Nohra E. Mateus-Pinilla

White-tailed deer (Odocoileus virginianus; WTD) are an abundant species in the United States of America (U.S.) that live closely with humans and carry zoonotic pathogens. In 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spilled over from humans into WTD and spread throughout the population. In many areas of the U.S., chronic wasting disease (CWD), a slow-progressing and fatal prion disease, is endemic in WTD populations. WTD infected with CWD may have altered behavior or physiological conditions that pre-dispose them to infection with other pathogens. This study aimed to examine the co-occurrence patterns of CWD and SARS-CoV-2. Individual WTD were tested for both SARS-CoV-2 and CWD during two fall/winter seasons (2021–2022 and 2022–2023) across the CWD-endemic area of Illinois. We investigated the co-occurrence of the two diseases in individuals and spatially at the scale of management ‘sections’ to identify potential predictive factors. We did not find evidence that SARS-CoV-2 was more likely to occur in individual WTD that also tested positive for CWD. However, management sections with CWD detections predicted a 481% increase in the probability of SARS-CoV-2 detection, suggesting that the presence of CWD increases the chance of SARS-CoV-2 detection in the same area. We found also that occurrence of SARS-CoV-2 at the section level was predicted by different environmental factors than CWD, suggesting that their non-random co-occurrence was not driven by the same underlying mechanisms.

Chronic wasting disease (CWD) is an invariably fatal neurodegenerative disease of cervids detected in wild and captive herds in the United States, Canada, Norway, Sweden, and Finland since its disc...

Members of the family Cervidae, both wild and captive, are becoming increasingly affected by chronic wasting disease (CWD), a prion disease with high transmissibility and a 100% fatality rate [1–3]...

Chronic wasting disease (CWD) is a highly transmissible spongiform encephalopathy impacting cervids. Variations in the prion protein gene ( PRNP ), encoding the prion protein (PrP), influence disease progression and susceptibility. Protein sequence is a key determinant of PrP strains and their capacity for interspecies transmission. Sequencing PRNP in white-tailed deer has revealed non-synonymous polymorphisms impacting disease—c.285A > C (Q95H) and c.286G > A (G96S). Previous PRNP amplification protocols misclassified homozygous and heterozygous deer due to allelic dropout by a widely used forward primer. We resequenced 586 deer previously classified as homozygous using a redesigned primer (designated Ov- PRNP -F2) and found 128 heterozygotes. Subsequently, we sequenced additional CWD-positive and CWD-negative deer using Ov- PRNP -F2 to correct for dropout and then estimated PrP variant susceptibility and CWD risk using 778 CWD-positive and 3,070 CWD-negative deer from 22 Illinois counties, the largest PRNP sequence dataset to date. Animals encoding PrP variant combination C (96S) and F (95H) were the least susceptible to CWD (OR = 0.03, p < 0.001) compared to deer encoding two copies of PrP variant A 95Q;96G. A novel finding is that deer encoding a single copy of PrP 95H were less susceptible to CWD compared to those with a single copy of PrP 96S (OR = 0.40, p < 0.001). The results support using genotyping methods to map susceptibility to CWD across the landscape, focusing on PrP variant frequencies to improve CWD epidemiological risk models.

Chronic wasting disease (CWD) is a fatal neurodegenerative prion disease of cervids that can be transmitted through direct physical contact, indirect contact with a contaminated environment, or vertical transmission. CWD is characterized by a long incubation period followed by symptoms like loss of appetite resulting from the destruction of brain tissue. While the consequences for infected animals are clear, a previous study from our laboratory showing lower body weights in the foetuses of CWD-positive female deer suggests those consequences may be intergenerational. In this study, we addressed the impact of maternal CWD infection on foetal head development (as a proxy for brain growth) in wild white-tailed deer using data from CWD management efforts in northern Illinois, U.S.A. Multivariate, multilevel, Bayesian Gamma regression found that maternal CWD infection reduced foetal head nose-occipital length and crown-jaw circumference by 6.76% and frontal-occipital length by 11.31%. These findings suggest impeded brain development in the offspring of CWD-infected female deer, which could reduce fawns' survival and success after birth and lead to a decline in population fitness over time. This study is the first to demonstrate the detrimental effects of a prion disease on foetal brain development in any animal species regardless of whether vertical transmission has occurred.

White-tailed deer (Odocoileus virginianus) are a cervid species native to the Americas with ecological, social, and economic significance. Managers must consider several factors when working to maintain the health and sustainability of these wild herds, including reproduction, particularly pregnancy and recruitment rates. White-tailed deer have a variable reproductive capacity, with age, health, and habitat influencing this variability. However, it is unknown whether chronic wasting disease (CWD) impacts reproduction and, more specifically, if CWD infection alters a female deer’s probability of pregnancy. Our study addressed this question using data from 9783 female deer culled in northern Illinois between 2003 and 2023 as part of the Illinois Department of Natural Resources’ ongoing CWD management program. Multilevel Bayesian logistic regression was employed to quantify the relationship between pregnancy probability and covariates like maternal age, deer population density, and date of culling. Maternal infection with CWD was found to have no significant effect on pregnancy probability, raising concerns that the equal ability of infected and non-infected females to reproduce could make breeding, which inherently involves close physical contact, an important source of disease transmission between males and females and females and their fawns. The results also identified that female fawns (<1 year old) are sensitive to county-level deer land cover utility (LCU) and deer population density, and that there was no significant difference in how yearlings (1–2 years old) and adult (2+ years old) responded to these variables.

Chronic wasting disease (CWD) is a fatal, neurodegenerative disease of cervids, and its management heavily relies on diagnostic testing. Test results are commonly used to calculate 'apparent prevalence' (AP) - the percent of animals tested for CWD (CWD tests) with CWD-positive test results (CWD cases) - but this obscures how tests and cases individually contribute to this statistic. This is most relevant when CWD testing is limited because when few animals are tested, detection of even a single infected deer can result in a high AP that poorly reflects reality. We hypothesized that when CWD testing is limited, AP is negatively driven by testing - rather than cases - with more tests corresponding to lower APs. Graphed CWD surveillance data from townships in Illinois and Wisconsin, USA, indicate that CWD AP values ≥50% were only observed when <23 deer were tested. We used Bayesian multilevel zero-inflated Beta regression to model AP as a function of CWD tests, CWD cases and nonlinear transformations of these two terms separately for each state. The best-fit models of both identified a statistically significant negative relationship between AP and testing numbers that was modified by a positive nonlinear test covariate. This means adding tests when testing is low can have a big impact on decreasing the AP, but this relationship weakens as testing increases. We urge treating apparent prevalences ≥50% with caution and emphasize the importance of increasing the test results when initial surveillance has yielded <23 tests.