Prevalence and genotyping of Trichomonas gallinae in pigeons and birds of prey

Abstract

Avian trichomonosis is a world-wide parasitic disease caused by the protozoan Trichomonas gallinae. Although several degrees of pathogenicity have been described on the basis of the clinical signs in birds, there are few reports concerning the genetic characterization of the parasite and its relationship with pathogenicity. The parasite usually appears apathogenic but is occasionally responsible for outbreaks of the disease in avian populations, particularly affecting nestlings of ornithophagous raptors. For 3 years, cultures of oropharingeal samples from 612 wild and domestic pigeons (Columba livia) and 102 birds of prey from 15 different species were made in an attempt to determine the prevalence of T. gallinae in the Valencian Community (eastern Spain). To establish the genotype of the isolates, 5.8S rRNA and the surrounding internal transcribed spacer regions were amplified by polymerase chain reaction and were sequenced. After restriction map analysis, sequencing and polymerase chain reaction-restriction fragment length polymorphism using HaeIII showed two genotypes (A and B) in isolates from both groups of birds, although genotype prevalence differed in each group—genotype A being more prevalent in columbiforms and genotype B in raptors. In addition, genotype B was present in every bird that displayed macroscopic lesions.