Comparative epidemiology and preparedness for African swine fever and porcine reproductive and respiratory syndrome in four major Asian swine industries

East and Southeast Asia account for over half of global pork production but face unprecedented challenges from transboundary animal diseases (TADs). African swine fever (ASF) and porcine reproductive and respiratory syndrome (PRRS) are two of the most consequential diseases reshaping the region's swine industry. This narrative review summarizes literature and institutional reports from peer-reviewed scientific databases to provide a clear comparative epidemiological overview of these diseases across a strategic cross-section of four major producers: China, Vietnam, Thailand, and the Philippines. While both viruses exploit identical regional vulnerabilities, such as high-density smallholder networks, porous border trade, and farm-level containment gaps, their transmission characteristics and evolutionary patterns differ fundamentally. Driven by extreme environmental resistance, the ASF virus operates primarily via human-mediated, anthropogenic routes and has evolved from causing acute epidemics to an unpredictable endemic state marked by recombinant and gene-deleted strains. Conversely, the highly dynamic, rapidly evolving PRRS virus acts as a self-sustaining endemic engine driven by efficient host persistence, long-distance aerosol spread, and immune-evasive genetic diversification. Furthermore, national control strategies vary widely based on production infrastructure, ranging from China's mega-industrialization and precision culling to Vietnam's reliance on partial live-attenuated vaccination, Thailand's strict physical biosecurity, and the Philippines's archipelagic zoning. Together, these approaches highlight that preparedness and disease control in each country depend on harmonized strategies, upgraded biosecurity standards, knowledge sharing among the stakeholders, and transparent surveillance aligned with the World Organization for Animal Health guidelines. Importantly, cross-learning between ASF and PRRS, as well as among other TADs' frameworks, offers a pathway to more resilient not only national but also regional food security. Ultimately, advancing transboundary preparedness in the region requires coordinated, multi-country collaboration that integrates molecular surveillance networks and validated immunization protocols with practical, system-adapted execution.