Epidemiological modeling of SARS-CoV-2 in white-tailed deer (Odocoileus virginianus) reveals conditions for introduction and widespread transmission

Abstract

Emerging infectious diseases with zoonotic potential often have complex socioecological dynamics and limited ecological data, requiring integration of epidemiological modeling with surveillance. Although our understanding of SARS-CoV-2 has advanced considerably since its detection in late 2019, the factors influencing its introduction and transmission in wildlife hosts, particularly white-tailed deer (Odocoileus virginianus), remain poorly understood. We use a Susceptible-Infected-Recovered-Susceptible epidemiological model to investigate the spillover risk and transmission dynamics of SARS-CoV-2 in wild and captive white-tailed deer populations across various simulated scenarios. We found that captive scenarios pose a higher risk of SARS-CoV-2 introduction from humans into deer herds and subsequent transmission among deer, compared to wild herds. However, even in wild herds, the transmission risk is often substantial enough to sustain infections. Furthermore, we demonstrate that the strength of introduction from humans influences outbreak characteristics only to a certain extent. Transmission among deer was frequently sufficient for widespread outbreaks in deer populations, regardless of the initial level of introduction. We also explore the potential for fence line interactions between captive and wild deer to elevate outbreak metrics in wild herds that have the lowest risk of introduction and sustained transmission. Our results indicate that SARS-CoV-2 could be introduced and maintained in deer herds across a range of circumstances based on testing a range of introduction and transmission risks in various captive and wild scenarios. Our approach and findings will aid One Health strategies that mitigate persistent SARS-CoV-2 outbreaks in white-tailed deer populations and potential spillback to humans.

Cross-sector collaboration is more effective than single sector actions at mitigating SARS-CoV-2 in white-tailed deer

“…For wild deer, the same panel estimated that suburban settings had 2.7 times higher proximity rates when compared to rural and ranch (captive) deer 9 (Supplementary Table 3). Despite these differences, Rosenblatt et al (2023) 8 found that simulated disease outcomes had low sensitivity across the range of human-to-deer spillover rates, suggesting that infrequent human-to-deer transmission events are sufficient to initiate sustained outbreaks in deer. Deer-to-deer transmission, however, was sensitive to parameter values.…”

“…Deer are assumed to be evenly distributed with all individuals subjected to the same contact rates. We parameterized the model to simulate the midwestern U.S. during the fall season (September-December; 120-day window) when humans may contact deer during hunting and other activities and acquired parameter estimates using empirical data and expert elicitation 8 (Supplementary Table 3).…”

“…We then developed a deterministic compartmental disease model that could test the efficacy of these alternatives in a simulated system where humans, wild and captive deer could interact (Rosenblatt et al 2023 for details). The model allows captive and wild deer to transition among susceptible (s), infectious (i), and recovered (r) compartments before eventually returning to the susceptible compartment.…”

“…Second, we developed and used a deterministic compartmental model to evaluate spillover and spread rates in isolated deer herd settings, and to estimate prevalence, incidence, and persistence in a range of connected human-deer scenarios. Here, we focus on evaluating the decision space of the One Health collaborative using a model that was developed and described in detail in Rosenblatt et al (2023) 8 . Collectively, our decision analysis and risk modeling efforts can guide agencies with purview over risk mitigation to make data-driven, transparent, and reproducible decisions that help meet their fundamental objectives.…”

“…Second, we developed and used a deterministic compartmental model to evaluate spillover and spread rates in isolated deer herd settings, and to estimate prevalence, incidence, and persistence in a range of connected humandeer scenarios. Here, we focus on evaluating the decision space of the One Health collaborative using a model that was developed and described in detail in Rosenblatt et al (2023) 8 .…”