Respiratory Fungal Infections - Pathology
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Blastomycosis
- Caused by Blastomyces dermatitidis
- Occurs mainly in the Americas, Middle East and Africa, occasionally in Europe
- Mainly in young dogs, occasionally other species
- Can involve almost any tissue after spread from lungs
- Gross lesions:
- Microscopic lesions:
- Yeast fungi with thich walls in nodules with macrophages, neutrophils and giant cells
Histoplasmosis
- Caused by Histoplasma capsulatum
- Gross lesions in lungs:
- Firm encapsulated granulomas (granulomatous pneumonia)
- Microscopic lesions:
- Macrophages with inracytoplasmic yeasts
- Also in other tissues
Pneumocystis carinii
- Important cause of pneumonia in humans associated with immunodeficiency states
- It has been occasionally reported in young or immunosuppressed animals (e.g. Arabian foals with congenital immunodeficiency)
- Grossly:
- Diffuse interstitial pneumonia
- Patches of firmness or consolidation
- Histologically:
- Alveoli are filled with pale staining acidophilic material (= trophozoite and cyst forms of the organism)
- It is thought that as P. carinii is often present as a latent infection, alveolar macrophages normally control the organism - a process which fails in immunodeficient states