Evaluation of a wild white-tailed deer population management program for controlling chronic wasting disease in Illinois, 2003–2008

AbstractWe evaluated population management programs for controlling chronic wasting disease (CWD) in wild white-tailed deer in Illinois between November 2002 and March 2008. The intervention consisted of measures of deer removal from three deer population control programs: Illinois Department of Natural Resources culling, deer population control permits and nuisance deer removal permits. We included in the analysis a total of 14,650 white-tailed deer CWD test results. These data also included location and demographic data collected from both deer harvested in the interventions as well as deer from hunter harvests and deer vehicle collisions. We quantified intervention pressures as the number of years of intervention, the total number of deer removed and the average number of deer removed per year. We accounted for temporal and spatial variations of intervention by using mixed logistic regression to model the association between intervention pressures and CWD prevalence change. The results showed that deer population management intervention as practiced in Illinois during the study period was negatively associated with CWD prevalence and the strength of association varied depending on age of deer and the measure of intervention pressure. The population management programs showed a more consistent association with reduced CWD prevalence in fawn and yearling white-tailed deer than in adult deer. Our results also suggested that frequent and continuing intervention events with at least moderate intensity of culling were needed to reduce CWD prevalence. A longer study period, however, is needed to make a more definite conclusion about the effectiveness of similar population management programs for controlling CWD in wild white-tailed deer

Chronic Wasting Disease In Cervids: Prevalence, Impact And Management Strategies

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that affects members of the cervidae family. The infectious agent is a misfolded isoform (PrPSC) of the host prion protein (PrPC). The replication of PrPSC initiates a cascade of developmental changes that spread from cell to cell, individual to individual, and that for some TSEs, has crossed the species barrier. CWD can be transmitted horizontally and vertically, and it is the only TSE that affects free-ranging wildlife. While other TSEs are under control and even declining, infection rates of CWD continue to grow and the disease distribution continues to expand in North America and around the world. Since the first reported case in 1967, CWD has spread infecting captive and free-ranging cervids in 26 states in the US, 3 Canadian provinces, 3 European countries and has been found in captive cervids in South Korea. CWD causes considerable ecologic, economic and sociologic impact, as this is a 100% fatal highly contagious infectious disease, with no treatment or cure available. Because some TSEs have crossed the species barrier, the zoonotic potential of CWD is a concern for human health and continues to be investigated. Here we review the characteristics of the CWD prion protein, mechanisms of transmission and the role of genetics. We discuss the characteristics that contribute to prevalence and distribution. We also discuss the impact of CWD and review the management strategies that have been used to prevent and control the spread of CWD.https://digitalcommons.snc.edu/faculty_staff_works/1033/thumbnail.jp

Prion protein gene sequence and chronic wasting disease susceptibility in white-tailed deer (Odocoileus virginianus)

The sequence of the prion protein gene (PRNP) affects susceptibility to spongiform encephalopathies, or prion diseases in many species. In white-tailed deer, both coding and non-coding single nucleotide polymorphisms have been identified in this gene that correlate to chronic wasting disease (CWD) susceptibility. Previous studies examined individual nucleotide or amino acid mutations; here we examine all nucleotide polymorphisms and their combined effects on CWD. A 626 bp region of PRNP was examined from 703 free-ranging white-tailed deer. Deer were sampled between 2002 and 2010 by hunter harvest or government culling in Illinois and Wisconsin. Fourteen variable nucleotide positions were identified (4 new and 10 previously reported). We identified 68 diplotypes comprised of 24 predicted haplotypes, with the most common diplotype occurring in 123 individuals. Diplotypes that were found exclusively among positive or negative animals were rare, each occurring in less than 1% of the deer studied. Only one haplotype (C, odds ratio 0.240) and 2 diplotypes (AC and BC, odds ratios of 0.161 and 0.108 respectively) has significant associations with CWD resistance. Each contains mutations (one synonymous nucleotide 555C/T and one nonsynonymous nucleotide 286G/A) at positions reported to be significantly associated with reduced CWD susceptibility. Results suggest that deer populations with higher frequencies of haplotype C or diplotypes AC and BC might have a reduced risk for CWD infection – while populations with lower frequencies may have higher risk for infection. Understanding the genetic basis of CWD has improved our ability to assess herd susceptibility and direct management efforts within CWD infected areas.https://digitalcommons.snc.edu/faculty_staff_works/1029/thumbnail.jp

Evaluation of the Effectiveness of a Feline Toxoplasma Vaccine in Reducing the Exposure of Swine to Toxoplasma Gondii

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2000.The second study used a deterministic dynamic computer simulation model of the transmission of T. gondii in the swine farm ecosystem in a factorial experimental design to test the following hypotheses. T. gondii infection in finishing pigs decreases with (1) vaccination of susceptible cats, (2) increased cat capture rate (for vaccination), (3) decreased number of cats, (4) decreased T. gondii prevalence in cats, and (5) decreased oocyst survival time. Simulations were run for 10 years, with a weekly interval. Elimination of T. gondii in finishing pigs increased with a decrease in oocysts survival and a decrease in the number of cats in the farm. T. gondii prevalence in finishing pigs decreased with a decrease in the number of cats, a decrease in oocyst survival time, vaccinating and using an optimized vaccination schedule. Initial T. gondii prevalence in cats had no effect on outcome. Vaccination had less impact in decreasing T. gondii infection in finishing pigs than a decrease in the number of farm cats.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Evaluation of the Effectiveness of a Feline Toxoplasma Vaccine in Reducing the Exposure of Swine to Toxoplasma Gondii

