Molecular detection of Francisella tularensis and Rickettsia spp. in ticks collected on animals in the pasture, Edirne

Background : Ticks are important vectors of numerous zoonotic pathogens affecting both human and animal health. Rickettsia species are widely distributed tick-borne bacteria, whereas Francisella tularensis is a highly infectious zoonotic agent with focal ecological distribution. The Thrace region of Türkiye represents an epidemiological transition zone due to its geographical location and ecological characteristics. Methods : Between June and September 2023, ticks were collected from grazing cattle and sheep in the Keşan and İpsala districts of Edirne Province. A total of 540 ticks were morphologically identified and pooled in groups of ten according to species and collection area, resulting in 54 DNA pools. Molecular analyses were performed using polymerase chain reaction (PCR). The tul4 gene was targeted for the detection of F. tularensis , while the gltA , ompA , and 23S rRNA gene regions were targeted for Rickettsia spp. Positive samples were subjected to nucleotide sequencing for species-level identification. Results : The collected ticks were identified as Rhipicephalus sanguineus (61.9%), Rhipicephalus annulatus (29.8%), and Hyalomma marginatum (8.3%). No PCR positivity was detected for F. tularensis . In contrast, Rickettsia spp. DNA was detected in 8 of the 54 pools (14.8%). Sequence analysis identified Candidatus Rickettsia barbariae and Rickettsia massiliae . Positivity was predominantly observed in Rhipicephalus species, indicating the circulation of multiple Rickettsia species within shared ecological niches in the region. Conclusions : This study demonstrates the molecular presence of tick-borne Rickettsia species in the Thrace region of Türkiye and highlights the region as an active ecological area for rickettsial circulation. Although F. tularensis was not detected, the continued risk of tularemia through environmental and waterborne transmission should not be overlooked. These findings emphasize the importance of integrated, One Health–based molecular surveillance programs to assess and mitigate zoonotic risks in Thrace and neighboring Balkan regions.