Ecological Approaches to Studying Zoonoses

EcoHealth and One Health: A theory-focused review in response to calls for convergence

BACKGROUND

EcoHealth and One Health are two major approaches broadly aimed at understanding the links between human, animal, and environment health. There have been increasing calls for convergence between the two. If convergence is desired, greater clarity regarding the underlying theoretical assumptions of both approaches is required. This would also support integrated research to effectively address complex health issues at the human, animal and environment interface. To better understand the areas of overlap and alignment, we systematically compared and contrasted the theoretical assumptions of both approaches.

OBJECTIVES

We aimed to gain a more in-depth understanding of the ontological, epistemological and methodological underpinnings of EcoHealth and One Health in order to identify areas of difference and overlap, and consider the extent to which closer convergence between the two may be possible.

METHODS

We undertook a scoping review of literature about the ontological, epistemological and methodological positions of EcoHealth and One Health, and analyzed these according to Lincoln, Lynham and Guba's paradigm framework.

RESULTS

EcoHealth and One Health are both collaborative, systems-focused approaches at the human, animal, and ecosystem health interface. EcoHealth typically leans towards constructivist-leaning assumptions. Many consider this a necessary aspiration for One Health. However, in practice One Health remains dominated by the veterinary and medical disciplines that emphasize positivist-leaning assumptions.

DISCUSSION

The aspirations of EcoHealth and One Health appear to overlap at the conceptual level, and may well warrant closer convergence. However, further shared discussions about their epistemological and ontological assumptions are needed to reconcile important theoretical differences, and to better guide scopes of practice. Critical realism may be a crucial theoretical meeting point. Systems thinking methods (with critical realist underpinnings), such as system dynamics modelling, are potentially useful methodologies for supporting convergent practice.

Zoonotic Potential of Emerging Paramyxoviruses: Knowns and Unknowns

The risk of spillover of enzootic paramyxoviruses and the susceptibility of recipient human and domestic animal populations are defined by a broad collection of ecological and molecular factors that interact in ways that are not yet fully understood. Nipah and Hendra viruses were the first highly lethal zoonotic paramyxoviruses discovered in modern times, but other paramyxoviruses from multiple genera are present in bats and other reservoirs that have unknown potential to spillover into humans. We outline our current understanding of paramyxovirus reservoir hosts and the ecological factors that may drive spillover, and we explore the molecular barriers to spillover that emergent paramyxoviruses may encounter. By outlining what is known about enzootic paramyxovirus receptor usage, mechanisms of innate immune evasion, and other host-specific interactions, we highlight the breadth of unexplored avenues that may be important in understanding paramyxovirus emergence.