Spatial and Temporal Dynamics of Prion Disease in Wildlife: Responses to Changing Land Uses

Principal Investigator: Tom Hobbs - Colorado Division of Wildlife and NREL

Unit Investigator: Ken Burnham

Funding Agency: NIH and NSF

Introduction: Chronic wasting disease (CWD) of the deer family is a transmissible spongiform encephalopathy, a member of a group of infectious diseases affecting animals and people known as prion diseases. The only region in the world where prion diseases are known to occur in free-ranging animals is northeastern Colorado and southeastern Wyoming, where an epidemic of CWD has been ongoing for at least two decades. These naturally infected populations offer a unique opportunity to understand the transmission dynamics of a disease that has potentially enormous consequences for wildlife and that could threaten human health and human economies over large areas.

Changes in land-use in the epidemic area are fragmenting and compressing habitats for deer. We hypothesize that these changes could accelerate a spread of the disease. Here, we propose studies to expand understanding CWD transmission mechanisms and to develop predictive models of disease dynamics. We will describe mechanisms of CWD transmission between infected and susceptible individuals and determine if environmental sources of infectious PrPCWD can contribute to disease transmission. We will develop best approximating models of disease dynamics and will use these models to investigate anthropogenic effects of habit compression and fragmentation resulting from sustained changes in human land-use. To meet these aims, we conduct controlled experiments using transgenic mice as models to illuminate mechanisms of transmission. We will use 15 years of data on CWD prevalence in selected mule deer populations to choose best approximating models of disease dynamics. We will use these models to project likely trajectories of the disease in the face of dramatic anthropogenic environmental change and to evaluate strategies for management.

Objectives: Understand chronic wasting disease and its effects in mule deer; this will assist CDOW in management of CWD. Burnham’s participation is about various statistical issues.

Progress: Ongoing.

Plans: Burnham will continue to work with the team on this CWD project. That team includes people from CDOW and CSU.

Results/Products: Wolfe, L. L., M. M. Conner, T. H. Baker, V. J. Dreitz, K. P. Burnham, E. S. Williams, N. T. Hobbs, and M. W. Miller. 2002. Evaluation of antemortem sampling to estimate chronic wasting disease prevalence in free-ranging mule deer. Journal of Wildlife Management 66564-573. Presumable you will delete this and just show results from the past year. Hence, new:

Farnsworth, M. L., Wolfe, L.L., Hobbs, N. T., Burnham, K. P., and Miller, M. W. (in review). Human land use influences chronic wasting disease prevalence in mule deer. Ecological Applications.