Molecular identification of pathogens in ticks collected in South Korea

Abstract

Abstract Introduction: Ticks are considered the main arthropod vectors for infectious disease agents. They are related to veterinary and medical health issues. Studying the regional difference of pathogen detection rate in ticks is an essential factor in developing and initiating prevention strategies. Methods: This study focuses on investigation of tick-borne pathogens from the ticks collected in vegetation by flagging. The morphological examination was performed for tick species and their developmental stages (Haemaphysalis longicornis and Haemaphysalis flava). For bacteria and protozoa detection, 109 tick samples from Wonju, Gunsan, and Yangsan were collected during August 2014-2016, undergone DNA extraction. Detection for specific bacteria and protozoa using pathogen-specific PCR methods has been done mostly; Rickettsia spp. was identified using gltA and ompA primers. For severe fever with thrombocytopenia syndrome (SFTS) virus detection, RNA of 50 tick samples from Samcheok (April 2020) was extracted to perform reverse transcription-PCR using the virus-specific primer. The amplicon product has been sequenced, and the results were compared with the Basic Local Alignment Searching Tool (BLAST) using NCBI database for identification. Results: Among 109 ticks examined, the detection rate for bacterial and protozoal has been recorded as 32(29.35%). The detection rate for the specific pathogens was 19.26% for Rickettsia japonica, 1.83% for Coxiella burnetii, and 8.25% for Theilleria luwansheni, respectively. From total samples which were examined, one mixed infection was observed between Rickettsia japonica and Theilleria luwansheni from the collection site of Wonju, while Anaplasmataceae, Borrelia spp., and Bartonella spp. were not identified. The viral pathogen for SFTS were examined in 50 tick samples from the Samcheok site, but all the results of their RNA extraction were negative. Conclusion: H. longicornis had a higher pathogen detection rate than H. flava. Rickettsia japonica, Coxiella burnetii, Theilleria lunwenshuni were detected among the selected pathogens. T. lunwenshuni were detected in ticks collected in Wonju among the target protozoa. In H. longicornis, Rickettsia japonica was the most frequently detected in Wonju, Gunsan and Yangsan among other targeted pathogens (Anaplasmataceae, Borrelia spp, Bartonella spp, and, SFTS v). The information in this study may provide important information to inform the nearby community, human and animal’s health sectors in order to activate surveillance and monitoring against tick-borne pathogen about the possible emergence should be cautiously monitored. Further research and routine surveillance would be important for mitigation the disease prevalence and controlling the transmission in all stages.