Chronic Wasting Disease: Transmission by Ticks

Scientific Reports (Inzalaco, HN; et al.) published 5.15.23 “Ticks harbor and excrete chronic wasting disease prions.” In this study, researchers investigated the role of ticks in the transmission of chronic wasting disease (CWD) in members of the deer family (cervids). CWD is a neurodegenerative disease caused by infectious prions (misfolded proteins) that result in a slow but progressive and fatal outcome for both wild and domestic cervids that are exposed. Both direct and indirect routes of exposure and transmission are found to contribute to increase of prevalence and geographic spread of CWD.

Cervids can carry high numbers of ticks; and through grooming each other, may ingest high quantities of prion infected ticks. This behavior of ingesting ticks is shown to be a potential cause of indirect transmission of CWD  between individuals. 

This study found that infected blacklegged ticks can carry “transmission‑relevant” prions; and that when fed in sufficient quantities to white tailed deer, are responsible for indirect CWD transmission in individuals. A median infectious dose range of 0.3–42.4 per tick suggests that ticks can take up “transmission‑relevant” amounts of prions capable of transmitting CWD among cervids

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