Occurrence and Genetic Diversity of Trichomonas gallinae in Captive Synanthropic Birds in Southeastern Brazil.

Avian trichomonosis is caused by protozoa of the genus Trichomonas, mainly Trichomonas gallinae, which infects the upper digestive tract of birds and is commonly associated with Columbiformes, the main reservoirs of the parasite. This study aimed to investigate the occurrence and genetic diversity of Trichomonas spp. in captive synanthropic birds from southeastern Brazil. Oropharyngeal swabs were collected from 281 birds belonging to 13 avian orders and analyzed using Diamond medium culture, Giemsa-stained smears, and molecular assays. Of the 262 samples submitted to culture analysis, 72 (27.48%) showed trophozoite-like structures under light microscopy. Molecular screening based on the ITS1-5.8S-ITS2 region detected Trichomonas DNA in 76 out of 267 samples with successful DNA extraction (28.46%), including 72 Columba livia domestica from Franca, one Coragyps atratus from Ribeirão Preto, and three rock doves from Jaboticabal. Among the ITS-positive samples, 67 (88.15%) amplified the Fe-hydrogenase gene, and 65 (85.5%) were also positive for the 18S rRNA gene. Only six samples (2.29%) exhibited structures compatible with Trichomonas spp. in Giemsa-stained smears. Phylogenetic analyses based on ITS sequences grouped the isolates into two clades within the Trichomonas gallinae complex. Greater genetic diversity was observed using Fe-hydrogenase and 18S rRNA markers, revealing multiple haplotypes and clades. Molecular assays, particularly PCR applied directly to oropharyngeal swabs, showed higher sensitivity for detecting and characterizing Trichomonas gallinae compared to culture and cytology. These findings highlight the high occurrence and genetic diversity of T. gallinae in captive synanthropic pigeons and reinforce the importance of molecular tools for epidemiological surveillance in wildlife facilities.