Diversity and prevalence of spotted-fever group rickettsiae in ixodid ticks across Slovakia, Central Europe

Habitats with the sympatric occurrence of several ixodid tick species are significant from an epidemiological perspective. These habitats can influence the diversity and prevalence of tick-borne pathogens, and their monitoring can help estimate the risk of infection. A total of 1260 questing ticks from five species (Ixodes ricinus, Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis concinna, and Haemaphysalis inermis) were collected from vegetation using the flagging method in three different habitats in eastern Slovakia. Additionally, 900 rodent-attached ticks of six species (I. ricinus, Ixodes trianguliceps, D. marginatus, D. reticulatus, H. concinna, and H. inermis) collected from 149 small mammals belonging to seven species (Apodemus flavicollis, Apodemus agrarius, Microtus arvalis, Myodes glareolus, Micromys minutus, Crocidura leucodon, and Crocidura suaveolens) were selected for molecular analyses. DNA obtained from rodent-attached and questing ticks was tested by nested PCR targeting the gltA gene to determine the presence of Rickettsia spp. The ompA, ompB, and sca4 genes were amplified and sequenced to identify rickettsiae species. The overall prevalence of rickettsiae in questing and rodent-attached ticks was 12.5 % and 20.0 %, respectively. Overall studied localities, the most diverse spectrum of rickettsiae species, including R. helvetica, R. monacensis, R. raoultii, and R. slovaca, was recorded in questing and rodent-attached ticks in the natural habitat of the Slovak Karst. The dominant species, R. helvetica (62.9 %), was identified in two species of questing and rodent-attached ticks, specifically I. ricinus and H. concinna, and in rodent-attached D. reticulatus ticks. Rickettsia raoultii (20.4 %) was identified in questing and rodent-attached D. marginatus, D. reticulatus, and in questing H. concinna. Additionally, this study provides the first input of pathogenic R. raoultii in I. trianguliceps obtained from the striped field mouse (A. agrarius). Rickettsia monacensis (9.0 %) was detected in questing and rodent-attached I. ricinus, while Rickettsia slovaca (3.6 %) was found in questing and rodent-attached D. marginatus ticks. Natural biotopes with different tick species and hosts significantly affect the diversity and prevalence of rickettsiae.