Detection of US and Kobe-type Babesia microti in ticks collected from small mammals of the Republic of Korea

Human babesiosis is an emerging tick-borne zoonotic disease prevalent in large parts of the world. This study aimed to examine the status of Babesia microti infection in ticks collected from small mammals captured during the nationwide survey of the Republic of Korea (ROK), 2017. Ixodid ticks from small mammals of three species, Apodemus agrarius, Crocidura lasiura, and Tscherskia triton, were used for the molecular detection of B. microti. PCR analyses amplifying 18S ribosomal RNA (rRNA) of the genus Babesia showed 8.4% of the ticks to be positive. Nucleotide sequencing of the PCR products revealed two different genotypes of B. microti, the US and Kobe-type. The US-types of B. microti were detected in ticks from small mammals of almost all study sites, whereas detections of Kobe-types were restricted to ticks from southern part of ROK. Phylogenetic analysis also indicated that each of the two types of B. microti clustered into two distinct clades. This is the first report on the presence of the US and Kobe-type B. microti in ticks collected from small mammals trapped on a national scale in ROK.