Molecular Survey and Genetic Characterization of Tetratrichomonas buttreyi and Pentatrichomonas hominis in Horses in Shanxi Province, Northern China.

Trichomonads include species of veterinary and zoonotic importance, yet infections with trichomonads in horses remain uncharacterized in Shanxi Province, Northern China. In the present study, we conducted a molecular survey of Tetratrichomonas buttreyi and Pentatrichomonas hominis using 631 horse fecal samples collected from Datong, Taiyuan, and Yuncheng cities in Shanxi Province between March and June 2023. Nested PCR assays targeting the small subunit ribosomal RNA (SSU rRNA) gene were used to detect the two trichomonad species. The overall molecular prevalences were 3.7% (23/631; 95% CI, 2.5-5.5%) for T. buttreyi and 0.8% (5/631; 95% CI, 0.3-1.9%) for P. hominis. T. buttreyi prevalence differed significantly by region and management mode but not by age or sex. P. hominis was detected only in Datong City, resulting in a significant regional difference; however, age, sex, and management mode were not significantly associated with P. hominis prevalence. Five representative T. buttreyi sequences and one representative P. hominis sequence were obtained in the present study. Among these sequences, two T. buttreyi sequences shared 100% nucleotide identity with reference sequences from pigs, cattle, and horses; three showed only minor nucleotide variation. The representative P. hominis sequence clustered with the zoonotic genotype CC1, suggesting that horses may form part of the broader host network of P. hominis, though further work is needed to establish horses' reservoir competence or confirm their role in the transmission. These findings provide the first molecular evidence of T. buttreyi and P. hominis in horses from Shanxi Province, and establish a baseline for future surveillance and One Health risk assessments.