First detection and molecular characterization of three trichomonad species in experimental beagle dogs in China

Three different parasites of the phylum Parabasalia (Pentatrichomonas hominis, Tritrichomonas foetus and Dientamoeba fragilis) have been described in dogs. However, limited information about the prevalence of these trichomonad species in experimental beagle dogs in China is available. The aim of the current study was to investigate the frequency and molecular characterization of these three parasites species in these dogs. A total of 452 fecal samples were collected from ordinary clean-grade experimental beagle dogs and examined using PCR analysis, and positive samples were subsequently sequenced for species identification and analysis. Results showed that the prevalence of P. hominis, T. foetus and D. fragilis in the experimental dogs was 6.4% (29/452, 95% CI: 4.1-8.7%), 0% (0/452) and 0.7% (3/452, 95% CI: 0-1.4%), respectively. The sequence and phylogenetic analyses showed that the obtained sequences of P. hominis SSU rRNA genes were similar to the previously reported genotype CC1, and the sequences of D. fragilis SSU rRNA genes belonged to genotype 1, which is the most common genotype in humans. Our study provides the first data on the molecular prevalence of P. hominis, T. foetus and D. fragilis in experimental beagle dogs globally.