Molecular Prevalence of Blastocystis sp. from Patients with Diarrhea in the Republic of Korea

Blastocystis sp. is the most common intestinal protozoan affecting human health worldwide. Several studies have reported the prevalence of Blastocystis sp. in various regions of the Republic of Korea. However, limited data are available on the prevalence and subtype (ST) distribution of this parasite among regions. Therefore, we investigated the prevalence and ST distributions of this parasite in the Republic of Korea. For this purpose, 894 stool specimens were collected from patients with diarrhea and tested for the presence of Blastocystis sp. using PCR analysis. The isolates were subsequently subtyped. The overall prevalence was 11.6%. Of the 104 isolates, ST3 was the most prevalent, followed by ST1. Additionally, a single case of the rare subtype ST8 was identified, representing the first reported case in the Republic of Korea. The results suggested that the predominance of ST3 observed in this study reflects human-to-human transmission with low genetic diversity within the ST, while ST1 transmission is likely correlated with animals. In the future, to better understand Blastocystis sp. transmission dynamics, human, animal, and environmental factors should be studied from a "One Health" perspective.