Strengthening Regional Control of Transboundary Animal Diseases in the Greater Mekong Subregion of Southeast Asia: Four Decades of Diagnostics, Surveillance, Field Epidemiology, and Policy Translation.

Transboundary animal and emerging infectious diseases (TADs, EIDs) threaten livestock health and production, food security, and the livelihoods of smallholder farmers in Southeast Asia (SEA). Outbreaks of TADs, including foot-and-mouth disease (FMD), classical swine fever (CSF), African swine fever (ASF), and lumpy skin disease (LSD), highlight ongoing risks associated with informal animal movement and cross-border trade. We reviewed four decades of research from Thailand, Lao PDR, and Cambodia in the Greater Mekong Subregion (GMS) to track the evolution of diagnostics, surveillance, and policies for these diseases. Incremental investments in laboratory diagnostics, epidemiology, abattoir surveillance, and field health measures were integrated into disease control strategies by adaptation to resource-limited, endemic settings and shaped by regional collaboration, notably through the SEA, China and Mongolia FMD (SEACFMD) campaign. Key achievements include establishing disease prevalence baselines, improving understanding of virus dynamics, identifying local disease risk factors, identifying veterinary service gaps, and rapidly increasing diagnostic and response capacity during outbreaks. Evidence from the studies reviewed suggests that integrating diagnostics with field surveillance, socioeconomic information, and regional coordination can provide actionable insights for disease control, although implementation and effectiveness have varied between diseases, countries, and time periods. This narrative review suggests that sustainable control requires long-term adaptive development of diagnostics, surveillance, and policy translation while recognising persistent heterogeneity in veterinary capacity, surveillance coverage, and biosecurity across the region. This review is based on a narrative synthesis of published literature, institutional reports, and programme experience.