Wildlife Disease I

Contributed Oral Presentations

SESSION NUMBER: 23

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.

 

Following the Blood Trail: Identifying Bloodmeal Sources of Black-Legged Ticks Utilizing Next-Generation Sequencing
Lucas Price; John Edwards; Sheldon Owen; Raymond Rainbolt; Amy Welsh
On Fort Drum Military Installation, in northern New York, approximately 35% of black-legged ticks (Ixodes scapularis) are infected with Borrelia burgdorferi, the etiological agent responsible for Lyme disease. Due to this disease concern, recent research on site has sought to identify tick blood meals and wildlife reservoirs of Lyme disease. Small mammal trapping over the past several years has indicated a low abundance of Peromyscus sp., one of the primary reservoirs of Lyme disease in the Northeast, leading us to question which species are reservoirs of Lyme disease on Fort Drum. Our goal is to use genetic analysis of blood meals within black-legged ticks to identify successful blood meal sources. During 2018 and 2019, feeding ticks were collected from white-tailed deer (Odocoileus virginianus), Peromyscus sp., eastern chipmunk (Tamias striatus), American red squirrel (Tamiasciurus hudsonicus), and eastern gray squirrel (Sciurus carolinensis). We extracted DNA from a subsample of 20 black-legged ticks, representative of bloodmeals from all taxa mentioned above, using the Qiagen DNeasy Blood and Tissue kit, and the 12SV5 primer set was used to amplify target DNA. The 12SV5 primers amplify a region of mitochondrial DNA from all vertebrates and are commonly used in metabarcoding. Samples were individually indexed, and then all samples were pooled together and analyzed using Next-Generation Sequencing on the MiSeq Illumina system. We correctly identified all 20 tick samples to the known blood meal sources. With the success seen on known blood meal sources, we are currently applying this technique to questing ticks. Once we successfully identify blood meal sources of questing ticks, we will be able to test the same ticks for Borrelia burgdorferi. This will identify bloodmeal sources and indicate competent wildlife reservoirs of Lyme Disease on Fort Drum Military Installation without the bias and extensive field work of targeted wildlife trapping.
The Role of Climate Change in Creating Thermal Mismatches: Differential Species Response in Amphibian Host, Skin Microbe, and Disease Relationships
Courtney Hendrickson; Andrew Blaustein; Tiffany Garcia
This project explores the impact of thermal mismatches on the host-microbiome-disease triangle in the Northwest region. Climate change has been implicated in the acceleration of emerging infectious diseases. The pandemic amphibian chytrid fungus, caused by the fungal pathogen Batrachochytrium dendrobatids (Bd), infects the skin of amphibian hosts and leads to death in susceptible species. The thermal mismatch hypothesis states that deviations from historical temperature regimes will often favor parasites over hosts (i.e., thermal mismatches). Studies have confirmed that amphibian species with narrow thermal preferences, such as species inhabiting higher elevations, experience higher Bd prevalence following thermal regime shifts. Bacteria harbored on amphibian skin can serve as barriers against Bd. The short generation times of bacterial species can rapidly respond to climate variation, potentially providing fitness advantages for the host. Conversely, increased temperature can also cause a shift from mutualistic to pathogen-dominated microbiomes. We sampled for amphibians at forty lentic sites across an elevational gradient in Mount Rainier National Park (MORA). MORA is an ideal study location as it encompasses a wide elevational breadth, contains Bd positive and negative sites, and has relatively high levels of amphibian biodiversity. We targeted seven species with varying elevational ranges. Environmental data was recorded at each site and skin and buccal swabs were taken to quantify Bd loads, characterize skin-microbiome community, and quantify salivary glucocorticoid (stress) levels. We generated a microclimatic map overlaid with species abundance data. We hypothesize that individuals on the edge of their thermal range will experience higher Bd loads, increased microbial diversity and higher glucocorticoid levels. Information generated by this study will be critical for monitoring potential climate-driven disease outbreaks as well as current and future vulnerability of Northwest amphibian populations.
Rabies Virus Exposure in the Small Indian Mongoose Across Puerto Rico
Amt T. Gilbert; Are Berentsen; Mel J. Rivera-Rodriguez; Fabiola B. Torres-Toledo; Shylo R. Johnson; Christine K. Ellis; Chad K. Wickham; Richard B. Chipman
