Occurrence of Borrelia miyamotoi in Ixodes ricinus and Dermacentor reticulatus ticks removed from human skin in Poland in 2022–2024

Borrelia miyamotoi is an emerging human tick-borne pathogen that has been confirmed in multiple tick species, including Ixodes ricinus and Dermacentor reticulatus. In 2022–2024, 2263 ticks removed from human skin were collected for research, mainly of two species: I. ricinus (2123) and D. reticulatus (137). Detection of B. miyamotoi was performed by PCR, amplifying a fragment of the p66 and gplQ genes, confirmed by sequencing. In total, the pathogen prevalence in human-derived ticks was 3.0%. Among 63 positive I. ricinus (3.0%), B. miyamotoi was detected in females and nymphs with prevalence 3.5% and 2.9%, respectively. Four females of D. reticulatus were found to be infected with B. miyamotoi, and the infection rate was 2.9%. More than 65% of positive ticks were classified as semi-engorged. Among I. ricinus in which B. miyamotoi was detected, co-occurrence with Borreliella burgdorferi sensu lato was found in 15 cases (23.8%), with Borreliella afzelii being the most common species. Based on the obtained results, the prevalence of B. miyamotoi in tested ticks was considered low; however, studies on the occurrence of this pathogen in ticks should be continued.