Molecular Detection and Subtyping of Blastocystis Detected in Wild Boars (sus Scrofa) in South Korea

Blastocystis is a genus of parasitic protozoans that live in humans, mammals, and birds and which has been widely studied due to its low host specificity. Limited data are available, however, regarding its presence in wildlife, particularly in South Korea. Contact between wild boars (Sus scrofa) and livestock or humans has steadily increased as wild boars venture down from the mountains to farms and residential areas. In this study, we examined the status and subtypes (STs) of Blastocystis in wild boars in South Korea and confirmed its zoonotic potential. From March 2016 to November 2018, we collected 433 fecal samples throughout the country from trapped or road-killed wild boars. The 18S rRNA gene was used for molecular identification and subtyping and the proportion of PCR-positive samples was 10.4%. We then assessed positive samples for associations with sex, region, and seasonal infection; however, no statistical significance was observed for any variable other than season. Phylogenetic analyses revealed that all sequences belonged to subtype 5 and had 99.5-99.9% identity with sequences obtained from Japanese cattle (Bos taurus) and 97.1% identity with sequences obtained from Chinese. Subtype 5 has been implicated in zoonoses, indicating that Korean wild boars could transmit Blastocystis to humans and other livestock. Our results, in accordance with the One Health concept, strongly support continued interest and efforts by public health and disease control organizations toward transmission prevention.