Malaria in Menoreh Hills, Indonesia: an eco-epidemiological perspective on persistence of malaria transmission.

Persistent malaria transmission remains a considerable challenge in Indonesia despite national elimination efforts, with the Menoreh Hills representing a residual transmission hotspot characterized by ecological and socio-behavioral complexity. This highland region, spanning the boundaries of the Kulon Progo, Purworejo, and Magelang districts presents a complex eco-epidemiological setting in which malaria transmission persists despite substantial reductions in incidence. Spatial analyses consistently reveal micro-foci and cross-district clusters, underscoring the structural and ecological interconnectedness of the Menoreh Hills, including Anopheles mosquito habitats. Anopheles mosquitoes exhibit ecological adaptability and behavioral plasticity that may contribute to residual transmission. This region features a heterogeneous landscape of secondary forests, agricultural lands, and rural settlements that foster diverse vector species and habitats, occupational exposure, and sustained human-vector contact associated with Plasmodium transmission. Hypnozoite-mediated relapse in P. vivax, prolonged gametocyte carriage in P. falciparum, and asymptomatic or submicroscopic infections may contribute to residual transmission. Surveillance is complicated by fragmented governance, variable funding, high human mobility across district borders, and logistical constraints imposed by rugged topography. This review emphasizes the necessity of strengthening integrated malaria surveillance systems that combine entomological, serological, genomic, and spatial data to enable early detection and targeted interventions. Cross-sectoral collaboration, community engagement, and adaptive, location-specific strategies addressing socio-ecological determinants alongside biological and environmental drivers are essential to interrupt persistent transmission in complex residual foci such as the Menoreh Hills.