New problems of environmental ecology: ticks and tick-borne pathogens in city parks of Ukraine

Rickettsia Species: Genetic Variability, Vectors, and Rickettsiosis-A Review

Rickettsiae are an interesting group of bacteria comprising a large number of obligate intracellular species. The circulation of these bacteria in the environment depends on the presence of vectors (blood-sucking invertebrates) and their hosts. On the basis of phylogenetic analyses in 2022, a division into five groups of Rickettsia has been proposed: I belli group, II canadensis group, III typhus group, and IV and V spotted group fever (respectively II, phylogenetically older, and I). The genus Rickettsia includes species that are both pathogenic and nonpathogenic to humans and domestic and wild animals. Some Rickettsia species are invertebrate symbionts. Currently, rickettsiae, which are transmitted mainly by ticks, are spreading worldwide. This has been promoted by climate change, environmental changes caused by humans, and the synanthropisation of plants and animals. Therefore, it is extremely important to monitor the natural and urban environments. The study of potential vectors and reservoirs of bacteria in the genus Rickettsia should be a permanent part of the analysis of the modern human environment.

A New Endemic Locality of Dermacentor reticulatus in Central-Southern Poland and Its Potential Epidemiological Implications

Dermacentor reticulatus (Acari: Ixodidae) is an important arthropod vector in medical and veterinary contexts. Its geographic range is divided into western and eastern populations separated by a "Dermacentor-free zone" in central Poland. Recent faunistic studies showed a new endemic locality of the species in Upper Silesia to the west of the Vistula River (central-southern Poland) and its co-occurrence with I. ricinus. The prevalence of five tick-borne pathogens (TBPs), e.g., B. burgdorferi s.l., Bartonella spp., Rickettsia spp., and Babesia spp., in the ticks was assessed with polymerase chain reaction (PCR) methods. The molecular studies revealed the presence of Rickettsia spp. in 23.8% of the D. reticulatus specimens. In turn, 94.1% of the I. ricinus adults were infected with B. burgdorferi s.l., 11.7 % with Babesia spp., and 5.8% with Rickettsia spp. Coinfections with two TBPs were noted in 17.6% of the I. ricinus. These findings highlight not only the risk of infestation by both tick species in an area previously considered Dermacentor-free, but also the high prevalence of TBPs in the study area. Increased focus on medical and veterinary services appears necessary to diagnose and prevent tick-borne diseases in this region.