DrPH (Doctor of Public Health)
Date of Award
Committee Chair or Co-Chairs
Phillip Scheuerman, Bill Brooks
Tick populations have been immigrating into northeast Tennessee from east Tennessee, Kentucky, Virginia, and North Carolina. Counties in states bordering northeast Tennessee harbor tick species associated with human illness. Human diseases transmitted by ticks include ehrlichiosis, spotted fever rickettsial group diseases, tularemia, anaplasmosis, babesiosis, Lyme disease, alpha-gal syndrome, Heartland virus, Powassan virus, and southern tick-associated rash illness (STARI). These diseases cause morbidity and mortality in human populations and may pose a high risk to individuals, wildlife, and livestock. The Cherokee National Forest covering the east Tennessee border provides a permissible environment for ticks to immigrate and thrive. Residents of northeast Tennessee frequently use the natural environment for a variety of purposes, creating exposure risk at the human-animal-environment interface.
This study performed a scoping review and meta-analysis addressing topics informing epidemiological investigation of tick populations. The meta-analysis identified geography, climate, and Shannon-Wiener Diversity Index as the most significant variables associated with northeast Tennessee tick populations. Additionally, tick surveillance in northeast Tennessee counties was performed. These counties included Carter, Greene, Hancock, Hawkins, Johnson, Washington, and Unicoi. Primary tick species present in the summer included the American Dog tick (Dermacentor variabilis); the winter included the Blacklegged/Deer tick (Ixodes scapularis). Canonical correlation analysis was used to identify which environmental variables had the most influence, to what degree, and in a positive or negative direction. Altitude, total forest land, forest canopy, and fraction of surface water area were statistically significant. More altitude was correlated with more clinical cases; less total forest land, canopy, and fraction of surface water area was correlated with less clinical cases. Lastly, species distribution modeling of the invasive Asian longhorned tick was conducted. Study results indicate a low to moderate risk for tick-borne illness exposures among human populations, which is poised to increase. Species distribution modeling and clinical case data reports suggested an increasing exposure risk from improved habitat suitability. Increased risk is related to climate change and tick population growth in metropolitan areas. Finally, surveillance and control methods are summarized for integration into public health interventions.
Dissertation - embargo
Schultz, Jacob, "Emerging Tick-Borne Diseases in Northeast Tennessee" (2023). Electronic Theses and Dissertations. Paper 4163. https://dc.etsu.edu/etd/4163
Copyright by the authors.
Available for download on Saturday, June 15, 2024