Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.
Lamphun Provincial Livestock Office, Lamphun, Thailand.
BMC Vet Res. 2020 Jun 1;16(1):170. doi: 10.1186/s12917-020-02392-6.
Foot and mouth disease (FMD) is a highly infectious and contagious febrile vesicular disease of cloven-hoofed livestock with high socio-economic consequences globally. In Thailand, FMD is endemic with 183 and 262 outbreaks occurring in the years 2015 and 2016, respectively. In this study, we aimed to assess the spatiotemporal distribution of FMD outbreaks among cattle in Chiang Mai and Lamphun provinces in the northern part of Thailand during the period of 2015-2016. A retrospective space-time scan statistic including a space-time permutation (STP) and the Poisson and Bernoulli models were applied in order to detect areas of high incidence of FMD.
Results have shown that 9 and 8 clusters were identified by the STP model in 2015 and 2016, respectively, whereas 1 and 3 clusters were identified by the Poisson model, and 3 and 4 clusters were detected when the Bernoulli model was applied for the same time period. In 2015, the most likely clusters were observed in Chiang Mai and these had a minimum radius of 1.49 km and a maximum radius of 20 km. Outbreaks were clustered in the period between the months of May and October of 2015. The most likely clusters in 2016 were observed in central Lamphun based on the STP model and in the eastern area of Chiang Mai by the Poisson and Bernoulli models. The cluster size of the STP model (8.51 km) was smaller than those of the Poisson and Bernoulli models (> 20 km). The cluster periods in 2016 were approximately 7 months, while 4 months and 1 month were identified by the Poisson, Bernoulli and STP models respectively.
The application of three models provided more information for FMD outbreak epidemiology. The findings from this study suggest the use of three different space-time scan models for the investigation process of outbreaks along with the follow-up process to identify FMD outbreak clusters. Therefore, active prevention and control strategies should be implemented in the areas that are most susceptible to FMD outbreaks.
口蹄疫（FMD）是一种高度传染性和接触传染性的偶蹄动物发热性水疱病，在全球范围内具有很高的社会经济影响。在泰国，口蹄疫流行，分别于 2015 年和 2016 年发生了 183 次和 262 次疫情爆发。在这项研究中，我们旨在评估 2015-2016 年期间泰国北部清迈府和南奔府牛群中口蹄疫爆发的时空分布。应用回顾性时空扫描统计，包括时空置换（STP）和泊松模型和伯努利模型，以检测口蹄疫高发地区。
结果表明，STP 模型在 2015 年和 2016 年分别识别出 9 个和 8 个集群，泊松模型识别出 1 个集群，伯努利模型识别出 3 个集群。在 2015 年，观察到清迈最有可能的集群，这些集群的最小半径为 1.49km，最大半径为 20km。疫情爆发于 2015 年 5 月至 10 月期间呈聚集性。基于 STP 模型，2016 年最有可能的集群出现在南奔中部，泊松模型和伯努利模型则出现在清迈东部。STP 模型的集群规模（8.51km）小于泊松模型和伯努利模型（>20km）。2016 年的集群期约为 7 个月，泊松模型、伯努利模型和 STP 模型分别确定了 4 个月和 1 个月的集群期。
三种模型的应用为口蹄疫爆发的流行病学提供了更多信息。本研究结果表明，在疫情调查过程和后续监测过程中，应使用三种不同的时空扫描模型来识别口蹄疫爆发集群。因此，应在最易发生口蹄疫爆发的地区采取积极的预防和控制策略。
