Researchers have gradually begun to learn more about the biology and ecology of Ornithodoros turicata: a soft tick found in the southeastern and southwestern United States. Known as the “relapsing fever tick,” Ornithodoros turicata poses medical concerns because it serves as a vector for tickborne pathogens, such as relapsing fever spirochetes and African Swine Fever virus.
“In Florida, we know very little about this tick,” said Sebastian Botero-Cañola, who works in the Wisely Lab at the University of Florida Department of Wildlife Ecology and Conservation.
Botero-Cañola, a postdoctoral associate at the UF College of Agricultural and Life Sciences, won first place in the post-doctoral poster competition at EPI Research Day 2024. His research aims to model the distribution of Ornithodoros turicata in the state of Florida and across the southeastern United States. Understanding the spread of the tick will help detect potential risks of disease transmission to humans, livestock and wildlife, primarily domestic and feral pigs.
“We ended up with about four pounds of soil and debris,” Botero-Cañola said. “Then in the lab, we sifted through and detected [the ticks]. What’s super cool about this is that [the ticks] glow under UV light.”
Botero-Cañola and the team traveled from South Florida to North Florida, observing different climates and habitats throughout the state to collect soil samples from gopher boroughs. The team found the peaks throughout the state and used the gathered information to create a framework that associated the presence of the ticks with certain environmental variables.
“I think the most important result is that we found that the tick is distributed throughout the state, we detected it in more than 50% of the surveyed sites,” Botero-Cañola said.
Their results show that 85% of Florida’s land area consists of habitat suitable for Ornithodoros turicata. This emphasizes the necessity for predicting the spread of the ticks and establishing procedures to prevent the introduction of African Swine Fever to the state. The tick-borne virus has not had a recorded case in the United States but is widespread across Africa, Europe and Asia and has recently been detected in the Caribbean.
“I want to improve our understanding of the ecology of Ornithodoros turicata for medical and veterinary reasons,” Botero-Cañola said. “I want to leave a better understanding of the environmental requirements of the tick and provide tools for agriculture and public health officials to manage the risk imposed by the pathogens transmitted by this tick”
When discussing his win, Botero-Cañola credited the great efforts of everyone in the Wisely Lab, as well as his wife for helping him with his research poster. The team is in the final stages of the project, mapping out the distribution of Ornithodoros turicata. They hope to soon publish their results on the biology and ecology of the ticks.
The geographic distribution and environmental drivers of Ornithodoros turicata through the southeastern united states
Collaborators
- Sebastian Botero-Cañola – Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, College of Agricultural and Life Sciences, University of Florida
- Carson Torhorst – Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, College of Agricultural and Life Sciences, University of Florida
- Nicholas Canino – Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, College of Agricultural and Life Sciences, University of Florida
- Kathleen O’Hara – Center for Epidemiology and Animal Health, Veterinary Services, Animal and Plant Health Inspection Service, USDA
- Angela James – Center for Epidemiology and Animal Health, Veterinary Services, Animal and Plant Health Inspection Service, USDA
- Samantha Wisely – Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, College of Agricultural and Life Sciences, University of Florida
Abstract
The soft tick Ornithodoros turicata (O.t.) is a component vector for African Swine Fever (ASF), a globally spreading viral disease affecting wild and domestic swine. Despite its epidemiological importance, there are large gaps in our understanding of the distribution and ecology of O.t. This is especially true for Florida, where only a handful of published occurrence records of the species exists, yet the risk of ASF introduction and establishment is high. In this work, we integrated historical occurrence data with systematic surveys to i) predict the distribution of O.t. over the southeastern USA; and ii) Assess the influence of environmental conditions over habitat suitability for this species. Our sampling targets to evaluate the occurrence of O.t were the burrows of gopher tortoises, the preferred microhabitat of this tick in the region, and which we surveyed by vacuuming a soil sample from its interior. We Employed data on the detection probability of O.t to determine the number of sites to survey and the sampling intensity per site required to optimally cover Florida’s environmental gradients while maximizing the odds of detecting the tick.
This resulted in a sampling scheme comprising the survey of five burrows at 100 sites. This effort allowed the detection of O.t. at 58 sites, notably increasing the occurrence records for the eastern population of the species. Using these records, in conjunction with GIS layers describing climatic conditions and soil composition, we created a Maxent model to predict habitat suitability for the species through the Southeastern USA. The model displayed a good performance at predicting the species distribution (ROC-AUC = 0.96) and suggests that 85% of Florida presents suitable conditions for the species. O.t is predicted to occur north of Lake Okechoobee and east of the western extreme of the panhandle. In addition, southeastern Georgia presents a block of suitable habitat. Through a Jackknife analysis, we found that soil composition in addition to precipitation seasonality and temperature are key variables in shaping the distribution of the species. This work highlights the importance of tick surveillance in the event of ASF introduction as the broad distribution and prevalence of O.t. over the landscape, in addition to large populations of feral swine, may enhance the risk of the sylvatic establishment of this pathogen.