Co-occurrence of Mycoplasma Species and Pigeon Herpesvirus-1 Infection in Racing Pigeons (Columba livia).
Key words: Mycoplasma, pigeon herpesvirus-1, the Netherlands, respiratory disease, avian, pigeon, Columba livia
Various infectious agents have been associated with respiratory disease in racing pigeons (Columba livia) and may severely compromise racing performance. (1,2) However, evidence demonstrating an etiologic relationship between the detected agents and the observed clinical signs of respiratory disease often is lacking. (3) Moreover, the presence of facilitating factors and importance of concurrent infection favoring the onset of respiratory disease in pigeons often are left unrevealed. (2)
Mycoplasma columbinum, M columborale, and M columbinasale have been isolated from the oropharynx, sinuses, air sac, lung, trachea, and eye in healthy pigeons as well as pigeons with respiratory disease. (3-11) Signs that have been attributed to clinical mycoplasmosis in pigeons include dyspnea, abnormal respiratory sounds, sneezing, conjunctivitis, and rhinitis. (3,4,9) Mycoplasma columbinum has been isolated from a racing pigeon with severe arthritis of the shoulder joint, (12) and M columbinum and M columbinasale have been isolated from the brain in pigeons. (3,6) However, definitive evidence for a primary pathogenic role of Mycoplasma species in pigeons is lacking. (2,3,7,10,13,14) While some investigators claim that virtually all pigeons are infected with mycoplasmas (15) and consider the pathogenicity of all mycoplasmas in pigeons to be negligible, (16) coinfection of pigeons with Mycoplasma species and other bacterial as well as viral agents is presumed to promote the onset or worsen the clinical manifestation of respiratory disease in pigeons. (17,18)
Worldwide, more than 50% of racing pigeons are deemed to be infected persistently with pigeon herpesvirus-1 (PHV-1). (18) Although clinical infection does not occur readily, high morbidity and variable mortality associated with PHV-1 infection may be observed when infected racing pigeons are exposed to facilitating factors, such as inadequate hygiene and environmental conditions, overcrowding, transportation, and high-intensity training. (18,19) Clinical disease resulting from PHV-1 infection seems to be observed most frequently during summer and the breeding season when large numbers of chicks are present. (18,20,21) While acute mortality is the most common sign of PHV-1 infection in juvenile pigeons, coryza, conjunctivitis, diphtheroid stomatitis, and pharyngitis are the most prominent signs observed in clinically affected subadult to adult pigeons with PHV-1 infections. (18,20,21) Concurrent or secondary bacterial infection may worsen the clinical course of PHV-1 infection in racing pigeons. (20,21)
We determined the prevalence of Mycoplasma species and PHV-1 infection in racing pigeons in the western part of the Netherlands. In addition, the potential synergistic effect of PHV-1 towards the development of respiratory disease in racing pigeons was investigated.
Materials and Methods
Animals and sampling
From the end of July 2013 through the end of March 2014, oropharyngeal swab samples were collected from 438 racing pigeons housed at 220 lofts in 3 Dutch provinces comprising the western part of the Netherlands (North-Holland, South-Holland, and Utrecht). The total number of pigeons lofts in the 3 provinces was estimated at 2000, so approximately 11% of the lofts in those provinces were included in the study. On average, two subadult to adult pigeons were sampled per loft. Samples were collected from 80, 217, and 141 pigeons housed at 41, 109, and 70 lofts in Utrecht, North-Holland, and South-Holland, respectively. Before sample collection, a clinical examination was performed on each pigeon to identify signs suggestive of respiratory infection, such as abnormal breathing sounds, rhinitis, nasal discharge, dyspnea, coryza, or pharyngitis. A questionnaire was completed for each sampled loft to ascertain whether any signs of respiratory disease had occurred during the 6-month period immediately before sampling in pigeons that did not have clinical respiratory disease at sampling. In pigeon lofts where signs of respiratory disease were present at sample collection, oropharyngeal swab samples were collected exclusively from pigeons with clinical respiratory disease. Pigeon lofts were categorized as positive for PHV-1 and Mycoplasma species (Table 1; H+/M+) if co-occurrence of both infections was demonstrated in a single pigeon or if both infections were detected separately in 2 individual pigeons housed in the same loft.
Polymerase chain reaction (PCR)
Extraction of DNA from swab samples was performed as described previously by Kempf et al. (22) For identification of Mycoplasma species a 16S rRNA gene-specific PCR was performed as described previously. (23) For species identification, PCR products were sequenced and sequences were compared to those maintained in the GenBank database through the Basic Local Alignment Search Tool (BLAST). For identification of PHV-1 in samples, a nested PCR was performed based on the protocol described by VanDevanter et al. (24) The potential of using both PCR protocols was explored as a proxy for shedding of PHV-1 and mycoplasmas in sampled pigeons.
