Mycoplasmosis in ferrets

Abstract

We report an outbreak of severe respiratory disease associated with a novel Mycoplasma species in ferrets. During 2009-2012, a respiratory disease characterized by nonproductive coughing affected ≈8,000 ferrets, 6-8 weeks of age, which had been imported from a breeding facility in Canada. Almost 95% became ill, but almost none died. Treatments temporarily decreased all clinical signs except cough. Postmortem examinations of euthanized ferrets revealed bronchointerstitial pneumonia with prominent hyperplasia of bronchiole-associated lymphoid tissue. Immunohistochemical analysis with polyclonal antibody against Mycoplasma bovis demonstrated intense staining along the bronchiolar brush border. Bronchoalveolar lavage samples from 12 affected ferrets yielded fast-growing, glucose-fermenting mycoplasmas. Nucleic acid sequence analysis of PCR-derived amplicons from portions of the 16S rDNA and RNA polymerase B genes failed to identify the mycoplasmas but showed that they were most similar to M. molare and M. lagogenitalium. These findings indicate a causal association between the novel Mycoplasma species and the newly recognized pulmonary disease.

Video

Ferret with mycoplasmosis, coughing. This video is 26 seconds in length, with audio.

Figure 1

Lateral radiographic view of the thorax from a 2-year-old ferret with cough and labored breathing, showing a bronchointerstitial pattern with peribronchial cuffing.

Figure 2

Lungs from a 2-year-old ferret that died of acute dyspnea, showing multifocal, tan to gray semifirm nodules centered on airways and severely narrowed lumina of affected airways.

Figure 3

Micrographs of a section of lung from a 2-year-old ferret that died of acute dyspnea. A) Image shows moderate bronchointerstitial pneumonia with severe hyperplasia of bronchiole-associated lymphoid tissue around a narrowed airway lumen; original magnification ×40. B) Immunohistochemical analysis conducted with antibodies against mycoplasmas demonstrates intense labeling along the apical border of the ciliated respiratory epithelium; original magnification ×40. C) Confocal scanning laser microscopy conducted with antibodies against mycoplasmas demonstrates intense fluorescent labeling along the brush border of the bronchial epithelial cells; original magnification ×40.

Figure 4

Transmission electron micrograph of the lung from a 2-year-old ferret that died of acute dyspnea, showing loss of cilia in bronchial epithelial and cellular degeneration characterized by swelling of endoplasmatic reticulum, vacuolization of mitochondria with loss of christae, and intranuclear chromatin dispersion. Attached to the apical surface of a ciliated cell is a 0.8-μm pleomorphic mycoplasma-like organism (arrow). Scale bar = 0.5 µm.

Figure 5

Scanning electron micrographs of the lung from a 2-year-old ferret that died of acute dyspnea, showing A) marked loss of cilia with multifocal degenerative changes characterized by bulbous swelling of cilia (arrows) and necrosis of bronchial epithelial cells (N) (scale bar = 1 µm); B) marked loss of cilia and numerous pleomorphic mycoplasma-like organisms diffusely attached to the mucosal surface (arrow) (scale bar = 1.25 µm); C) focal area of cilia loss and cell membrane damage with mycoplasma-like organisms (arrow) at the periphery of the lesion (scale bar = 400 nm); and D) many mycoplasma-like organisms (arrow) covering ciliated bronchial epithelial cells (scale bar = 2 µm).

Figure 6

Phylogenetic analysis of A) partial 16S rDNA gene (933 bp) and B) partial RNA polymerase B gene (733 bp) for the new mycoplasma isolates and other closely related Mycoplasma species as conducted in MEGA4 (13). The bootstrap consensus phylogenetic trees were constructed by using the neighbor-joining method (14). The bootstrap values as shown above the branches were inferred from 1,000 replicates of data resampling to represent the evolutionary distances of the species analyzed (15). The tree is drawn to scale; branch lengths are in the same units as those of the evolutionary distances used to infer the phylogenetic tree (i.e., the units of the number of base substitutions per site).