Blacklegged ticks, Ixodes scapularis, can transmit single or multiple infections during a tick bite. These tick-borne, zoonotic infections can become chronic and cause insidious diseases in patients. In the present tick-pathogen study, 138 (48.9%) of 282 ticks collected from 17 sites in 6 geographic area in eastern Canada harbored various combinations of Borrelia burgdorferi sensu lato (Lyme disease), Anaplasma phagocytophilum (human anaplasmosis), and Babesia spp. (human babesiosis). Overall, 167 microbial infections were detected and, of these, 25 ticks had co-infections and two ticks had polymicrobial infections. The prevalence of Babesia spp. was 15.2%, and the ratio of Babesia odocoilei to Babesia microti was 41 to 1 with this sole B. microti being detected in Nova Scotia. Notably, we provide the first documentation of B. odocoilei in the Maritimes. Eastern Ontario had an infection prevalence for B. odocoilei of 25%-the highest among the areas surveyed in this study. By far, the predominant Babesia sp. was B. odocoilei. Based on our findings, health-care practitioners need to recognize that I. scapularis ticks removed from patients may be carrying multiple tick-borne pathogens.

The blacklegged tick, Ixodes scapularis, is known to carry various tick-borne zoonotic pathogens with the potential to cause debilitating human and animal diseases. Juvenile I. scapularis parasitize songbirds and, perhaps, these avifauna are competent hosts of common microbial pathogens. We extracted brachial venous blood from 18 ground-foraging passerine birds that were parasitized by I. scapularis larvae and nymphs. Using molecular identification, namely PCR, DNA sequencing, and Basic Local Alignment Search Tool (BLAST), we targeted Anaplasma phagocytophilum, Babesia spp. and Borrelia burgdorferi sensu lato. Overall, 15 (83%) of 18 passerine birds were positive for 3 microbial zoonotic pathogens that comprised of A. phagocytophilum (n = 8), Babesia odocoilei (n = 6), Babesia spp. 20-5A74 (n = 1), and B. burgdorferi sensu lato (n = 9). The pathogen load consisted of 8 singles, 5 doubles, and 2 triples. One novel Babesia sp. (Babesia spp. 20-5A74) was found, and the remaining Babesia infections were B. odocoilei. Our findings reveal that ground-foraging, passerine birds are avian hosts of zoonotic pathogens. We provide the first-ever documentation that songbirds are hosts of B. odocoilei. Based on our data, B. odocoilei outnumbered other Babesia spp., and elucidated the authentic fact that B. odocoilei is the predominant Babesia sp. in North America. As avian hosts, passerine birds play a significant role in the enzootic transmission cycle of B. burgdorferi sensu lato, A. phagocytophilum, and Babesia species.