Pathogen and host associations of Ixodes scapularis (Acari: Ixodidae) in eastern Ohio 10 years post establishment.

The blacklegged tick (Ixodes scapularis) is a primary vector of medical concern in the eastern United States, capable of infesting a wide range of hosts. The first established population in Ohio was detected on rural residential properties in Coshocton County and has since expanded across the state. To assess current conditions, these index sites were revisited, and questing ticks were collected between 2019 and 2021, with small mammals sampled in 2021. Ticks and host tissues were screened for Borrelia burgdorferi sensu lato, Borrelia burgdorferi sensu stricto, Borrelia mayonii, and Anaplasma phagocytophilum. A total of 654 questing blacklegged ticks and 106 small mammals representing eight species were sampled. White-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus) were the most frequently infested hosts. Infection prevalence in ticks was 47.6% for B. burgdorferi sensu lato, 42.9% for B. burgdorferi sensu stricto, and 15.5% for A. phagocytophilum. Six of eight small mammal species tested positive, with infection prevalence of 60.4%, 19.8%, and 11.9% for the same pathogens, respectively. Borrelia mayonii was not detected. These infection prevalences are comparable to those reported in long-established Lyme-endemic regions in the northeastern and upper midwestern United States. Findings indicate that the enzootic Lyme disease cycle is now well established in parts of Ohio. Public health agencies should be aware of the increasing risk of tick-borne disease in the region, and these results support the importance of host-targeted interventions to reduce pathogen transmission and human disease risk.