Comparative evaluation of Amblyomma americanum and Dermacentor variabilis microbial agents and human disease case data in seven Piedmont counties of North Carolina, 2020-2023.

Tick-borne pathogens pose an ongoing threat to human health in the southeastern United States, where tick and host abundances are high. In North Carolina, several medically important tick species are present, but in the Piedmont region, Amblyomma americanum is particularly abundant and associated with multiple human pathogens, including Rickettsia amblyommatis, a hypothesized human pathogen. In this study, we build on recent tick surveillance efforts across several North Carolina counties by screening A. americanum for Ehrlichia ewingii, Ehrlichia chaffeensis, and R. amblyommatis while also analyzing tick abundance, pathogen prevalence, and county-level human disease case data from the North Carolina Department of Health to assess potential correlations. Our results reveal variation in pathogen prevalence across counties, with Chatham County consistently emerging as a high-risk area due to high tick abundance and elevated infection rates. However, we did not observe a strong correlation between tick abundance or pathogen prevalence and reported human disease cases at the county level. These findings highlight counties of elevated risk in a region experiencing an increasing burden of tick-borne disease and contribute to our understanding of ongoing public health trends.