First report of the molecular detection of human pathogen Rickettsia raoultii in ticks from the Republic of Korea

Background Rickettsial diseases associated with the spotted fever group constitute a growing number of newly identified Rickettsia pathogens and their tick vectors in various parts of the world. At least 15 distinct tick species belonging to six genera have shown the presence of Rickettsia raoultii. Herein, we report the detection of R. raoultii in ticks from the Republic of Korea (ROK). Methods Thirty-five ticks were collected from 29 patients with tick bites in Gwangju Metropolitan City, Jeollanam Province, ROK. The ticks were identified using molecular, morphological, and taxonomic characteristics. All samples were screened for presence of Rickettsia species using nested polymerase chain reactions of their outer membrane protein (ompA) and citrate synthase (gltA) genes. The amplified products were sequenced for subsequent phylogenetic analyses. Results Sequencing data showed the DNA sequences of R. raoultii in three Haemaphysalis longicornis ticks. All three tick samples were 99.4-100% similar to previously reported partial sequences of ompA of R. raoultii strains CP019435 and MF002523, which formed a single clade with the reference strains. Conclusions We provide the first description and molecular identification of R. raoultii detected in H. longicornis ticks in the ROK. This observation extends the geographical distribution of R. raoultii. Screening of human samples for this pathogen will provide information about the prevalence of rickettsial infections in this region.