Defining One Health: Environment versus ecosystem

Abstract Background : This article seeks greater precision in defining One Health by clarifying ambiguities and elaborating issues that arise from the One Health High-Level Expert Panel (OHHLEP) definition, while acknowledging the utility of the OHHLEP definition and the consensus it represents. In particular, we clarify certain implications of how the third, environmental component of One Health is understood. Methods : We developed our argument by taking part in the interdisciplinary Science Advice for Policy by European Academies (SAPEA) consortium for One Health Governance in the European Union. We are a highly interdisciplinary team that has developed this theoretical position by meeting throughout 2024 to write the report chapter on which it is based. Results : We suggest that whereas an “environment” implies something external (and perhaps subordinate) to humans and animals, an “ecosystem” implies a system of which both humans and animals are part (alongside plants, chemicals, microbes, etc.). We explore three sets of concepts within the OHHLEP definition: “integrated” and “unifying”; “balanced” and “optimised”; “closely linked”; and “interdependent.” Lastly, we explain our synergies and complementarity with adjacent concepts including “Planetary Health”. Conclusions : To us, clarity in these nuances seems key in the development of One Health away from an anthropocentric framing towards a more integrated and balanced framing. While we argue that the ecosystemic, holistic view is preferable and better aligned with One Health’s expanding scope, we note that conditions for making practical changes are not yet able to accommodate holism. One Health impact statement Defining a concept is an opportunity to work through contradictions and imprecisions that can hinder practical application. The concept of One Health is transformative and complex. While substantial attention has been given to defining it, ambiguities remain. In addition to possible conflicts and frictions in applying One Health principles, these ambiguities have political and ethical stakes. Fully integrating the third principle of environmental health and granting it as much attention and importance as human and animal health is a challenge with practical and ethical/political dimensions. The conceptual work in this article will help implement One Health and realise its added value potential. It is transdisciplinary in that it was developed by a highly interdisciplinary group of scholars, spanning humanities/social sciences (philosophy, anthropology, legal studies, public health), and biological sciences (veterinary medicine, parasitology), all of whom are engaged with clinical practice, policy making, and/or community-based work.