Letho Sangay, Compton Chris
Regional Livestock Development Centre, Department of Livestock, Khangma, Trashigang, Bhutan.
EpiCentre, School of Veterinary Science, Massey University, Palmerston North, New Zealand.
BMC Vet Res. 2025 Aug 19;21(1):519. doi: 10.1186/s12917-025-04815-8.
Foot and Mouth Disease (FMD) is an important disease in livestock in Bhutan due to its significant social and economic impacts to the farmers as well as to the government. FMD outbreaks continue to occur every year with greater frequency in some parts of the country despite the implementation of control measures. It is imperative to understand the current patterns of the disease for planning effective control programs. Therefore, this study aimed to investigate the spatial and temporal patterns of FMD in Bhutan since the most recent national survey.
Nine year's (2011-2019) of national FMD outbreak data was used for this study. An investigation of global spatial autocorrelation was undertaken using the K difference function statistic and local spatial clusters of FMD outbreaks using Kulldorff's spatial scan statistic. Retrospective spatio-temporal analysis was conducted using a Bernoulli probability model with monthly aggregation of data. A non-stationary cosinor model was used to examine seasonality and trend of outbreaks.
The K function statistic detected significant global spatial autocorrelation of FMD outbreaks (p < 0.02) and Kulldorff's spatial scan statistic identified two outbreak clusters in west Bhutan- the first primary cluster (p < 0.002) with relative risk (RR) of 5.22 and radius of 19.77 km in Paro and Thimphu districts and the second primary cluster (p < 0.006, RR = 8.44 radius: 8.98 km) in Punakha and Wangdue Phodrang districts. The spatio-temporal scan test detected a single significant (P < 0.001) space-time cluster of 22 FMD outbreaks centred in south-west Bhutan with a radius of 60 km over an 8-month period in 2018-2019. The temporal analysis indicated that, on an average there were 0.5 (95% CI: 0.2-0.8) additional outbreaks per month in the seasonal winter peaks at 1.9 months (95% CI: 12.55 -3.64) compared with the overall monthly average.
The western and southern regions of Bhutan have experienced the greatest overall incidence and significant spatial and spatio-temporal clusters of outbreaks of FMD during the period 2011-2019, These findings in districts in the western medium FMD risk surveillance zone threaten progress to control of FMD in Bhutan.
口蹄疫（FMD）在不丹是家畜的一种重要疾病，因为它对农民以及政府都有重大的社会和经济影响。尽管实施了控制措施，但口蹄疫疫情每年仍在该国某些地区更频繁地发生。了解该疾病的当前模式对于规划有效的控制计划至关重要。因此，本研究旨在调查自最近一次全国调查以来不丹口蹄疫的空间和时间模式。
本研究使用了九年（2011 - 2019年）的全国口蹄疫疫情数据。使用K差异函数统计量进行全局空间自相关调查，并使用Kulldorff空间扫描统计量对口蹄疫疫情的局部空间聚类进行调查。使用具有每月数据汇总的伯努利概率模型进行回顾性时空分析。使用非平稳余弦模型检查疫情的季节性和趋势。
K函数统计量检测到口蹄疫疫情存在显著的全局空间自相关（p < 0.02），Kulldorff空间扫描统计量在不丹西部识别出两个疫情聚类——第一个主要聚类（p < 0.002），相对风险（RR）为5.22，半径为19.77公里，位于帕罗和廷布地区；第二个主要聚类（p < 0.006，RR = 8.44，半径：8.98公里）位于普纳卡和旺杜波德朗地区。时空扫描测试检测到一个显著（P < 0.001）的时空聚类，在2018 - 2019年的8个月期间，以不丹西南部为中心，有22起口蹄疫疫情，半径为60公里。时间分析表明，与总体月平均水平相比，在季节性冬季高峰（1.9个月，95%可信区间：12.55 - 3.64），每月平均额外爆发0.5起（95%可信区间：0.2 - 0.8）疫情。
在2011 - 2019年期间，不丹的西部和南部地区总体发病率最高，且口蹄疫疫情存在显著的空间和时空聚类。西部中等口蹄疫风险监测区各地区的这些发现威胁到不丹口蹄疫控制工作的进展。
