Community-engaged passive tick surveillance highlights the diversity of ticks and tick-borne pathogens in Illinois

The continuing increase in incidence of tick-borne illnesses in the United States necessitates expanded surveillance, especially in areas like Illinois experiencing range expansion of key vectors such as Ixodes scapularis and Amblyomma americanum . We report on the initial years (2018–2023) of a community-engaged passive tick surveillance program in Illinois designed to complement active collections by casting a wide net for tick species, tick-host encounters, and emerging pathogens. Participants submitted eight tick species, dominated by A. americanum , I. scapularis , and D. variabilis . Submissions, primarily adults, occurred almost year-round (except February), and were most often associated with humans, dogs, and deer. We used a microfluidic system and sequencing to test a subset of the submitted ticks. Six tick-borne pathogens were detected, including Borrelia burgdorferi s.s. (14% prevalence in adult I. scapularis ), B. miyamotoi (4.7% in adult I. scapularis ), and Anaplasma phagocytophilum (1.2% in I. scapularis as well as 1 out of 7 tested Dermacentor albipictus ). We also documented spotted fever group Rickettsia species, such as R. amblyommatis (53% prevalence in nymphal A. americanum ), R. montanensis (2.1% in D. variabilis ), and Candidatus R. andeanae (in 2 out of 3 A. maculatum ). These efforts helped document the year-round risk of tick exposure and expanded our knowledge of the diversity of ticks and circulating pathogens in Illinois. We believe the combination of a sustainable, low-cost passive surveillance program coupled with multi-pathogen assays can serve a useful function as complementary surveillance for emerging pathogens and changing tick distributions.