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Behind the Science: Researching the so-called “zombie deer disease”

***Dr. Perrin-Stowe was awarded the Stephen J. O’Brien Award for best student paper published in the Journal of Heredity***



About the Author: Tolulope Perrin-Stowe is a graduate student within the Roca laboratory group at the University of Illinois at Urbana-Champaign. She passed her doctoral defense in December 2020 and will be awarded her doctoral degree in May 2021. She works on the conservation genetics of endangered and threatened species and is passionate about evolutionary history and community-based conservation.




The journey to producing my paper on the genetics of chronic wasting disease (CWD) vulnerability in cervids started with preparations to present research at the 54TH meeting of the Illinois Chapter of the Wildlife Society in April 2018. This conference is focused on sharing research that helps to protect and manage wildlife populations. I was presenting a poster on African elephant phylogeography, which was the project I was working on at that point in my graduate studies within the Roca laboratory. Meanwhile, Dr. Yasuko Ishida, a research scientist who is in the same group was presenting the findings from a new collaboration. The details were unknown to me at the time but her work would be incorporated into a paper that provided a strong foundation for my own study. This study, led by Dr. Adam Brandt who was a previous PhD student in the Roca laboratory group, assessed 2,433 white-tailed deer from Wisconsin and Illinois for polymorphisms that have been previously associated with reduced vulnerability to CWD. Deer with PRNP (prion gene) haplotypes that encoded either the amino acid histidine at codon 95 (instead of the wildtype glutamine) or the amino acid serine at codon 96 (instead of the wildtype glycine) were found in significantly higher proportions in CWD-negative deer than in CWD-positive deer (Brandt et al., 2018).

During this time in spring of 2018, I was first introduced to detailed knowledge about prion diseases. My initial association of prion diseases was with “mad cow disease” (bovine spongiform encephalopathy) and kuru, which is a prion disease historically contracted by the Fore people of Papua New Guinea who practiced endocannibalistic rituals (consumption of deceased community members for religious and spiritual purposes) until the mid-1900s (Mead et al., 2003). Therefore, I was surprised to hear that a widespread prion disease was affecting populations of several cervid species in North America and had even been detected in several countries in Eurasia (Rivera et al., 2019). I had not heard about the disease in any of my graduate courses and had not come across it in the news. While it seemed that hunters and wildlife managers were well aware of CWD and the risk it presented, the disease was not widely discussed in other circles. Learning about the persistence of prions in the environment, the mechanisms of prion propagation, and the risk to wildlife populations further sparked my interest in the disease.

In early 2019, while the term “zombie deer disease” was making the rounds in the news cycle, I was given the opportunity to sequence PRNP in stored samples of the endangered Florida Key deer (a white-tailed deer subspecies). At first, my study only consisted of around 20 Florida Key deer but I received more Florida Key deer samples and Columbian white-tailed deer (another endangered white-tailed deer subspecies) samples in late 2019 and was able to add them to the study. As the pandemic was starting, we were finalizing the manuscript to submit to the Journal of Heredity. Since submitting the Florida Key deer and Columbian white-tailed deer PRNP alleles study to the journal (Perrin-Stowe et al., 2020), my coauthors and I have been working on similar studies in endangered cervids that are held in accredited zoos and conservation centers in North America. These facilities are concerned about the risk that CWD presents to their cervid populations and we have been working to address that concern for a couple of endangered species. It has been a challenge conducting these studies during the pandemic but with a supportive team, I was able to complete the sequencing and analysis and now we plan to publish these subsequent papers this year to provide valuable information that can aid in managing captive cervid populations for CWD.

Working on the genetics of wildlife disease and population management combines my own interest in evolutionary history and genetic variation with research that can be directly applied to the conservation of threatened and endangered species. In light of Covid-19 and its hypothesized origins in wildlife populations (Andersen et al., 2020), it has become clear that studying diseases in wildlife is a valuable research path. I am grateful for the opportunity to study such a unique disease and to present research that can be used to help protect wildlife.


Andersen, K. G., Rambaut, A., Lipkin, W. I., Holmes, E. C., & Garry, R. F. (2020). The proximal origin of SARS-CoV-2. Nature Medicine, 26(4), 450-452.

Brandt, A. L., Green, M. L., Ishida, Y., Roca, A. L., Novakofski, J., & Mateus-Pinilla, N. E. (2018). Influence of the geographic distribution of prion protein gene sequence variation on patterns of chronic wasting disease spread in white-tailed deer (Odocoileus virginianus). Prion, 12(3-4), 204-215.

Mead, S., Stumpf, M. P. H., Whitfield, J., Beck, J. A., Poulter, M., Campbell, T., Uphill, J. B., Goldstein, D., Alpers, M., Fisher, E. M. C., & Collinge, J. (2003). Balancing selection at the prion protein gene consistent with prehistoric kurulike epidemics. Science, 300(5619), 640-643.

Perrin-Stowe, T. I. N., Ishida, Y., Terrill, E. E., Hamlin, B. C., Penfold, L., Cusack, L. M., Novakofski, J., Mateus-Pinilla, N. E., & Roca, A. L. (2020). Prion protein gene (PRNP) sequences suggest differing vulnerability to chronic wasting disease for Florida Key deer (Odocoileus virginianus clavium) and Columbian white-tailed deer (O. v. leucurus). Journal of Heredity, 11(6), 564–572.

Rivera, N. A., Brandt, A. L., Novakofski, J. E., & Mateus-Pinilla, N. E. (2019). Chronic wasting disease in cervids: prevalence, impact and management strategies. Veterinary medicine (Auckland, N.Z.), 10, 123-139.

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