Shedding and stability of CWD prion seeding activity in cervid feces.

CWD is an emergent prion disease that now affects cervid species on three continents. CWD is efficiently spread in wild and captive populations, likely through both direct animal contact and environmental contamination. Here, by longitudinally assaying in feces of CWD-exposed white-tailed deer by RT-QuIC, we demonstrate fecal shedding of prion seeding activity months before onset of clinical symptoms and continuing throughout the disease course. We also examine the impact of simulated environmental conditions such as repeated freeze-thaw cycles and desiccation on fecal prion seeding activity. We found that while multiple (n = 7) freeze-thaw cycles substantially decreased fecal seeding activity, desiccation had little to no effect on seeding activity. Finally, we examined whether RT-QuIC testing of landscape fecal deposits could distinguish two premises with substantial known CWD prevalence from one in which no CWD-infected animals had been detected. In the above pilot study, this distinction was possible. We conclude that fecal shedding of CWD prions occurs over much of the disease course, that environmental factors influence prion seeding activity, and that it is feasible to detect fecal prion contamination using RT-QuIC.