Dynamic, spatial models of parasite transmission in wildlife: Their structure, applications and remaining challenges

Abstract

Individual differences in contact rate can arise from host, group and landscape heterogeneity and can result in different patterns of spatial spread for diseases in wildlife populations with concomitant implications for disease control in wildlife of conservation concern, livestock and humans. While dynamic disease models can provide a better understanding of the drivers of spatial spread, the effects of landscape heterogeneity have only been modelled in a few well-studied wildlife systems such as rabies and bovine tuberculosis. Such spatial models tend to be either purely theoretical with intrinsic limiting assumptions or individual-based models that are often highly species- and system-specific, limiting the breadth of their utility. Our goal was to review studies that have utilized dynamic, spatial models to answer questions about pathogen transmission in wildlife and identify key gaps in the literature. We begin by providing an overview of the main types of dynamic, spatial models (e.g., metapopulation, network, lattice, cellular automata, individual-based and continuous-space) and their relation to each other. We investigate different types of ecological questions that these models have been used to explore: pathogen invasion dynamics and range expansion, spatial heterogeneity and pathogen persistence, the implications of management and intervention strategies and the role of evolution in host-pathogen dynamics. We reviewed 168 studies that consider pathogen transmission in free-ranging wildlife and classify them by the model type employed, the focal host-pathogen system, and their overall research themes and motivation. We observed a significant focus on mammalian hosts, a few well-studied or purely theoretical pathogen systems, and a lack of studies occurring at the wildlife-public health or wildlife-livestock interfaces. Finally, we discuss challenges and future directions in the context of unprecedented human-mediated environmental change. Spatial models may provide new insights into understanding, for example, how global warming and habitat disturbance contribute to disease maintenance and emergence. Moving forward, better integration of dynamic, spatial disease models with approaches from movement ecology, landscape genetics/genomics and ecoimmunology may provide new avenues for investigation and aid in the control of zoonotic and emerging infectious diseases.

A mechanistic, stigmergy model of territory formation in asocial animals: Territorial behavior can dampen disease prevalence but increase persistence

“…Mechanistic portrayals of how animals form and maintain territories remain rare, and to our knowledge, have not been integrated with a disease modeling framework. This work provides a key interface between the disciplines of movement and disease ecology [4,5,13] by exploring how mechanistic movement driven by an individual's social landscape affects disease dynamics. These results indicate an interesting threshold at higher host densities where stigmergy-driven movement behavior can still support pathogen persistence.…”

“…In contrast, mechanistic portrayals of how animals form and maintain territories remain rare [9] (but see: [10][11][12]). Disease ecology faces similar barriers to incorporating contact behavior that explicitly reflects individual movement patterns [4,5,13]. Models in disease ecology are often specific to a given-host pathogen system or emphasize the risk of contact rather than ongoing transmission dynamics [5].…”

And the winner of the inaugural Sidnie Manton Award is…

“… Jenni McDonald and colleagues’ (2018) Synthesis on host‐pathogen systems of a naturally infected badger population (McDonald, Robertson, and Silk, ). Kristine Grayson's (2018) Synthesis of the population dynamics and invasion biology of gypsy moths in the US (Grayson and Johnson ). Lauren White and colleagues’ (2018) Review of spatial models of parasite transmission in wildlife (White, Forester, and Craft ). Quinn Webber's (2018) Review integrating the ecological and evolutionary implications of individual social and spatial behaviour (Webber and Vander Wal ). Ben Weinstein's (2018) Review of a computer vision for animal ecology (Weinstein ). Pratha Sah's () Review on disease implications of animal social network structure (Sah, Mann, & Bansal, 2018). …”

“…Grayson's (2018) Synthesis of the population dynamics and invasion biology of gypsy moths in the US (Grayson and Johnson 2018). ' (2018) Review of spatial models of parasite transmission in wildlife (White, Forester, and Craft 2018). Webber's (2018) Review integrating the ecological and evolutionary implications of individual social and spatial behaviour (Webber and Vander Wal 2018).…”

Quantifying direct and indirect contacts for the potential transmission of infection between species using a multilayer contact network

“…The application of network approaches (Silk et al, 2017a,b;White et al, 2017) and movement ecology (Dougherty et al, 2018;White et al, 2018) has become integral to understanding the impact of individual behaviour in disease ecology. Both approaches have exploited the increasing availability of high resolution bio-logging technology to quantify how variation in host behaviour contributes to heterogeneity in pathogen transmission opportunities (Krause et al, 2013;White et al, 2017).…”