾病，主要感染牛、绵羊和山羊。经济损失源于过早淘汰、生长速度降低、体重逐渐减轻以及产量下降。它由副结核分枝杆菌鸟型亚种（MAP）引起。根据临床症状和组织病理学，不丹曾报告牛感染了副结核；20世纪90年代末，一只疑似死于该病的米什米牛的样本在澳大利亚悉尼大学兽医学院通过分子检测得到证实。然而，不丹尚未对副结核的流行情况进行详细研究。本研究的目的是进行血清学监测，以确定2013 - 2014年期间不丹全国牛群中副结核的流行情况，为规划未来的控制策略提供依据。开展了一项全国血清学调查，采用两阶段抽样程序，置信度为95%，误差水平为±0.05。使用软件“家畜疾病调查工具箱”（可在http://www.ausvet.com.au以Epitools获取）计算调查所需的样本量。从52个村庄、40个分区和15个地区的行政结构中总共收集了1123份血清样本。血清样本使用市售的抗体酶联免疫吸附测定法进行检测。使用GraphPad Prism 5.0进行统计分析。使用QGIS 2.1版“拉斯帕尔马斯”制作地图等图表。发现全国副结核的平均表观流行率为2.31（26/1123）（95%置信区间：0.80 - 4.50），估计真实流行率为8.00（95%置信区间：2.00 - 17.00）。通萨地区的流行率最高（12.96），其次是扎西岗（4.34）、伦杰（4.25）、萨庞（3.89）、布姆唐（3.60）、特拉希冈（2.67）和哈阿（2.63）。所有其他地区的流行率为2.00或更低。全国各地均报告了血清阳性样本，血清阳性水平各不相同。最近，为提高乳制品产量从不丹进口了更多的牛。尽管如此，血清反应阳性的副结核牛在全国广泛分布，这对未来的控制构成了担忧。因此，未来应就牛进口对诸如副结核等疾病传入的影响开展详细研究。
