Investigating behavioral drivers of seasonal Shiga-Toxigenic Escherichia Coli (STEC) patterns in grazing cattle using an agent-based model

Authored by Cristina Lanzas, Daniel E Dawson, Jocelyn H Keung, Monica G Napoles, Michael R Vella, Shi Chen, Michael W Sanderson

Date Published: 2018

DOI: 10.1371/journal.pone.0205418

Sponsors: United States Department of Agriculture (USDA) United States National Institutes of Health (NIH) United States Department of Homeland Security United States National Science Foundation (NSF)

Platforms: NetLogo

Model Documentation: ODD Flow charts Mathematical description

Model Code URLs: https://doi.org/10.1371/journal.pone.0205418.s003

Abstract

The causes of seasonal variability in pathogen transmission are not well understood, and have not been comprehensively investigated. In an example for enteric pathogens, incidence of Escherichia coli O157 (STEC) colonization in cattle is consistently higher during warmer months compared to cooler months in various cattle production systems. However, actual mechanisms for this seasonality remain elusive. In addition, the influence of host (cattle) behavior on this pattern has not been thoroughly considered. To that end, we constructed a spatially explicit agent-based model that accounted for the effect of temperature fluctuations on cattle behavior (direct contact among cattle and indirect between cattle and environment), as well as its effect on pathogen survival in the environment. We then simulated the model in a factorial approach to evaluate the hypothesis that temperature fluctuations can lead to seasonal STEC transmission dynamics by influencing cattle aggregation, grazing, and drinking behaviors. Simulation results showed that higher temperatures increased the frequency at which cattle aggregated under shade in pasture, resulting in increased direct contact and transmission of STEC between individual cattle, and hence higher incidence over model simulations in the warm season. In contrast, increased drinking behavior during warm season was not an important transmission pathway. Although sensitivity analyses suggested that the relative importance of direct vs. indirect (environmental) pathways depend to upon model parameterization, model simulations indicated that factors influencing cattle aggregation, such as temperature, were likely strong drivers of transmission dynamics of enteric pathogens.

Tags

Prevalence transmission Climate-change Infectious-diseases Survival Temperature-dependence Beef-cattle Coli o157-h7 Heat-stress O157h7