Distribution of Borrelia burgdorferi sensu lato in micromammals in the Republic of Korea

Lyme disease is a vector-borne zoonotic disease caused by spirochete bacteria of the genus Borrelia . It is primarily transmitted by ticks of the genus Ixodes . Vertebrate hosts, including rodents and insectivores such as shrews and moles, maintain the pathogens in ecosystems. Research on the prevalence and geographical distribution of Borrelia species and other micromammal-associated zoonotic pathogens in the Republic of Korea (ROK) is scarce. This study investigated the prevalence and distribution of Borrelia spp . in wild micromammals across the ROK to support Lyme disease control. In this study, we collected 200 spleen samples from micromammals in 14 regions nationwide, including Apodemus agrarius, Crocidura sp., Micromys minutus, and Apodemus peninsulae . Genomic DNA was extracted from the spleen tissues, and PCR and phylogenetic analyses targeting flagellin B ( flaB ), outer surface protein A ( ospA ), and 5S-23S rRNA intergenic spacer (5S-23S) were performed. Phylogenetic analysis based on flagellin B ( flaB ), outer surface protein A ( ospA ) and 5S-23S rRNA intergenic spacer (5S-23S) sequences revealed distinct clustering of Borrelia afzelii, Borrelia yangtzensis and a lineage designated as Borrelia sp. B. afzelii was predominantly detected in northern and central regions of the ROK, whereas B. yangtzensis was mainly present in the southern region of the ROK. This study provides updated insights into the prevalence and spatial distribution of Borrelia spp. in Korean micromammals. Our findings contribute to a better understanding of wildlife reservoirs and may inform future strategies to prevent and control micromammal-borne zoonoses.