Molecular Investigation of Tick-Borne Pathogens in Ticks removed from Tick-Bitten Humans in the Republic of Korea

Abstract

Background Tick-borne infections are continuously increasing due to climate change, increased outdoor activities and increased travel between countries. This study was to investigate the presence of tick-borne pathogens in ticks removed from tick-bitten humans in southwest provinces of Republic of Korea (ROK). Methods Ticks were obtained from those tick-bitten humans between May 2014 and September 2017 in Jeollanam provinces and Gwangju metropolitan city in ROK. The presence of the tick-borne pathogens in ticks removed from tick-bitten humans was analyzed using pathogen-specific polymerase chain reaction (PCR). Results We identified 33 ticks from three tick species, namely Amblyomma testudinarium (60.6%), Haemaphysalis longicornis (27.3%), and Ixodes nipponensis (12.1%) in order of occurrence by morphology and 16S rDNA-targeting PCR. Tick-borne pathogens were found in 16 ticks using pathogen-specific PCR. From the results, 12 ticks (36.4%) tested positive for spotted fever group (SFG) Rickettsia: Rickettsia monacensis (1/12), R. tamurae (8/12), and Candidatus Rickettsia jingxinensis (3/12). Three ticks (9.1%) were positive for Anaplasma phagocytophilum . In addition, three ticks (9.1%) tested positive for Babesia gibsoni (1/3) and B. microti (2/3). Conclusions In conclusion, we identified three tick species; the most common species was A. testudinarium followed by H. longicornis and I. nipponensis . SFG Rickettsia , A. phagocytophilum , and Babesia spp. were the most frequently detected pathogens in ticks removed from tick-bitten humans. R. tamurae and Ca. R. jingxinensis were firstly detected in Korea. The present results will contribute to the understanding of tick-borne infections in animals and humans in the ROK.