Comparison of Chronic Wasting Disease Detection Methods and Procedures: implications for free-ranging white-tailed deer (Odocoileus virginianus) surveillance and management
Throughout North America, chronic wasting disease (CWD) has emerged as perhaps the greatest threat to wild cervid populations, including white-tailed deer (Odocoileus virginianus). White-tailed deer are the most sought after big game species across North America with populations of various subspecies in nearly all Canadian provinces, the contiguous USA, and Mexico. Documented CWD cases have dramatically increased across the white-tailed deer range since the mid-1990s, including in Minnesota. CWD surveillance in free-ranging white-tailed deer and other cervid populations mainly depends upon immunodetection methods (e.g., immunohistochemistry [IHC] and enzyme-linked immunosorbent assay [ELISA]) on medial retropharyngeal lymph nodes and obex. More recent technologies centered on prion protein amplification methods of detection have shown promise as more sensitive and rapid CWD diagnostic tools. Here, we used blinded samples to test the efficacy of real time quaking-induced conversion (RT-QuIC) in comparison to ELISA and IHC for screening tissues, blood, and feces collected in 2019 from white-tailed deer in southeastern Minnesota, where CWD has been routinely detected since 2016. Our results support previous findings that RT-QuIC is a more sensitive tool for CWD detection than current antibody-based methods. Additionally, a CWD testing protocol that includes multiple lymphoid tissues (medial retropharyngeal lymph node, parotid lymph node, and palatine tonsil) per animal may effectively identify a greater number of CWD detections in a white-tailed deer population than a single sample type (i.e., medial retropharyngeal lymph nodes). These results reveal that the variability of CWD pathogenesis, sampling protocol, and testing platform must be considered for the effective detection and management of CWD throughout North America.