Epidemiological investigation of Blastocystis in dairy cattle in Xinjiang, China: Unusual detection of avian-adapted subtype ST7.

Blastocystis is a common anaerobic intestinal protist with a broad host range, including humans and various animals. In this study, a total of 907 fecal samples were collected from dairy cattle across six large-scale farms in Xinjiang and screened for the presence of Blastocystis by PCR targeting the small-subunit ribosomal RNA (SSU rRNA) gene. The overall infection rate was 18.1% (164/907), with significant variation among farms (1.4%-29.6%) and age groups (12.1%-20.8%). Ten subtypes of Blastocystis were identified: ST1 (n = 6), ST5 (n = 14), ST7 (n = 13), ST10 (n = 18), ST14 (n = 7), ST21 (n = 6), ST24 (n = 11), ST25 (n = 14), ST26 (n = 25), and ST42 (n = 50). Genetic analysis revealed 15 haplotypes with high nucleotide diversity (34.14% of the nucleotide sites were polymorphic). Notably, the avian-adapted subtype ST7 was the predominant subtype in cattle in Hutubi county, and phylogenetic reconstruction confirmed the distinct clustering of ST7 with avian-derived sequences. This study provides a comprehensive insight into Blastocystis infection in dairy cattle in Xinjiang, highlighting unusual ST7 presentation and underscoring the role of cattle as a reservoir for diverse Blastocystis subtypes in this region.