The science behind the scent – An interdisciplinary approach to understanding how chronic wasting disease influences feces from white-tailed deer leading to discrimination of disease status by canines.

Chronic wasting disease (CWD) is an ever-expanding threat to both wild and captive cervids.  Management of the disease is compounded by its ability to spread directly and indirectly, be shed and persist in the environment, and cause the invariable fatal outcome of infected individuals.  Agencies are challenged to sample significant numbers of individuals to detect the disease, but these efforts are hampered by the costs, sample numbers, test turnaround times, and the fact that only post-mortem sampling is currently approved for testing.  Developing antemortem and landscape-scale detection methods could become a critical game changer in CWD diagnostics and management.  For this project we collaborate with agencies and departments across the University of Pennsylvania, to address this need by studying how CWD affects its host and leads to systemic changes in white-tailed deer, including changes in their fecal microbiome and associated volatile organic compound (VOC) profiles.  Our team discovered that CWD leads to significant changes in the fecal microbiome and VOC profiles, and that canines can discriminate between feces from CWD positive and negative animals. Changes to the microbiome and VOC profiles occurred gradually with disease progression but remained distinct enough for molecular detection and canine discrimination.  Interestingly, the VOC fingerprints and fecal microbiome changes differ significantly between captive and wild cervids, suggesting that factors such as diet and ecology may play additional roles in disease progression. The long-term goal of this collaborative project is to develop new, potentially rapid, antemortem or environmental diagnostics for CWD detection in the field.