The small Indian mongoose (Herpestes auropunctatus) is a rabies reservoir on several islands in the Caribbean, including Puerto Rico. Oral rabies vaccination (ORV) has been proposed as a tool to control rabies virus circulation in mongoose populations. The presence of rabies virus neutralizing antibodies (RVNA) is often used as evidence of natural exposure, or an abortive infection, among wildlife. We conducted a sero-survey of mongooses on 10 properties across Puerto Rico. Distance between six non-adjacent properties ranged from five to 150 km. We captured and anesthetized mongooses to collect whole blood samples. We centrifuged blood to separate serum aliquots, which were frozen until analysis. We evaluated sera for RVNA by the Rapid Fluorescent Foci Inhibition Test (RFFIT) and titers > 0.1 IU/mL were considered positive for exposure to rabies virus. We collected 504 sera from unique mongooses across all properties during 2011-2019. A total of 110 samples (21.8%; 95% CI: 18.3 – 25.5%) were RVNA positive. Seroprevalence among properties ranged from 0.0 – 33.3%, although sample sizes were variable among properties. Our results support previous reports of a notable proportion of mongooses with evidence of natural exposure to rabies virus on Puerto Rico. Background seroprevalence must be taken into consideration when developing an ORV program for this species on Puerto Rico, especially for evaluation of management actions.
A Spatio-Temporal Integrated Population Model to Forecast Population Impacts of Heterogeneous Disease Dynamics
Alison C. Ketz; Daniel J. Storm; Daniel P. Walsh
Transmission dynamics, geographic spread, infection patterns, genetics and movements of hosts, and pathogen variation are processes that determine the impact of diseases on host populations. These processes operate on multiple scales across space and time, further complicating population effects. This complexity necessitates a flexible modeling approach that can structurally incorporate these ecological and biological processes. We have developed a spatiotemporal integrated population model (IPM) that assimilates disease dynamics within a host population model. We use our approach to examine impacts of chronic wasting disease (CWD), a contagious prion disease that affects cervids and exhibits intricate epizootic patterns. Our model incorporates data from numerous sources, including age-at-harvest, cross-sectional surveillance, GPS-collar locations of adults, VHF telemetry locations of juveniles, aerial surveys, pregnancy rates, and camera trap data, to assess the population impacts of CWD on white-tailed deer (Odocoileus virginianus) in the CWD-endemic region of south-central Wisconsin, USA. Previous studies indicate precipitous declines of CWD-affected cervid populations in the Rocky Mountains, but due to strikingly different environmental, behavioral, demographic, and density patterns, assessment for the midwestern USA is needed. IPMs frequently use mark-recapture data to obtain survival and disease rates, however, we use a time-to-event, age-period survival sub-model that includes infection status of marked individuals that can vary over time and across ages of individuals in the host population. We use the IPM to forecast population trends under a variety of management actions, that are likely to influence population trajectories over time.
Assessing Disease Risks Related to Re-Introduction of Wolves to Isle Royale National Park
Michelle Verant; Tiffany Wolf; Seth Moore; Treana Mayer; Mark Romanski
Evaluating disease risks when translocating wildlife is an important aspect of project planning to account for potential unintended consequences for species conservation, wildlife health and human health. Frameworks for disease risk analysis have been developed, but examples of how these tools can be integrated into planning for wildlife translocation projects are limited. We included a disease risk analysis in planning for re-introduction of gray wolves (Canis lupus) to Isle Royale National Park, a project that was initiated in 2018 to restore predation, a key ecosystem community dynamic. We used the IUCN/OIE Guidelines for Disease Risk Analysis (DRA) to qualitatively assess and prioritize disease risks for wildlife and human health associated with capture and translocation of wolves. This process included a comprehensive knowledge review and input from project personnel with diverse expertise and experience. Outcomes of the DRA were used to determine mitigation measures including: 1) criteria for selection of wolves for translocation, 2) disease surveillance at time of capture, 3) targeted prophylactic treatments and 4) biosecurity measures to prevent disease transmission. Results from disease surveillance and post-release monitoring are being used to reassess and refine the DRA. This iterative process allows us to adapt in response to new information or changing situations throughout the duration of the project.

 

Virtual
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