A Risk Management of Chronic Wasting Disease Outbreak in New York State

NON-TECHNICAL SUMMARY: Because prion diseases are a relatively new discovery, and because CWD is the first known prion disease to occur in free-ranging animals, we find ourselves in largely uncharted waters when faced with the predictions, consequences, and management strategies required of infected populations. We need to be able to predict the patterns and influences of a disease with potentially devastating consequences to wildlife populations, human health, and the State's economy. We intend to provide a risk assessment model that can be used to evaluate the impacts of a CWD outbreak on New York State's big game industry, and inform allocation of resources to monitoring and management of the disease.

<P>APPROACH: We intend use Geograpic Information Systems (GIS) to develop time series risk assessment maps of potential routes of disease transmission by identifying various large-scale, geographical factors that may influence the spread of disease. These factors include, but are not limited to deer density and distribution, location of cervid farms, focus points of disease entry, location of livestock and developed areas, identification of geographical barriers and potential disease reservoirs, and degree of fragmentation on the landscape.
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PROGRESS: 2005/08 TO 2008/09<BR>
OUTPUTS: 1. We deployed 125 GPS collars in 2 study areas of central New York (NYSDEC Regions 6 and 7), and an additional 22 collars in the central Adirondacks (Region 5). 2. We evaluated the spatial scale at which deer appear to perceive the landscape and the characteristics of land cover composition and configuration that influence the amount of space and specific cover-types used within and among seasons. 3. We evaluated temporal and spatial dynamics of both direct and indirect rates of contact among individuals across a range of geographic scales. 4. We mapped the geographic distribution of risk of spread of disease in terms of probability of contact among deer from a point of occurrence. We further classified land cover within this distribution in terms of probability of use and potential for long-term contamination by prions. 5. We compared use of space by deer between the agriculture-forest matrix of central New York and the contiguous, mountainous forest region of northern New York and outlined management implications for both regions. 6. We evaluated the potential for extension of the model to other areas of New York. <BR> PARTICIPANTS: William Porter, PI, Professor; Amy Dechen Quinn, Doctoral Student; David Williams, Doctoral Student; Matthew Smith, Masters Student; Frank DeSantis, Masters Student; Brigham Whitman, Masters Student; New York State Department of Environmental Conservation; US Geological Survey; SUNY-ESF TARGET AUDIENCES: New York State Department of Environmental Conservation; Scientific Community <P>
IMPACT: 2005/08 TO 2008/09<BR>
Space use by deer varies along a gradient of fragmentation. Land-cover composition is dominated by forest and ratios of forest, agriculture and rangeland are consistently about 2:1:1. Home ranges are smaller in areas where landscape patches are highly fragmented, patch richness is high and where there is a mixture of large and small patches. Our findings show that both daily direct and indirect contact probabilities vary through the year in a form approximating a sine curve, with daily indirect contact probabilities nearly 3 times greater than direct contact probabilities. The probability of contact among individuals peaks in late January through early March. Probability of contact decreases rapidly in early spring and is lowest during late May and early June, corresponding to parturition and rearing of fawns. Contact probability remains low until fall when it increases in association with rut in November and December. The basic structure of the spatial extent of first-order direct contacts is described as the cumulative probability of contact and reaches 90% at 7,400 m and 99% at 10,900 m. Corresponding extents for indirect contact probabilities occur at 10,250 m and 48,750 m, respectively. We further refine our estimates of areas with the greatest potential for direct contact to occur, or that are at a high risk for contamination by prions through the use of resource selection functions to characterize the behavioral choices deer make in using different landscape attributes. Rendering a map of the statistical distribution of the risk of disease spread suggests that allocation of resources to control the spread of the disease could be much more tightly focused than the 16 km (10-mile) radius containment area. If managers are comfortable accepting a 90% probability of containing first-order direct contact, a radius of 7.5 km (4.7 miles) could be used in central New York. This reduces the area from approximately 800 km2 (300 square miles) to approximately 170 km2 (66 mi2). Targeting of specific land-cover types within that containment area can further reduce the area of primary focus