Occurrence of tick-borne pathogens in questing ticks, ticks from riding horses, and red deer blood in Western Pomerania, Poland

Ixodes ricinus is a widespread vector of numerous microorganisms pathogenic to humans and animals in Europe. The risk of exposure to tick-borne pathogens (TBPs) has increased in recent years due to climate change, the conversion of natural green areas to recreational areas, and growing human and animal populations, including pets. Using molecular methods, the prevalence, diversity, and co-occurrence of selected tick-borne microorganisms were assessed in questing I. ricinus collected from recreational areas (n = 409), in ticks feeding on horses (n = 135), and in blood samples from red deer (n = 42) in northwestern Poland. In ticks, Borrelia afzelii (15 %), B. garinii (14 %), other Borrelia spp. (25.2 %), Anaplasma phagocytophilum (4.6 %), Rickettsia helvetica (11 %), R. raoultii (0.5 %) and R. monacensis (0.3 %) were identified. In deer blood samples, B. garinii (2.4 %), Borrelia spp. (4.8 %), A. phagocytophilum (9.5 %) and R. helvetica (4.8 %) were detected. Dual co-detection were observed, including B. afzelii and Borrelia spp. (8.3 %), Rickettsia spp. and Borrelia spp. (2.4 %), Anaplasma spp. and Borrelia spp. (0.9 %), in questing ticks, in ticks collected from horses, and in the deer blood samples. One triple pathogen co-detection (Borrelia spp., A. phagocytophilum, and R. helvetica; 0.2 %) was identified in questing ticks, and two quadruple pathogen combinations involving A. phagocytophilum or R. helvetica with different Borrelia spp. were detected in deer blood (0.3 %) and ticks feeding on horses (0.6 %), respectively.These findings highlight a substantial risk of exposure to multiple TBPs in forested recreational areas and underscore the potential for the simultaneous acquisition of at least two pathogens.