Tick-borne Disease Risk along the Appalachian Trail

Shelus, Victoria

National Parks, created to protect natural and historic landmarks, and characterized by unique, preserved ecosystems, attract many visitors from around the world. These visitors, as well as employees, frequently engage in a variety of outdoor activities that allow for close contact with animal and plant diversity. As a result, they may experience greater exposure to ticks that transmit human pathogens and cause disease. This paper assesses tick-borne disease risk in the National Park Service (NPS) units located along the Appalachian Trail: Delaware Water Gap National Recreation Area, Harpers Ferry National Historical Park, Chesapeake and Ohio Canal National Historical Park, Shenandoah National Park, the Blue Ridge Parkway, and Great Smoky Mountains National Park. It focuses on three tick vectors: Ixodes scapularis, the Black-legged tick or Deer tick, Amblyomma americanum, the Lone star tick, and Dermacentor variabilis, the American dog tick or Wood tick. Since the distribution of tick vectors is related to environmental factors, land cover, landscape structure, and elevation were quantified for the national park service units and the surrounding residential areas to determine their similarity and the possibility for the transferability of risk estimates. Differences with the percentage of forested area and the amount of edge habitat were found to be statistically significant. As a result, data from tick sampling in the NPS units is needed to estimate disease risk. However, the current knowledge on the abundance, infection prevalence, and seasonal phenology of ticks along the Appalachian Trail is insufficient and outdated. The true risk of tick-borne diseases in national parks is unknown, and likely under recognized. It is recommended that tick sampling as part of a larger tick-borne disease surveillance program be implemented in the national parks. As a starting point to further study, general tick habitat suitability was modeled for the NPS units along the Appalachian Trail based on land cover, elevation and moisture. Potential tick sampling sites were selected based on areas of high tick habitat suitability and high visitor use.

Tick-borne Disease Risk along the Appalachian Trail

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