Predicting chronic wasting disease in white-tailed deer at the county scale using machine learning.

Continued spread of chronic wasting disease (CWD) through wild cervid herds negatively impacts populations, erodes wildlife conservation, drains resource dollars, and challenges wildlife management agencies. Risk factors for CWD have been investigated at state scales, but a regional model to predict locations of new infections can guide increasingly efficient surveillance efforts. We predicted CWD incidence by county using CWD surveillance data depicting white-tailed deer (Odocoileus virginianus) in 16 eastern and midwestern US states. We predicted the binary outcome of CWD-status using four machine learning models, utilized five-fold cross-validation and grid search to pinpoint the best model, then compared model predictions against the subsequent year of surveillance data. Cross validation revealed that the Light Boosting Gradient model was the most reliable predictor given the regional data. The predictive model could be helpful for surveillance planning. Predictions of false positives emphasize areas that warrant targeted CWD surveillance because of similar conditions with counties known to harbor CWD. However, disagreements in positives and negatives between the CWD Prediction Web App predictions and the on-the-ground surveillance data one year later underscore the need for state wildlife agency professionals to use a layered modeling approach to ensure robust surveillance planning. The CWD Prediction Web App is at https://cwd-predict.streamlit.app/ .

PSEUDORABIES (AUJESZKY'S DISEASE) IS AN UNDERDIAGNOSED CAUSE OF DEATH IN THE FLORIDA PANTHER (PUMA CONCOLOR CORYI).

Feral swine (Sus scrofa), an important prey species for the endangered Florida panther (Puma concolor coryi), is the natural host for pseudorabies virus (PRV). Prior to this study, PRV had been detected in just three panthers. To determine the effect of PRV on the panther population, we prospectively necropsied 199 panthers and retrospectively reviewed necropsy and laboratory findings, reexamined histology, and tested archived tissues using real-time PCR from 46 undiagnosed panther mortalities. Seven additional infections (two prospective, five retrospective) were detected for a total of 10 confirmed panther mortalities due to PRV. To further evaluate the effect of PRV, we categorized radio-collared (n=168) and uncollared panther mortalities (n=367) sampled from 1981 to 2018 based on the likelihood of PRV infection as confirmed, probable, suspected, possible, or unlikely/negative. Of 168 radio-collared panthers necropsied, PRV was the cause of death for between eight (confirmed; 4.8%) and 32 (combined confirmed, probable, suspected, and possible categories; 19.0%) panthers. The number of radio-collared panther mortalities due to PRV was estimated to be 15 (95% empirical limits: 12-19), representing 8.9% (confidence interval: 4.6-13.2%) of mortalities. Gross necropsy findings in 10 confirmed cases were nonspecific. Microscopic changes included slight to mild perivascular cuffing and gliosis (primarily in the brain stem), lymphoplasmacytic meningoencephalitis (cerebral cortex), and intranuclear inclusion bodies (adrenal medulla). The PRV glycoprotein C gene sequences from three positive panthers grouped with the sequence from a Florida feral swine. Our findings indicate that PRV may be an important and underdiagnosed cause of death in Florida panthers.

Distribution and host associations of ixodid ticks collected from wildlife in Florida, USA.

A tick survey was conducted to document tick-host associations with Florida (USA) wildlife, and to determine the relative abundance and distribution of ixodid ticks throughout the state. The survey was conducted using collection kits distributed to licensed Florida hunters as well as the examination of archived specimens from ongoing state wildlife research programs. Collected tick samples were obtained from 66% of Florida counties and were collected from nine wildlife hosts, including black bear, bobcat, coyote, deer, gray fox, Florida panther, raccoon, swine, and wild turkey. In total, 4176 ticks were identified, of which 75% were Amblyomma americanum, 14% Ixodes scapularis, 8% A. maculatum, 3% Dermacentor variabilis, and < 1% were I. affinis and I. texanus. americanum, D. variabilis, and I. scapularis had the broadest host range, while A. maculatum, D. variabilis, and I. scapularis had the widest geographic distribution. While the survey data contribute to an understanding of tick-host associations in Florida, they also provide insight into the seasonal and geographic distribution of several important vector species in the southeastern USA.

Prevalence of Tick-Borne Pathogens in Host-Seeking Amblyomma americanum (Acari: Ixodidae) and Odocoileus virginianus (Artiodactyla: Cervidae) in Florida.

Amblyomma americanum (L.), the lone star tick, is an aggressive tick that is expanding its geographic range within the United States. This tick is the vector for the human and veterinary pathogens Ehrlichia chaffeensis and Ehrlichia ewingii and is associated with other microbes of unspecified pathogenicity including Rickettsia amblyommii, Panola Mountain Ehrlichia, and Borrelia lonestari In Florida, there has been sparse contemporary data on the prevalence of these organisms in host-seeking lone star ticks. To determine the prevalence of this tick and associated microbes in North Central Florida state parks, ∼1,500 lone star tick specimens were collected between 2010 and 2012 analyzed by polymerase chain reaction (PCR) sequencing. Additionally, 393 white-tailed deer, Odocoileus virginianus (Zimmerman), samples were analyzed for pathogen prevalence using molecular methods and serology. In lone star ticks, 14.6, 15.6, and 57.1% were positive for E. chaffeensis, E. ewingii, and Rickettsia spp. DNA, respectively. Panola Mountain Ehrlichia or B. lonestari DNA were each detected in nearly 2% of tick specimens. In white-tailed deer, 7.3% were PCR positive for E. chaffeensis, 6.0% for E. ewingii, and 3.2% for rickettsial species. Approximately 45% of white-tailed deer specimens had antibodies to Ehrlichia spp., and <1% had antibodies to Borrelia burgdorferi In summary, E. chaffeensis, E. ewingii, and spotted fever group rickettsia are highly prevalent in host-seeking lone star ticks and in white-tailed deer in Florida. The molecular and serological evidence of these microbes underscore their zoonotic potential in this region.