Foot and mouth disease (FMD) is recognized as an endemic disease in Thailand and throughout other countries in Southeast Asia. The underreporting of FMD outbreaks has affected the true status of the disease. This study aimed to determine the number of dairy farms in Chiang Mai that had experienced FMD outbreaks (FMD outbreak farm) during 2015–2016 using capture-recapture (CR) methods. Two independent FMD outbreak data sources including data from the livestock authorities and survey questionnaires were analyzed using Chapman estimator and Chao estimator. Results showed that the estimated number of FMD outbreak farms was 264 (95% CI = 250, 277) and 273 (95% CI = 259, 292) farms based on the Chapman estimator and Chao estimator, respectively. The estimated prevalence of FMD corresponding to the Chapman estimator was lower than the Chao estimator. The active approach of the survey method offered a higher degree of sensitivity compared to the passive method used by the livestock authorities. Estimations from the CR method provided an upper bound for the true number of outbreak farms. This study demonstrated the use of the CR method to estimate the true status of FMD outbreaks. Our proposed approach can potentially be used as a tool to enhance the accuracy and sensitivity of established monitoring and surveillance systems.

口蹄疫（FMD）在泰国和整个东南亚其他国家被认为是地方病。口蹄疫暴发的报道不足影响了该病的真实状况。这项研究旨在通过捕获-捕获（CR）方法确定2015-2016年清迈经历FMD爆发的奶牛场（FMD爆发场）的数量。使用查普曼（Chapman）估计量和超（Chao）估计量分析了两个独立的口蹄疫暴发数据源，包括来自畜牧当局的数据和调查问卷。结果表明，基于查普曼估计量和昭估计量，FMD爆发农场的估计数量分别为264个（95％CI = 250、277）和273个（95％CI = 259、292）。对应于Chapman估计量的FMD估计患病率低于Chao估计量。与牲畜当局使用的被动方法相比，调查方法的主动方法提供了更高的敏感性。CR方法的估计为实际爆发农场的数量提供了上限。这项研究证明了使用CR方法来估计口蹄疫暴发的真实状况。我们提出的方法可以潜在地用作提高已建立的监视和监视系统的准确性和敏感性的工具。