Like zoonotic diseases which have captured the world’s attention—including SARS diseases, such as Covid-19—drug resistant malaria is widely viewed as a threat emerging in Asia. This essay explores how scientists and policy makers act within this discourse, which shapes their work and the allocation of scarce health resources in Cambodia. Questions about the ethics and politics of science come to the fore when the Greater Mekong subregion is an experimental site of elimination for other places where malaria is endemic. It demands innovative ways of doing “region,” following scientists’ conceptions of the “Greater Mekong subregion,” but also centering how borderlands are unique and important areas for the development of resistance. Africa-Southeast Asia relations are center stage, too, producing, I suggest, a region that is not geographically contiguous yet entangled through research, parasites, postcolonial conflict, and the biographies of scientists and health professionals.