Emerging Tick-Borne Disease Risk in an Urban Center of Harris County, Texas

Background: Tick-borne diseases are an endemic and emerging public health concern in the United States. Ongoing tick range expansion, invasive species, and newly identified pathogens are rapidly altering disease epidemiology. Surveillance is critical to understanding vector ecology and disease risk. Harris County, Texas, with nearly five million residents and diverse ecological zones, offers a unique setting to study local tick dynamics. Methods: From January 2021 to December 2022, we conducted weekly tick surveillance across 63 sites in Harris County (City of Houston), Texas. Ticks were morphologically identified and tested for Rickettsia, Borrelia, Ehrlichia, and Anaplasma via real-time PCR. Samples positive by initial screening were confirmed to the species level using endpoint PCR and sequencing. Results: We collected 1,219 ticks-primarily Ixodes scapularis and Amblyomma maculatum-with distinct seasonal and spatial patterns. Of 1,195 tested ticks, 61% were positive for Rickettsia, with multiple species identified. Notably, Rickettsia parkeri was detected in 23.1% of Rickettsia-positive A. maculatum ticks. Conclusion: Our findings reveal significant tick-borne pathogen activity in Harris County, highlighting the need for continued surveillance and public health efforts in urban and peri-urban Texas.