Chronic Wasting Disease Surveillance

Chronic wasting disease (CWD) is a contagious, fatal disease of deer, elk, and moose for which there is no vaccine or known treatment. It is transmitted by direct animal-to-animal contact or, indirectly, through the environment. Deer, elk, and moose of Yellowstone National Park are at near-term risk for CWD infection because known infected deer are approximately 130 miles distant from the park, the disease has recently spread across Wyoming towards the park, and there are large populations of deer and elk that utilize park habitats. During 2004 and 2005, we collaborated with the Montana Department of Fish, Wildlife and Parks and the Biological Resources Management Division of the National Park Service to test tissue samples from 703 elk harvested adjacent to Yellowstone’s northwestern boundary. Most of these elk migrate into the park during summer. None of the tissue samples were positive for CWD. We have developed a plan to continue surveillance for CWD and, if necessary, implement disease management actions to minimize transmission risk factors and prevalence of CWD in deer and elk, while ensuring park resources and values are not harmed and minimizing human intervention to the extent feasible. Unlike other areas where CWD already occurs, Yellowstone supports an intact large predator complex. Wolves, in particular, are highly selective for elk throughout the year. If predators can detect CWD-infected animals before or soon after they begin shedding infectious agent, then selective predation could reduce CWD transmission rates and, in turn, the prevalence and spread of the disease.