Medical and veterinary pathogens detected in invading Asian longhorned ticks (Haemaphysalis longicornis) from Ohio and Pennsylvania.

Abstract

OBJECTIVE: To estimate the prevalence of medical and veterinary pathogens in invading Asian longhorned tick (ALT; Haemaphysalis longicornis) populations in 2 adjoining states, Ohio and Pennsylvania. METHODS: We conducted a cross-sectional study to test ALTs collected through active (probability-based) surveillance in Pennsylvania and active or passive (opportunistic) surveillance in Ohio for medical and veterinary pathogens using PCR. RESULTS: We collected 563 nymphs and adult females from 2021 through 2025 from the environment and domestic cows. We detected DNA of Anaplasma phagocytophilum (3 of 563 [0.53%]; 95% CI, 0.11 to 1.55). A subsample of ticks from both states was tested for Babesia spp. The DNA of Babesia spp was detected in Ohio (20 of 61 [32.79%]; 95% CI, 21.31 to 46.00;), and sequence data (from 8 samples) identified 4 detections of Babesia odocoilei and 4 detections of Theileria orientalis Ikeda. The DNA of Babesia spp was also detected in Pennsylvania (6 of 41 [14.63%]; 95% CI, 5.57 to 29.17); however, we were unable to retrieve any sequence data. CONCLUSIONS: Our findings, albeit partially based on opportunistic sampling, suggest that the epidemiology of ALT-associated pathogens is evolving as we detected medical and veterinary pathogens of concern, primarily in Ohio. Surveillance can help guide veterinary and public health professionals to inform management. CLINICAL RELEVANCE: To the best of our knowledge, this is the first reported detection of B odocoilei from host-seeking ALTs anywhere in the US and the first reported detection of T orientalis Ikeda from host-seeking ALTs in Ohio.