Laboratory investigations into the origin of Mycoplasma synoviae isolated from a lesser flamingo (Phoeniconaias minor)

Abstract

Background: The role of wild birds in the transmission and spread of mycoplasmas is not clear. Up to now different Mycoplasma species have been isolated from wild birds many of which are not considered pathogens sensu stricto for domestic flocks. This report describes the first isolation of Mycoplasma synoviae in a captive lesser flamingo (Phoeniconaias minor) held in a zoo in Italy and the laboratory investigations performed to elucidate its origin. Results showed that the strain was similar to the MS-H vaccine strain using the vlhA methods although no vaccination with this product was used in the zoo.

Case presentation: This paper describes investigations into a case in which 10 of 12 adult lesser flamingos (Phoeniconaias minor) died after having recently been moved from the Netherlands to a new zoo in Northern Italy. While most of the birds appeared to have died from the stress of movement and poor adaptation to their new environment, Mycoplasma synoviae, an important poultry pathogen in the layer and meat industry, was isolated for the first time from the trachea of one animal presenting catarrhal tracheitis and fibrinous airsacculitis. Genetic analysis of the conserved region of the vlhA was not able to differentiate the flamingo strain from the MS-H vaccine strain. However differences in the sequences of the obg gene of the flamingo and vaccine strain were detected. A test for temperature-sensitivity (ts) gave a ts (-) phenotype for the flamingo strain, in contrast to the ts (+) status of the MS-H strain. Based on this information and knowing that the flamingos were not vaccinated against M. synoviae, it is highly likely that the flamingo was infected with a genetically similar wild strain by contact with infected birds.

Conclusions: This case provides evidence for the potential role of international trade of ornamental birds as a possible route of introduction of new mycoplasma strains between countries, and moreover highlight that vlhA gene sequencing was not sufficient to discriminate the wild strain isolated from the flamingo from the MS-H vaccine strain.

Keywords: Aereosacculitis; Lesser flamingo; Mycoplasma synoviae; Phoeniconaias minor; VlhA.

Fig. 1

Gross pathology findings. Fibrinous airsacculitis in bird #2

Fig. 2

DGGE gel. In the lanes 1, 2 and 3 there are Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma meleagridis controls respectively. From lane 5 to 10 there are diagnostic samples positive for Mycoplasma synoviae: in lane 5 Mycoplasma synoviae NCTC (reference strain) and in lane 6 the strain isolated from flamingo (HG421742.1 IZSVE/2010/5711)

Fig. 3

Histopathology findings. The cervical air sac is severely expanded by a focal nodular lesion composed of abundant heterophils partially surrounded by a single to double layer of macrophages and occasional multinucleated giant cells (heterophilic granuloma), the remaining tissue is diffusely enlarged by strong fibroplasia and moderate lymphoplasmacytic infiltration

Fig. 4

Phylogenetic analysis of the vlhA gene. Basing on the vlhA gene, the flamingo isolate (HG421742.1 IZSVE/2010/5711) clusters with the MS-H vaccine strain (AB501271) and the Australian isolate DQ661614. They are all classified as type C - subtype three by Bencina et al. [26] and group 13 by Hammond et al. [19]. The strains FN666087.1 and B91/96/798 are classified as type C3 - group 5; the strain B11/85 is a C1 – group 4. The strains FN666087.1, B91/96/798 and B11/85 have been introduced as examples of different genotypes to build the phylogenetic tree