Diversity of Borrelia spirochetes and other zoonotic agents in ticks from Kyiv, Ukraine.

Lyme borreliosis (LB) is caused by tick-borne spirochetes of the Borrelia burgdorferi sensu lato complex. LB is the most prevalent vector-borne illness in Ukraine, but current data on the prevalence of LB pathogens in their tick vector, Ixodes ricinus, are lacking. I. ricinus ticks may also carry Borrelia miyamotoi, an emerging relapsing fever group spirochete that has been implicated in human illness. Despite its zoonotic potential, the prevalence of B. miyamotoi in ticks has not been examined in Ukraine. Similarly, data on the prevalence of other important tick-borne pathogens, Anaplasma phagocytophilum, Babesia spp., Bartonella spp., Francisella tularensis, and Rickettsia spp., in ixodid ticks are scarce or even absent. Thus, the overall objective of this study was to investigate the prevalence of these tick-borne pathogens in questing I. ricinus and Dermacentor reticulatus ticks collected in recreational parks of Kyiv, the most densely populated city of Ukraine. A total of 182 adult I. ricinus, 98 nymphal I. ricinus, and 98 adult D. reticulatus ticks were molecularly analyzed for the presence of these pathogens. As a result, the study shows a greater diversity of Borrelia genospecies in questing I. ricinus ticks than previously reported. The most prevalent genospecies in adult I. ricinus ticks were B. afzelii (7.7%), followed by B. burgdorferi sensu stricto (s.s.) (2.2%) and B. garinii (0.5%). In contrast, B. burgdorferi s.s. was most dominant in unfed I. ricinus nymphs (67.3%). Moreover, B. afzelii was detected in 11.2% of nymphs, but only 1.0% of nymphal ticks were positive for B. garinii and B. valaisiana. Importantly, this study provides the first record of B. miyamotoi detected in I. ricinus ticks from Ukraine (1.1%). Furthermore, the report is also the first to document other vector-borne pathogens, Bartonella henselae, Rickettsia conorii, and Rickettsia mendelii, in ixodid ticks from Ukraine. In summary, this work offers the latest data on the diversity and prevalence of the important zoonotic tick-borne agents in questing ticks from Kyiv, Ukraine. The data will help to better gauge the risk associated with vector-borne infections to which residents and guests of Ukraine's capital may be exposed.
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