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2000.The second study used a deterministic dynamic computer simulation model of the transmission of T. gondii in the swine farm ecosystem in a factorial experimental design to test the following hypotheses. T. gondii infection in finishing pigs decreases with (1) vaccination of susceptible cats, (2) increased cat capture rate (for vaccination), (3) decreased number of cats, (4) decreased T. gondii prevalence in cats, and (5) decreased oocyst survival time. Simulations were run for 10 years, with a weekly interval. Elimination of T. gondii in finishing pigs increased with a decrease in oocysts survival and a decrease in the number of cats in the farm. T. gondii prevalence in finishing pigs decreased with a decrease in the number of cats, a decrease in oocyst survival time, vaccinating and using an optimized vaccination schedule. Initial T. gondii prevalence in cats had no effect on outcome. Vaccination had less impact in decreasing T. gondii infection in finishing pigs than a decrease in the number of farm cats.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Genetic assignment tests reveal dispersal of white-tailed deer: implications for chronic wasting disease

Investigating sources of infection for new disease cases is critical to effective disease management. Chronic wasting disease (CWD) was first detected among white-tailed deer (Odocoileus virginianus) in Illinois in 2002. Although CWD was focused in northern Illinois, 4 infected deer were sampled in 2011 from locations greater than 100 km south of the disease focus. We used assignment tests (Geneclass2 and Oncor) to determine a likely genetic source location for infected deer. Our baseline data set consisted of 310 deer sampled from 10 locations. From the baseline data set, we determined the most likely genetic source location of 15 CWD-positive and 15 CWD-negative deer. A total of 17–20% back-assigned to their sample location as their most likely genetic source location and the remainder of the animals cross-assigned to another location. The average distance between locations was 41.4 km for Geneclass2 and 43.4 km for Oncor (range 0.0–90.8 km). Distances between source and sampling locations were similar for positive and negative animals. Distances for males were greater than those for females using Oncor, but there was no difference in distance based on age. Because there are few barriers to gene flow for white-tailed deer, managers should reduce movement of deer in CWD-infected areas in an effort to reduce direct and indirect transmission of CWD.Ope

Influence of landscape factors and management decisions on spatial and temporal patterns of the transmission of chronic wasting disease in white-tailed deer

Abstract. Chronic wasting disease (CWD) has been reported in white-tailed deer at the border of the US states of Illinois and Wisconsin since 2002. Transmission of infectious prions between animals and from the environment has resulted in spatial and temporal structure observable in the spatio-temporal patterns of reported cases. Case locations of 382 positive cases from 28,954 deer tested between 2002 and 2009 provided insight into the potential risk factors and landscape features associated with transmission using a combination of clustering, generalised linear modelling and descriptive evaluations of a risk map of predicted cases of CWD. A species distribution map of white-tailed deer developed using MaxEnt provided an estimate of deer locations. We found that deer probability increased in areas with larger forests and less urban and agricultural lands. Spatial clustering analysis revealed a core area of persistent CWD transmission in the northern part of the region. The regression model indicated that larger and more compact forests were associated with higher risk for CWD. High risk areas also had soils with less clay and more sand than other parts of the region. The transmission potential was higher where landscape features indicated the potential for higher deer concentrations. The inclusion of spatial lag variables improved the model. Of the 102 cases reported in the study area in the two years following the study period, 89 (87%) of those were in the 32% of the study area with the highest 50% of predicted risk of cases

Data from: Survey of haemosporidian parasites in resident and migrant game birds of Illinois

Haemosporidian parasites are globally distributed in avian species, capable of leading to decreased reproductive success, weakness and mortality. Haemosporidian parasites that affect reproduction and population growth are of interest to bird conservation groups and to organizations concerned with the health and immunological status of avian populations. Haemosporidian infection data are not always available for some avian species in specific regions yet. These data provides the starting points to evaluate geographical and temporal changes in the patterns of infection and prevalence across populations. We examined haemoparasite infections in four game bird species commonly hunted in Illinois. Prevalence, mean intensity, median intensity and mean abundance of haemosporidians were calculated, and the relation of these infection measures associated with age and sex of the avian hosts were evaluated. Game species sampled (n = 237) included migrants such as mourning doves (Zenaida macroura), wood ducks (Aix sponsa) and Canada geese (Branta canadensis), as well as resident birds such as wild turkeys (Meleagris gallopavo). Only Haemoproteus, Plasmodium, and Leucocytozoon species were identified. Haemoproteus was the most prevalent haemosporidian (46/237), followed by Plasmodium (11/237). Furthermore, Haemoproteus was the most persistent haemosporidian, as it was the only parasite genera found in all four avian species. Co-infections were found in 55% of turkeys, but no significant correlations between the genera of haemosporidinan co-infections and a host species were found. Moreover, no significant differences in the proportion of infected individuals (prevalence) and haemosporidian quantities (levels of intensity and abundance) were related to biotic factors such as age and sex of the host. However, parasite aggregation (distribution of parasites among hosts) was affected by age, as adult turkeys and juvenile doves showed the highest aggregation index (Poulin’s index of discrepancy D) for Haemoproteus spp. This study reveals patterns of infection and parasite aggregations that vary widely among different game bird species and provides baseline data on avian haemosporidians that, to the best of our knowledge, is not currently available in the state of Illinois for these avian species. Finally, these patterns can be used for management of landscape or host species to support conservation efforts