Statistical analyses were performed to determine if the presence of Mycoplasma species was significantly associated with the presence of PHV-1 infection at the level of the entire study population of pigeons as well as at the level of pigeon lofts. In addition, we investigated whether infection with mycoplasmas, PHV-1, or the coinfection was associated with signs of respiratory disease. For this purpose, the infection status of the pigeons and pigeon lofts (4 categories based on the presence or absence of Mycoplasma species and/ or PHV-1) was related to the presence or absence of signs of respiratory disease (3 categories; no signs of respiratory disease at sample collection or during the 6-month period immediately before sampling, signs of respiratory disease within the 6-month period before sampling but not at sample collection, or signs of respiratory disease at sample collection; Table 1). These data were explored with simple descriptive and categorical statistical approaches. Categorical data analysis was performed using 2 X 2 contingency tables (%2 test) for which noninfected (H-/M-) pigeons or pigeon lofts with or without signs of respiratory disease were used as control groups. Furthermore, we investigated if the number of pigeons and pigeon lofts positive for Mycoplasma species and/or PHV-1 varied substantially among the 3 provinces. Due to the nonhomoscedasticity of the latter data, the nonparametric Friedman test was used. Levels of statistical significance were set at P < .05.
Prevalence of Mycoplasma species and PHV-1 infections in racing pigeons and pigeon lofts
A total of 174 of 438 sampled pigeons (39.7%) representing 120 of 220 pigeon lofts (54.5%) tested positive for Mycoplasma species, whereas 134 of 438 sampled pigeons (30.6%) belonging to 107 of 220 pigeon lofts (48.6%) tested positive for PHV-1. In 69 of 438 pigeons (15.8%) belonging to 59 of 220 pigeon lofts (26.8%), co-occurrence of Mycoplasma species and PHV-1 shedding was demonstrated (Table 1). Based on these results, the PCR protocols used appeared suitable as proxies for shedding of PHV-1 and mycoplasmas.
The number of pigeons and pigeon lofts positive for Mycoplasma species and/or PHV-1 was not significantly different among the 3 provinces (Friedman test, P > .05; Table 2). Mycoplasma columbinum, M columborale, and M columbinasale were detected in pigeons from each of the 3 provinces. Based on 16S rRNA gene sequencing, 8% of the Mycoplasma-positive samples could not be assigned to any of the latter species or other known Mycoplasma species and were categorized as such. Prevalence of M columbinum infection was the highest for each province (52.3%) followed by M columbinasale (28.2%) and M columborale (10.9%).
Association of PHV-1 and Mycoplasma species infection in racing pigeons with respiratory disease
In 60.5% of the sampled pigeon lofts, no pigeons showed signs of respiratory disease at the sample collection or during the prior 6 months. Physical signs of respiratory disease were identified in 8.6% of the lofts at sampling and in 30.9% during the 6 months before sampling. Table 1 shows the number of individual pigeons and pigeon lofts that tested positive for PHV-1 and/or Mycoplasma species in each of these categories.
Among entire study population, the association between shedding of PHV-1 and Mycoplasma species was not significant (Friedman test; P = .06). However, when examined at the level of pigeon flocks, coinfection with Mycoplasma species and PHV-1 was identified in more flocks than one of the infections alone (Table 1).
Among the entire study population and among the pigeon lofts, there was no significant correlation between the presence of Mycoplasma, PHV-1, or mixed infection and signs of respiratory disease at sampling or within the 6 months before oropharyngeal sampling ([chi square] test, 2 x 2 contingency tables).
Our results illustrated that Mycoplasma species and PHV-1 infection are commonly present in racing pigeons in the western part of the Netherlands. The relatively high number of Mycoplasmapositive pigeons was comparable to that reported for other countries. (3,4,8,9) As previously documented, the relative occurrence of different species of known mycoplasmas in pigeons seems to vary according to the investigated geographic region. (3,4) Mycoplasma columbinum was the most prevalent species in our study performed in the western part of the Netherlands.
Oropharyngeal sampling used to investigate the presence of Mycoplasma species and PHV-1 in our study was performed mainly during autumn and winter. Aside from climate variations, stressors, such as overcrowding, breeding, and participation in high-stakes pigeon races, may influence the number of PHV-1-positive pigeons detected by oropharyngeal sampling during certain seasonal periods. Especially for PHV-1, immunosuppression resulting from early coupling and breeding in the winter is considered an important facilitating factor promoting the onset of clinical herpesvirus infection in pigeons. (18) In addition to repetitive sampling of individual pigeons and pigeon lofts, continuous monitoring throughout the year to confirm seasonal variations and identify promoting factors is recommended.
