Survey of tick species and molecular detection of selected tick-borne pathogens in Yanbian, China

Ticks and tick-borne diseases pose a significant threat to public health. In this study, we aimed to determine the tick species distribution and pathogens carried by ticks in Yanbian, China. A total of 2673 questing ticks were collected from eight counties and cities in Yanbian and were morphologically identified. The presence of Candidatus Rickettsia tarasevichiae (CRT), spotted fever group Rickettsia (SFGR), severe fever thrombocytopenia syndrome virus (SFTSV), Theileria, and other pathogens was confirmed using polymerase chain reaction (PCR) and real-time quantitative PCR assays, followed by phylogenetic and genotypic analyses. According to the morphological identification, the tick species in Yanbian consisted of Haemaphysalis longicornis, Ixodes persulcatus, Dermacentor silvarum, H. japonica, and H. concinna. In H. longicornis, CRT, SFGR, SFTSV and Theileria orientalis were detected, while CRT, SFGR, and SFTSV were detected in I. persulcatus, H. japonica, and D. silvarum. Only SFTSV was detected in H. concinna. Mixed infection with CRT and SFTSV was observed in I. persulcatus and H. japonica. The gene sequences of all tested pathogens exhibited 95.7%-100% identity with the corresponding sequences deposited in GenBank. Phylogenetic analysis showed that different SFGR and SFTSV genotypes were closely related to the Korean strains. This study is the first to describe the genetic diversity of SFGR Candidatus Rickettsia longicornii in H. longicornis in Yanbian, China, using the ompA, ompB, sca4, and rrs genes. These results provide epidemiological data to support the prevention and control of ticks and tick-borne diseases in the border areas of China, North Korea, and Russia.