Molecular detection, phylogenetic relationships, and haplotype diversity of spotted fever group Rickettsia species in ticks collected from sheep and goats in Türkiye

Erol U., Şahin Ö. F., Kalın R., Urhan O. F., Şakar H. F., Altay K.

COMPARATIVE IMMUNOLOGY, MICROBIOLOGY AND INFECTIOUS DISEASES, cilt.129, ss.1-13, 2026 (SCI-Expanded, Scopus)

Özet

Species in the Rickettsia genus are among the oldest known vector-borne pathogens and represent a significant threat to both human and animal health. There is limited information on the epidemiology and phylogenetic characteristics of species in the Rickettsia genus in Türkiye. This study aimed to investigate Rickettsia species in sheep and goats, as well as in ticks collected from these animals, in Tokat, Samsun, Giresun, and Sivas provinces of Türkiye, with diverse climatic and geographical characteristics, and to determine their phylogenetic characteristics using molecular methods. For this purpose, blood and tick samples were collected from 789 animals, including 378 sheep and 411 goats. Rickettsia DNA was not detected in blood samples. Seven tick species, Hyalomma marginatum, Hyalomma anatolicum excavatum, Hyalomma detritum, Rhipicephalus bursa, Rhipicephalus turanicus, Dermacentor marginatus, and Haemaphysalis sulcata, were detected on the examined animals. A total of 486 ticks were collected from 175 animals (83 sheep and 92 goats), and 136 tick pools were prepared. Among them, 28.67% (39/136) were found to be infected with Rickettsia species. Five Rickettsia species, Ri. aeschlimannii, Ri. slovaca, Rickettsia sibirica subsp. mongolitimonae, Ri. raoultii, and Ca. Rickettsia barbariae, were identified. In this study, the tick species in which Rickettsia DNA was detected most frequently was Hyalomma marginatum. Sequence analyses of ompA and gltA gene regions of all positive samples were done, and the obtained consensus sequences were deposited in GenBank. Detailed phylogenetic analyses of the ompA and gltA gene regions of positive samples were conducted, and it was determined that multiple Rickettsia haplotypes circulate among hosts. Haplotype and network analyses revealed rapid expansion and/or negative selection in Rickettsia populations. Considering the zoonotic potential of the identified Rickettsia species, it is concluded that active pathogen surveillance and vector control programs involving both veterinarians and physicians are necessary to prevent losses caused by these pathogens.