Zoonotic malaria in Southeast Asia's changing landscapes: vector complexity, challenges, and future strategies.

Zoonotic malaria, particularly Plasmodium knowlesi, has emerged as a growing public health concern across Southeast Asia, with increasing incidence reported in multiple countries. The recent detection of additional zoonotic Plasmodium species further complicates the epidemiological landscape, underscoring the expanding interface among humans, wildlife reservoirs, and mosquito vectors. Despite this trend, progress towards effective control and elimination remains limited, largely due to substantial gaps in entomological knowledge across many endemic regions. Currently, only a narrow range of vector control approaches is available, and these strategies are often ill-suited to the ecological and behavioural characteristics of zoonotic malaria transmission. A major challenge lies in the complexity of vector species assemblages in Southeast Asia. Some of the vectors belong to species complexes with high morphological similarity, making accurate taxonomic identification difficult. Misidentification of mosquito species can distort assessments of vector competence, biting behaviour, and ecological niche, leading to inaccurate inferences about transmission dynamics and potentially resulting in ineffective surveillance and misdirected vector control interventions. Compounding this issue are rapid landscape changes driven by deforestation, agricultural expansion, and habitat fragmentation, which alter mosquito bionomics. Growing evidence suggests that such environmental disturbances may promote outdoor and forest-associated biting, enhance vector adaptability, and shift transmission risk toward human settlements. Thus, this review synthesises current knowledge on the ecological, behavioural, and taxonomic complexities of zoonotic malaria vectors within a rapidly changing landscape. By critically examining challenges in vector identification, surveillance, and control, we highlight key gaps that impede effective intervention. Finally, we discuss pathways forward, emphasising the need for integrated, context-specific, and One Health-oriented strategies to address the unique challenges posed by zoonotic malaria transmission in Southeast Asia.