Park size and trail environment influence seasonal tick-borne pathogen transmission risk in Nashville metropolitan area parks, Tennessee

In Tennessee, vector tick species and tick-borne pathogen (TBP) distributions have been monitored for years, but acarological risk in metropolitan parks and recreational areas has not been assessed. Therefore, we evaluated tick and TBP presence, along with environmental and microclimatic factors influencing their occurrence in Davidson County parks. From June 2020 to June 2021, we collected 25,082 ticks via dragging from trail and forest environments across 24 parks, categorized by size from small to extra-large. Amblyomma americanum constituted 99.5% of collections, followed by Dermacentor variabilis, Amblyomma maculatum, and Ixodes scapularis. The highest proportion of pools positive for Ehrlichia ewingii and Panola Mountain Ehrlichia were in spring, while Ehrlichia chaffeensis were in summer, all in A. americanum nymphs from large parks. Rickettsia parkeri was identified in three A. maculatum adult pools from small parks in summer. A significant seasonal effect was detected for A. americanum, with peak adult (β = 0.54 ± 0.22; 95% CI [0.12–0.96]) and nymph (β = 1.28 ± 0.26; 95% CI [0.77–1.80]) counts observed in summer (June–August), and in large parks, with total counts moderately correlated with barometric pressure and relative humidity. Additionally, A. americanum nymph counts were significantly greater in forested areas (14.3 ± 3.01) as compared to trails (3.98 ± 0.56). Our findings indicate exposure risks for multiple vector tick species and presence of four TBPs within Davidson County parks, underscoring the importance of surveillance and management of recreational areas to mitigate tick-borne disease transmission opportunities in Tennessee's fastest-growing metropolitan area.