Molecular Detection and Genotyping of <i>Blastocystis</i> in Farmed Minks and Raccoon Dogs in Northern China

<i>Blastocystis</i> is a common intestinal protozoan found in both humans and animals. However, research on <i>Blastocystis</i> infections in minks (<i>Neovison vison</i>) and raccoon dogs (<i>Nyctereutes procyonoides</i>) is limited. This study aimed to investigate the prevalence and subtypes of <i>Blastocystis</i> in these two species across northern provinces of China using small subunit rRNA gene sequence analysis. We examined 275 minks (89 from Hebei Province, 57 from Heilongjiang Province, 109 from Liaoning Province, and 20 from Shandong Province) and 235 raccoon dogs (114 from Hebei Province, 27 from Heilongjiang Province, 61 from Liaoning Province, and 33 from Jilin Province). The overall infection rate was 13.5% (69/510). Farmed minks had a prevalence of 1.5% (4/275), while raccoon dogs showed a significantly higher prevalence of 27.7% (65/235). We identified five distinct subtypes (ST1, ST2, ST3, ST5, and potentially novel subtype) across both species: ST1 (15 cases), ST2 (15 cases), ST3 (31 cases), ST5 (7 cases), and potentially novel subtype (1 case). This study is the first to report ST1 and ST3 in minks and ST1, ST2, ST5, and potentially novel subtype in raccoon dogs. As ST1, ST2, ST3, and ST5 subtypes are also found in humans, our findings suggest that minks and raccoon dogs may serve as potential reservoirs for human <i>Blastocystis</i> infections. Furthermore, the newly identified, potentially novel subtype might also be transmissible to humans or other animals. This research enhances our understanding of <i>Blastocystis</i> distribution among hosts in China and supports zoonotic disease prevention efforts related to farmed minks and raccoon dogs.