Challenges and responses of malaria elimination in a high-endemic area along the Thai-Myanmar border: A health systems perspective.

Despite Thailand's progress under the 1-3-7 malaria elimination framework, border districts such as Tha Song Yang in Tak Province continue to experience persistent transmission due to high population mobility, geographic constraints, and health system challenges. Understanding how local health systems respond to these pressures is critical for sustaining malaria elimination in complex border settings. This mixed-methods study applied the World Health Organization's Six Building Blocks framework to examine challenges and responses in malaria elimination in Tha Song Yang District. Qualitative data were collected through in-depth interviews with 24 key informants from district health offices, vector-borne disease units, malaria posts and clinics, hospitals, and local authorities. Quantitative data included household surveys assessing malaria-related knowledge, attitudes, and practices (n = 388), and secondary surveillance data on adherence to the 1-3-7 strategy from 2018 to 2022. Adherence to Day 1 and Day 3 activities improved steadily, reaching 96% and 100%, respectively, while Day 7 adherence declined sharply to 69% in 2022. The household survey showed high levels of malaria knowledge (75.77%) and positive attitudes toward prevention (94.59%), indicating that community awareness was strong despite ongoing transmission. Qualitative findings highlighted a surge of short-term migrants, workforce shortages, reduced domestic funding, and logistical barriers in remote areas as key constraints, while adaptive local responses-including local flexibility, committed leadership, and the use of the Malaria Information System and mobile communication platforms-helped sustain malaria control and surveillance activities. These findings demonstrate that malaria persistence in border areas is driven primarily by systemic and operational challenges rather than gaps in community awareness. Strengthening malaria elimination in similar border settings requires resilient health systems with sustained domestic financing, adaptive surveillance strategies, effective use of digital tools, and governance arrangements that account for population mobility and cross-border complexity.