Mapping Brucellosis Increases Relative to Elk Density using Hierarchical Bayesian Models

Scientific Disciplines
Biological Sciences - Terrestrial
Montana State University
Greater yellowstone ecosystem
Department of Ecology
Northern Rocky Mountain Science Center
Animal diseases
Feeding grounds
Artificial feeding
National Wildlife Health Center
hierarchical bayesian
elk density
wyoming game fish
montana state university bozeman
wyoming game fish department
Volume 16, No. 4

Mapping brucellosis increases relative to elk density using 
hierarchical bayesian models 

Paul C. Cross*  U.S. Geological Survey, Northern Rocky Mountain Science Center, 2327 
University Way, Suite #2, Bozeman Montana 59715 
D. M. Heisey  U.S. Geological Survey, National Wildlife Health Center, Madison, Wisconsin 53711 
B. M. Scurlock, Wyoming Game and Fish Department, PO Box 850, Pinedale, Wyoming 82941 
W. H. Edwards,  Wyoming Game and Fish Department, 1174 Snowy Range Rd, Laramie, Wyoming 
M. R. Ebinger, Big Sky Institute, Montana State University, Bozeman Montana 59717 
A. Brennan, Department of Ecology, Montana State University, Bozeman Montana 59717 
The relationship between host density and parasite transmission is central to the 
effectiveness of many management strategies. We applied hierarchical Bayesian methods to 
an 18-yr dataset on elk (Cervus elaphus) brucellosis in the Greater Yellowstone Ecosystem 
(GYE) and found that increases in brucellosis seroprevalence were strongly correlated with 
elk densities. Elk that were densely aggregated on supplemental feeding grounds had higher 
seroprevalence in 1991, but by 2008 many areas distant from the feeding grounds were of 
comparable seroprevalence. Thus, brucellosis appears to be expanding its range into areas 
of higher elk density, which is likely to further complicate the United States brucellosis 
eradication program. The data could not differentiate among linear and non-linear effects of 
host density, which is a critical area where research can inform management actions. This 
study is an example of how the dynamics of host populations can affect their ability to serve 
as disease reservoirs.