When using oropharyngeal sampling, only pigeons that are excreting the tested agent(s) will be detected. Especially for PHV-1, latency and intermittent excretion are important characteristics. (18) Accordingly, repetitive oropharyngeal sampling of individual pigeons combined with serologic testing for PHV-1 and Mycoplasma species is necessary to estimate the overall prevalence of PHV-1 and Mycoplasma species in pigeon populations.
Although a trend toward significant co-occurrence of shedding of PHV-1 and mycoplasmas was demonstrated in the pigeon lofts, an etiologic relationship between the coinfection and the development of respiratory disease could not be demonstrated. Pathogenicity studies that focus on the 3 recognized Mycoplasma species in pigeons, the role of concurrent infections, and the presence of facilitating environmental factors may reveal the importance of mycoplasmas in inducing respiratory disease in racing pigeons.
(1.) Rupiper DJ. Diseases that affect race performance of homing pigeons. Part II: Bacterial, fungal, and parasitic diseases. J Avian Med Surg. 1998; 12(3): 138-148.
(2.) Esposito JF. Respiratory medicine in pigeons. Vet Clin North Am Exot Anim Pract. 2000:3(2):395 402.
(3.) Keymer IF, Feach RH, Clarke RA, et al. Isolation of Mycoplasma spp. from racing pigeons (Columba livia). Avian Pathol. 1984; 13(1):65 74.
(4.) Shimizu T, Erno H, Nagatomo H. Isolation and characterization of Mycoplasma columbinum and Mycoplasma columborale, two new species from pigeons. Int J Syst Bacteriol. 1978;28(4):538-546.
(5.) Sinclair DV. Respiratory disease in pigeons. Vet Rec. 1980;l06(22):466-467.
(6.) Jordan FT, Howse JN, Adams MP, Fatunmbi OO. The isolation of Mycoplasma columbinum and M. columborale from feral pigeons. Vet Rec. 1981; 109(20):450.
(7.) MacOwan KJ, Jones HG, Randall CJ, Jordan FTW. Mycoplasma columborale in a respiratory condition of pigeons and experimental air sacculitis of chickens. Vet Rec. 1981; 109(25-26):562.
(8.) Chiocco D. Bisceglia ED. Isolation of mycoplasmas from the oropharynx of clinically healthy pigeons. Selezione Veterin. 1990:31 (5):583 586.
(9.) Nagatomo H, Rato H, Shimizu T, Katayama B. Isolation of mycoplasmas from fantail pigeons. J Vet Med Sci. 1997;59(6):461 462.
(10.) Loria GR, Tamburello A, Figa F, et al. Isolation of mycoplasmas from pigeons suffering eye lesions and respiratory disease. Vet Rec. 2005:157(21):664-665.
(11.) Turcsanyi I, Bistyak A, Matiz K, et al. Isolation of Mycoplasma columbinasale from pigeons in Hungary. Vet Rec. 2005; 157(8):235-236.
(12.) Hellebuyck T, Garmyn A, De Cooman L, et al. Mycoplasma columbinum isolated from a racing pigeon (Columba livia) with arthritis. J Avian Med Surg. 2014;28(3):240-241.
(13.) Pettersson B, Tully JG. Bolske G, Johansson K-E. Re-evaluation of the classical Mycoplasma lipopliilum cluster (Weisburg et al. 1989) and description of two new clusters in the hominis group based on 16S rDNA sequences. Int J Syst Evol Microbiol. 2001; 51(Pt 2):633-643.
(14.) Molokwu JU, Adegboye DS. Mycoplasma columborale and Mycoplasma columbinum from pigeons: a first report of their isolation in Nigeria. Rev Sci Tech Off Int Epizoot. 1988;7(3):635-638.
(15.) Schrag L, Enz H, Klette H. Healthy pigeons. Recognition, prevention and treatment of major pigeon diseases. In: Schober VF. Healthy Pigeons (Recognition, Prevention and Treatment of the Major Pigeon Diseases), 11th ed. Hengersberg, Germany: Verag L. Schober; 1977:57-72.
(16.) Gerlach H. Ober das vorkommen von Mykoplasmen bei Tauben. Berl Munch Tierdrtzl Wochenschr 1977:90(7): 140-143.
(17.) Cornwell HJC, Wright NG. Herpesvirus infection of pigeons. I. Pathology and virus isolation. J Comp Pathol. 1970;80(2):221-226.
