Mycoplasma columbinum Isolated From a Racing Pigeon ( Columba livia ) With Arthritis

Detection of Mycoplasma columbinasale in Cases of Respiratory Disease in Domestic Pigeons (Columba livia var. domestica)

In 2017, respiratory disease and low mortality were reported in domestic flying pigeons (Columba livia var. domestica) trained as hunting live bait in a breeding farm in Umbria, Italy. Clinically, open beak breathing, dropped wings, and pharyngeal and laryngeal hyperaemia were observed. Three birds were submitted for necropsy. Gross pathological evaluation revealed in all cases diffuses hyperaemia of the tracheal mucosa in association with mild emaciation and multiorgan congestion. Microscopically, diffuse epithelial hyperplasia of the trachea ( $n=3$ ) and diffuse lymphocytic infiltration of the lamina propria ( $n=3$ ) were observed. No lesions were reported in other organs. Based on reported clinical signs and lesions, Mycoplasma spp. were suspected, and molecular detection was performed on tracheal specimens leading to the identification of Mycoplasma columbinasale. Immunohistochemistry was subsequently performed to localize the microorganism within tissue lesions. Immunohistochemistry confirmed the presence of Mycoplasma species on the tracheal epithelial cells of all birds. Following tylosin administration, complete resolution of the clinical condition and lack of recurrence of clinical signs were reported in the breeding farm. These findings suggest that M. columbinasale could potentially have a role in the respiratory disease and low mortality in domestic pigeons.

Occurrence and Relevance of Mycoplasma spp. in Racing and Ornamental Pigeons in Poland

This report is one of the first studies describing the relationship between the occurrence of Mycoplasma spp. as regards the type of breed and health status of pigeons. The aim of the study was to evaluate the prevalence of Mycoplasma gallisepticum, Mycoplasma synoviae, Mycoplasma columbinum, Mycoplasma columborale, and Mycoplasma columbinasale in Polish populations of racing and ornamental pigeons in the context of their correlation with type of breed and health status. The study was conducted on 179 samples (100 racing and 79 ornamental pigeons) collected from pigeons in different regions of Poland. Tracheal swabs were examined for Mycoplasma spp. using genus-specific PCR. If Mycoplasma spp. were detected, the species were identified by species-specific PCR developed on the 16-23S rRNA intergenic spacer region. Ninety-two of 100 (92%) racing pigeons and 67 of 79 (85%) ornamental pigeons were Mycoplasma spp. positive. None of the tested pigeons were positive for M. gallisetpticum or M. synoviae. The average prevalence of M. columbinum was determined at 49%, M. columborale at 79%, and M. columbinasale at 23% in all birds tested. A single mycoplasma infection was found in 40% of pigeons whereas multiple infections were found in 49% of tested birds. Differences were found in the occurrence of mycoplasmas between racing and ornamental pigeons. Our results have shown a high prevalence of Mycoplasma species both as a single and as multiple infections.

Co-occurrence of Mycoplasma Species and Pigeon Herpesvirus-1 Infection in Racing Pigeons ( Columba livia)

Oropharyngeal swab samples were collected from 438 live racing pigeons ( Columba livia), with and without signs of respiratory disease, that were housed in 220 lofts in 3 provinces in the western part of the Netherlands. Polymerase chain reaction (PCR) was used to identify Mycoplasma species and pigeon herpesvirus-1 (PHV-1) from the samples. In 8.6% of the pigeon lofts tested, signs of respiratory disease were present in pigeons at sampling, and in 30.9% of the sampled pigeon lofts, respiratory signs were observed in pigeons during the 6-month period immediately before sampling. A total of 39.8% of tested pigeons (54.5% of tested lofts) were positive for Mycoplasma species, and 30.6% of tested pigeons (48.6% of tested lofts) were positive for PHV-1. In 15.8% of the tested pigeons (26.8% of tested pigeon lofts), coinfection by Mycoplasma species and PHV-1 was identified. The number of pigeon lofts having pigeons coinfected by Mycoplasma species and PHV-1 was higher than that where only one of the infections was identified. Neither the presence of Mycoplasma species, PHV-1, nor the co-occurrence of both infections was significantly associated with signs of respiratory disease.

Galliformes and Columbiformes

Galliformes and columbifomes are closely associated with humans and some species have been domesticated for well over 5000 years. Both orders remain diverse, ranging from the common domestic poultry species (e.g., chicken, turkey, and squabs) to the more exotic species found in the wild and in zoological collections. While many species have been benefited from human activities and have increased their ranges, others have declined in numbers and some have become threatened (e.g., Trinidad piping-guan and wood quail) or even extinct (e.g., dodo and passenger pigeon). Nondomestic galliformes and columbiformes are susceptible to many of the same diseases that occur in domestic species, yet predisposition may be different. Furthermore, disease prevalence depends on exposure and potential risk factors. Infectious diseases that tend to be more common under intensive commercial production may not pose as great a risk to exotic and free-living species.