Modeling elk-to-livestock transmission risk to predict hotspots of brucellosis spillover

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Modeling elk-to-livestock transmission risk to predict hotspots of brucellosis spillover


Wildlife reservoirs of infectious disease are a major source of human-wildlife conflict because of the risk of potential spillover associated with commingling of wildlife and livestock. In the Greater Yellowstone Ecosystem, the presence of brucellosis (Brucella abortus) in free-ranging elk (Cervus canadensis) populations is of significant management concern because of the risk of disease transmission from elk to livestock. We identified how spillover risk changes through space and time by developing resource selection functions using telemetry data from 223 female elk to predict the relative probability of female elk occurrence daily during the transmission risk period. We combined these spatiotemporal predictions with elk seroprevalence, demography, and transmission timing data to identify when and where abortions (the primary transmission route of brucellosis) were most likely to occur. Additionally, we integrated our predictions of transmission risk with spatiotemporal data on areas of potential livestock use to estimate the daily risk to livestock. We predicted that approximately half of the transmission risk occurred on areas where livestock may be present (i.e., private property or grazing allotments). Of the transmission risk that occurred in livestock areas, 98% of it was on private ranchlands as opposed to state or federal grazing allotments. Disease prevalence, transmission timing, host abundance, and host distribution were all important factors in determining the potential for spillover risk. Our fine-resolution (250-m spatial, 1-day temporal), large-scale (17,732 km2) predictions of potential elk-to-livestock transmission risk provide wildlife and livestock managers with a useful tool to identify higher risk areas in space and time and proactively focus actions in these areas to separate elk and livestock to reduce spillover risk.

Bibliographic Citation

Rayl, N.D., K.M. Proffitt, E.S. Almberg, J.D. Jones, J.A. Merkle, J.A. Gude, and P.C. Cross. 2019. Modeling elk-to-livestock transmission risk to identify hotspots of brucellosis spillover. The Journal of Wildlife Management 83:817-829.


Rayl, Nathaniel D.
Proffitt, Kelly M.
Almberg, Emily S.
Jones, Jennifer D.
Merkle, Jerod A.
Gude, Justin A.
Cross, Paul C.


Brucella abortus
Cervus canadensis
Cross-species pathogen spillover
Greater Yellowstone Ecosystem
Habitat selection
Human-wildlife conflict
Resource selection function
Wildlife disease


13 pages

Date Created








Is Part Of

The Journal of Wildlife Management



Rayl, Nathaniel D. et al., “Modeling elk-to-livestock transmission risk to predict hotspots of brucellosis spillover,” CPW Digital Collections, accessed June 22, 2024,