Comparative microbiome analysis of Haemaphysalis longicornis ticks at the Korea Combat Training Center in 2022

The Korea Combat Training Center (KCTC), located in Gangwon Province, is a restricted military training facility where research on the environmental conditions and health risks to military personnel has been limited. In this study, using iSeq 100, we investigated the bacterial abundance and microbiome of Haemaphysalis longicornis specimens collected at the KCTC from June to August 2022, to assess current and potential public health risks to military personnel. Our results show that adult ticks had significantly greater species richness compared with larvae and nymphs, with no notable differences in diversity across developmental stages. Principal coordinate analysis of the microbial communities did not show differences attributable to any single factor, such as collection location or date. Coxiella-like endosymbionts (AB001519) were identified in all 13 samples, and Jatrophihabitans, Sphingomonas, and Spirosoma were consistently found across all samples. In addition, iSeq 100 also identified Rickettsia rickettsii and Borrelia spp., which were not detected with conventional polymerase chain reaction (PCR).