(18.) Vindevogel H, Debruyne H, Pastorett PP. Observation of pigeon herpesvirus 1 re-excretion during the reproduction period in conventionally reared homing pigeons. J Comp Pathol. 1985;95(1): 105-112.
(19.) Marlier D, Vindevogel H. Viral infections in pigeons. Vet J. 2006;172(1):40-51.
(20.) Vindevogel, H, Pastoret PP. Pigeon herpes infection: natural transmission of the disease. J Comp Pathol. 1980;90(3):409-413.
(21.) Vindevogel H, Pastoret PP. Pathogenesis of pigeon herpes infection. J Comp Pathol. 1981;91 (3):415 426.
(22.) Kempf I. Blanchard A, Gesbert F, et al. The polymerase chain reaction for Mycoplasma gallisepticum detection. Avian Pathol. 1993;22(4):739-750.
(23.) Kiss I, Matiz K, Kaszanyitzky E. et al. Detection and identification of avian mycoplasmas by polymerase chain reaction and restriction fragment length polymorphism assay. Vet Microbiol. 1997; 58(l):23-30.
(24.) VanDevanter DR, Warrener P, Bennett L, et al. Detection and analysis of diverse herpesviral species by consensus primer PCR. J Clin Microbiol. 1996; 34(7):1666-1671.
Tom Hellebuyck, DVM, PhD, Stephan Gobel, DVM, Frank Pasmans, DVM, PhD, Connie Adriaensen, PhD, and An Martel, DVM, PhD
From the Department of Pathology. Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Table 1. Prevalence of Mycoplasma species and-or PHV-1 infection, as tested by PCR on oropharyngeal swab samples, in pigeon lofts and racing pigeons with or without respiratory signs in 3 provinces in the western part of the Netherlands. N PHV1+/M- Pigeon Pigeon Pigeons, Presence of lofts Pigeons lofts, % % respiratory signs Absent at sampling/ 133 266 12.7 13.2 absent during 6 mos before sampling Absent at sampling/ 68 135 17.6 17.7 present during 6 mos before sampling Present at sampling 19 37 15.8 16.2 Total 220 438 14.6 14.8 PHVI-/M+ PHV1+/M+ Pigeon Pigeons Pigeon Pigeons, Presence of lofts, % % lofts, % % respiratory signs Absent at sampling/ 22.6 24.4 31.6 15.8 absent during 6 mos before sampling Absent at sampling/ 19.2 24.4 38.2 16.3 present during 6 mos before sampling Present at sampling 15.8 18.9 31.6 13.5 Total 20.3 24.0 26.8 15.8 PHV1-/M- Pigeon Pigeons, Presence of lofts. % % respiratory signs Absent at sampling/ 33.1 46.6 absent during 6 mos before sampling Absent at sampling/ 25.0 41.5 present during 6 mos before sampling Present at sampling 36.8 51.4 Total 38.3 45.4 Abbreviations: PVH-1 or PHV1, pigeon herpesvirus-1; M. Mycoplasma species: PCR, polymerase chain reaction. Table 2. Prevalence of Mycoplasma species and/or PHV-1 infection, as tested by PCR on oropharyngeal swab samples, in pigeon lofts and racing pigeons by province in the western part of the Netherlands. N PHV1+/M- Pigeon Pigeon Province lofts Pigeons lofts, % Pigeons, % Utrecht 41 80 56.2 42.5 North-Holland 109 217 42.8 26.2 South-Holland 70 141 48.6 29.0 Total 220 438 14.6 14.8 PHV1-/M+ PHV1+/M + Pigeon Pigeon Province lofts, % Pigeons, % lofts, % Pigeons, % Utrecht 53.7 41.3 34.2 13.8 North-Holland 44.2 31.2 25.7 19.1 South-Holland 44.7 44.7 39.4 14.3 Total 20.3 24.0 26.8 15.8 Abbreviations: PVH-I or PHV1. pigeon herpesvirus-1; M, Mycoplasma species; PCR, polymerase chain reaction.
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Research Brief|
|Author:||Hellebuyck, Tom; Gobel, Stephan; Pasmans, Frank; Adriaensen, Connie; Martel, An|
|Publication:||Journal of Avian Medicine and Surgery|
|Date:||Dec 1, 2017|
|Previous Article:||The Incidence and Treatment Outcomes of Macrorhabdus ornithogaster Infection in Budgerigars (Melopsittacus undulatus) in a Veterinary Clinic.|
|Next Article:||Acute, Fatal, Presumptive Xylitol Toxicosis in Cape Sugarbirds (Promerops cafer).|