The impact of maternal infection with chronic wasting disease on fetal characteristics in wild white-tailed deer (Odocoileus virginianus) in Illinois, USA

Abstract

Chronic wasting disease (CWD) is a fatal neurodegenerative disease of cervids caused by a misfolded and infectious protein, called a prion. Infection with CWD is characterized by an asymptomatic period, followed by a decline that inevitably leads to death. The disease is transmitted mainly through direct contact between infected and uninfected animals, but vertical transmission has been documented in muntjac deer ( Muntiacus reevesi ), along with the presence of infectious prions in the reproductive tissues of elk ( Cervus canadensis ) and white-tailed deer ( Odocoileus virginianus ). Therefore, questions have been raised about the effects of CWD on the health and characteristics of the offspring gestated by infected animals, and about how vertical transmission may complicate disease management efforts and drive reduction of herd fitness. To begin finding quantitative answers to these questions, this study used multilevel Bayesian linear regression to model the influence of maternal infection with CWD, along with several other environmental and biological variables, on fetal weight, sex, and length using data collected on white-tailed deer as part of the CWD management program in Illinois for the time period between fiscal years 2003 and 2020. The regression analyses found no statistically significant relationship between maternal CWD status and fetal length or the fraction of males in a litter but did find a significant relationship between maternal infection and fetal weight. Fetuses of CWD positive deer weighed 1% less than fetuses from deer in which CWD was not detected. Given that 88% of the fetuses in this data were in the second trimester of gestation, the impact of CWD on fetuses through the entire course of gestation remains to be evaluated. • Fetal weights in the second trimester were 1% lower in CWD positive female deer • Fetal length showed no significant relationship with maternal CWD infection • Fetal sex ratios were 1:1 regardless of maternal CWD infection status