examples in the categories of ‘One Health and Conservation Medicine’, ‘Ecosystem Approaches to Health’ and ‘Public Health, Ecosystems and Society’. The broad definition is similar to the conception of One Health, as a field that addresses ‘interactions between human and animal health that reach far beyond individual clinical issues and include ecology, public health and broader societal dimensions’(Zinsstag et al., 2011, p. 3). In practical terms, this can be framed as the ‘added value [in terms of improved human and animal health outcomes, and ecosystem services] of a closer cooperation of human and animal health and other sectors’(Zinsstag et al., 2012, p. 2).
We situate our discussion in this chapter within this broad definition of the field of ecohealth, which we are taking to encompass One Health as described in this volume. As discussed in some earlier chapters, One Health has come to be seen by many researchers and practitioners as a strategy for achieving, jointly, animal and human health outcomes that would not be possible, or if possible would be more costly and/or less effective, if undertaken by separate initiatives. The selection of outcomes, and their sustainability, are embedded in much larger and complex social-ecological systems. Grappling with the challenges of understanding this broader context is the subject matter for ecohealth.
To some applied researchers, public and animal health experts and development practitioners, ‘ecohealth’ has a more specific connotation. They refer to the ‘ecohealth approach’ or the ‘ecosystem approach to health and well-being’. This is an approach that began to emerge in the 1990s with: (i) the expression of an ecosystem approach rooted in systems thinking, conceptualizing coupled human and natural systems, operated by collaborative processes and intended to intervene in situations of complexity and uncertainty (e.g. Allen et al., 1994; Kay and Sneider, 1994; Bunch, 2001; Waltner-Toews and Kay, 2005; Waltner-Toews et al., 2008); and (ii) its application to social-ecological systems for the purpose of improving human health and well-being (e.g. Yassi et al., 1999; Forget and Lebel, 2001; Waltner-Toews, 2001; Murray et al., 2002; De Plaen and Kilelu, 2004; Bunch et al., 2006; Boischio et al., 2009; Webb et al., 2010; Charron, 2012; Bunch, 2016; in the 2017 special issue of Acta Tropica on ‘Ecohealth: an African Perspective’; and Zinsstag et al., Chapter 2, this volume).
The ecohealth approach is an applied and action-oriented approach intended to both improve understanding about a situation and intervene to benefit human health and well-being. To date it has mostly been applied in development contexts in the Global South, because of the origins of the approach with a development funding agency in Canada: the International Development Research Centre (IDRC). Dominique Charron, currently Vice President of IDRC, and, for more than a decade, the director of programmes related to ecosystems and human health, defined ecohealth as an approach that:
formally connect[s] ideas of environmental and social determinants of health with those of ecology and systems thinking in an action-research framework applied mostly within a context of social and economic development. Ecosystem approaches to health focus on the interactions between the ecological and socio-economic dimensions of a given situation, and their influence on human health, as well as how people use or impact ecosystems, the implications for the quality of ecosystems, the provision of ecosystem services, and sustainability.
(Charron, 2012, p. 6)
A wide range of researchers, practitioners and teachers have been involved in developing and applying the ecohealth approach, especially those associated with IDRC’s Program Initiative in Ecosystem Approaches to Human Health, the Ecohealth Alliance, Veterinarians without Borders/Vétérinaires Sans Frontières (VWB/VSF) (https://www.vetswithoutborders.ca/ (accessed 3 June 2020)),1 members of the International Association for Ecology and Health and Ecohealth International. Many of these organized into communities of practice in ecosystem approaches to health, in Canada, West Africa, South-east and East Asia, Latin America and the Caribbean (for example see www.copeh-canada.org (accessed 3 June 2020)). Several published training manuals for use in South-east Asia and North America (e.g. McCullagh et al., 2012; Parkes et al., 2017). The websites of these organizations and the journal EcoHealth showcase some examples of applications and development of theory and methods associated with the ecohealth approach.
In this chapter we discuss the nature of the problems that the ecohealth approach is intended to address. We present an overview of the ecosystem approach, a transdisciplinary conception of health, and principles and guidelines that bring these together in the ecosystem approach to health and well-being.
Positioning Ecohealth
For ease of communication ecohealth is sometimes described as an approach to managing environmental and social determinants of health. This is misleading because it implies a linear sequence of simple determinants and that intervention somewhere along that line will improve health. The situations to which the ecohealth approach is most appropriate are instead characterized by multiple diffuse pathways that are difficult to identify and parse, and by relationships that are self-reinforcing and resistant to change. Yet they may be subject to sudden and surprising reorganization resulting from what seem to be simple interventions.
This is because coupled human and natural systems are not merely complicated – they are complex. Complex systems do not behave like machines, with parts connected by causally linear relationships. Instead they are dominated by feedback loops that lead to self-organization and evolutionary behaviour, they have interacting, multi-scalar hierarchical settings, they adapt and evolve, and they are characterized by irreducible uncertainty.2
Such situations tend to defeat our normal approach to problem solving. Since the scientific revolution of the 17th century, we have been trained to deal with problems that can be compartmentalized, isolated and reduced to manageable cause–effect relationships. Furthermore, our institutions (health authorities, planning departments, etc.) are structured and operate in this old paradigm (Bavington, 2002; Berkes, 2003; Innes and Booher, 2010). Because the application of ‘normal science’ (described by
