Context-dependent host dispersal and habitat fragmentation determine heterogeneity in infected tick burdens: an agent-based modelling study

Abstract

As the incidence of tick-borne diseases has sharply increased over the past decade, with serious consequences for human and animal health, there is a need to identify ecological drivers contributing to heterogeneity in tick-borne disease risk. In particular, the relative importance of animal host dispersal behaviour in its three context-dependent phases of emigration, transfer and settlement is relatively unexplored. We built a spatially explicit agent-based model to investigate how the host dispersal process, in concert with the tick and host demographic processes, habitat fragmentation and the pathogen transmission process, affects infected tick distributions among hosts. A sensitivity analysis explored the impacts of different input parameters on infected tick burdens on hosts and infected tick distributions among hosts. Our simulations indicate that ecological predictors of infected tick burdens differed among the post-egg life stages of ticks, with tick attachment and detachment, tick questing activity and pathogen transmission dynamics identified as key processes, in a coherent way. We also found that the type of host settlement strategy and the proportion of habitat suitable for hosts determined super-spreading of infected ticks. We developed a theoretical mechanistic framework that can serve as a first step towards applied studies of on-the-ground public health intervention strategies.

Towards a Generic Agent Based Vector-Host Model

“…Prior studies have underscored the importance of agent-based modelling in elucidating the complexities of vectorhost systems (e.g. [10,20,24]). These studies have predominantly focused on landscape characteristics, particular tick species, and host-specific models.…”

“…[16,23], host-vector-pathogen (e.g. [20,24,25,26]), or host-pathogen systems (refer to [27]). Simulation models are increasingly being used to solve problems and aid in decision-making in agricultural systems [28] and veterinary epidemiological systems [16] as well as in public health systems [14].…”

IxPopDyMod: an R package to write, run, and analyze tick population and infection dynamics models

“…The model assumes well-mixed, spatially homogeneous tick and host populations. It does not have a built-in structure to model landscapes made up of a fraction of different habitat types [ 7 , 28 , 29 ] or a spatially explicit structure [ 19 , 30 ]. Still, it would be possible for the user to, for example, run the model on “patches” with and “migrate” ticks between them.…”

Combining epidemiology and economics to assess control of a viral endemic animal disease: Porcine Reproductive and Respiratory Syndrome (PRRS)

“…Mathematical models can be used to simulate the spread of crop, animal, or human diseases, to shed light on disease dynamics and analyze the effects of different control strategies [11]. For example, Tardy et al (2022) used an agent-based spatial model to investigate how host distribution and habitat fragmentation affect the dynamics of tick-borne diseases. The authors concluded that the host settlement strategy and the proportion of habitat available to hosts determined the super-spread of infected ticks, which could be relevant to designing public health interventions to control tick-borne diseases [12].…”

“…For example, Tardy et al (2022) used an agent-based spatial model to investigate how host distribution and habitat fragmentation affect the dynamics of tick-borne diseases. The authors concluded that the host settlement strategy and the proportion of habitat available to hosts determined the super-spread of infected ticks, which could be relevant to designing public health interventions to control tick-borne diseases [12]. Although the dynamics of the disease are complex, various studies on COVID-19 diffusion modeling have been published to help design public health strategies [13][14][15][16][17].…”