This article introduces the Parasiteissue dedicated to part of the research in social sciences supported by the Domaine d’Intérêt Majeur de la Région Île-de-France(DIM) One Health [2016–2022]. We show how the four papers of this special issue are related. Jérôme Michalon recalls the genealogy of One Health and analyzes it as an “epistemic watchword”. Using antibiotic resistance as a case study, Estera Badau demonstrates how “One Health” results from a series of formulas and the bringing together of a plurality of fields and actors. Nicolas Lainé and Serge Morand show how One Health fits in with attempts already initiated in the colonial period and context. They highlight the need to (re)legitimize local and non-human knowledge, in order to truly decolonize One Health and better prevent epidemic emergence. Finally, Frédéric Keck, Nicolas Lainé, Arnaud Morvan and Sandrine Ruhlmann show how zoonotic reservoir and cultural practices are linked in the context of three specific societies. This paper highlights two main contributions of social sciences: 1) To think about One Health genealogy, how the question is framed and by which actors. The questions of practices, social representations but also of the environment are less present than the issues of human and animal medicine. The Anthropocene, the Capitalocene, even some of its variations such as the “domesticoscene” thus appear to be key elements. 2) To propose methods and tools that make One Health operational, advocating a less asymmetrical view of types of knowledge (scientific, local, non-human) and more contextualized global health recommendations.