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Trichomonosis in wild birds: etiological, molecular and histopathological aspects


Avian trichomoniasis, caused by the flagellate protozoan Trichomonas gallinae, is a disease that mainly affects the upper digestive tract of birds. The main natural hosts of this agent are birds of the order Columbiformes, Falconiformes and Strigiformes. Oral lesions, obstructing the digestive and upper respiratory tracts, caused feeding, and breathing difficulty and often cause death by hunger, dehydration, and asphyxia/apnea. A more detailed study of trichomoniasis in birds is justified, as the pathogenicity of the etiologic agent is varied. Clinical/necroscopic conditions are observed, ranging from asymptomatic to very severe. Locally necrotic lesions are observed in the oropharyngeal region, esophagus and crop. Congestion and fibrinous lesions in the liver, lungs and tongue, occurs, resulting in high mortality. Also, a well-defined differential diagnosis is important, since there are other etiological agents that can cause illness with similar clinical presentations. This study aims to investigate the occurrence and genetic diversity of trichomonads in different species of wild birds in Brazil. Also are the objective to investigate the possible association between parasite genotype, bird species and the lesions' severity. For this study, biological samples of wild and captive birds belonging to taxonomic groups of the order Accipritiformes, Anseriformes, Columbiformes, Falconiformes, Gruiformes, Passeriformes, Piciformes, Psittaciformes, Strigiformes will be analyzed. Samples of live birds from captivity (zoos, veterinary clinics, and wild animal rescue center) and free-living birds will be analyzed, as well as dead birds sent for necropsy. From live captive birds, samples of oropharyngeal and crop mucosa smears will be collected using swab and destined for culture in InPouch TF medium, followed by DNA extraction and molecular assays for trichomonads. From live birds captured in the Pantanal, oropharyngeal mucosa smears samples will be collected for molecular technique (PCR). From the birds sent for necropsy, tissue samples will be collected for histological evaluation and PCR for the agents under study. The molecular assays will target gene fragments from the ITS1-5.8S-ITS-2 intergenic region, ±-tubulin and Fe-hydrogenase. The sequences obtained will be submitted to phylogenetic and genotypic diversity analysis. This study will contribute to the understanding of the genetic diversity of trichomonads in wild Brazilian birds and the host-parasite relationship. (AU)

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