F. Bravo-Risi R. Morales D. P. Walsh D. J. Storm J. A. Pedersen Wendy Christine Turner S. S. Lichtenbergh H. N. Inzalaco 2023 <p><span>Chronic wasting disease (CWD) is a fatal neurodegenerative disease caused by infectious prions (PrP</span>^CWD<span>) affecting cervids. Circulating PrP</span>^CWD<span>&nbsp;in blood may pose a risk for indirect transmission by way of hematophagous ectoparasites acting as mechanical vectors. Cervids can carry high tick infestations and exhibit allogrooming, a common tick defense strategy between conspecifics. Ingestion of ticks during allogrooming may expose naïve animals to CWD, if ticks harbor PrP</span>^CWD<span>. This study investigates whether ticks can harbor transmission-relevant quantities of PrP</span>^CWD<span>&nbsp;by combining experimental tick feeding trials and evaluation of ticks from free-ranging white-tailed deer (</span><i>Odocoileus virginianus</i><span>). Using the real-time quaking-induced conversion (RT-QuIC) assay, we show that black-legged ticks (</span><i>Ixodes scapularis</i><span>) fed PrP</span>^CWD<span>-spiked blood using artificial membranes ingest and excrete PrP</span>^CWD<span>. Combining results of RT-QuIC and protein misfolding cyclic amplification, we detected seeding activity from 6 of 15 (40%) pooled tick samples collected from wild CWD-infected white-tailed deer. Seeding activities in ticks were analogous to 10–1000&nbsp;ng of CWD-positive retropharyngeal lymph node collected from deer upon which they were feeding. Estimates revealed a median infectious dose range of 0.3–42.4 per tick, suggesting that ticks can take up transmission-relevant amounts of PrP</span>^CWD<span>&nbsp;and may pose a CWD risk to cervids.</span></p> application/pdf 10.1038/s41598-023-34308-3 en Springer Nature Ticks harbor and excrete chronic wasting disease prions article