Felis ISSN 2398-2950

Respiratory fungal disease

Synonym(s): Aspergillus, Cryptococcosis, Histoplasmosis, Blastomycosis, Coccidioidomycosis, Pheohyphomycosis

Contributor(s): Rhea Morgan, Elizabeth Rozanski

Introduction

Pathogenesis

Etiology

  • Aspergillus spp:
    • Aspergillus fumigatus.
    • Aspergillus terreus.
    • Aspergillus deflectus.
    • Aspergillus flavipes.
    • Aspergillus niger.
    • Aspergillus nidulans.
    • Aspergillus flavus.
  • Blastomyces dermatitidis.
  • Coccidioides immitis.
  • Histoplasma capsulatum.
  • Cryptococcus neoformans.
  • Rhinosporidium seeberi
  • Phaeohyphomycosis: dematiaceous fungi.

Predisposing factors

General

  • Access to source of spores - usually external environment, soil, bird (especially pigeon) guano.
  • Immunosuppression from feline leukemia virus, feline immunodeficiency virus, etc.
  • Prior treatment with corticosteroids.

Coccidiomycosis

  • Hot dry summer months encourages inhalation of spores via dust.
  • Cats are fairly resistant to this disease. Many exposed cats develop only transient respiratory signs.

Cryptococcosis

  • Cryptococcus neoformans var. gattii- access to eucalyptus trees when shedding bark (organism carried in bark).
  • Cryptococcus  neoformans var. neoformans - access to soil rich in pigeon droppings.
  • Most common systemic fungal infection in cats.

Blastomycosis

  • Access to organism in soil.
  • Cats are more resistant to this disease than are dogs.

Histoplasmosis

  • Access to organism in soil rich in bird or bat guano.
  • Disease is more common in cats than in dogs.
  • Many cats are exposed, but do not develop overt clinical disease.

Aspergillosis

  • Inhalation of spores causes focal nasal infections in most affected cats.
  • Inhalation of spores in immunosuppressed cats may result in disseminated disease.

Rhinosporidiosis

  • Often requires contact with standing or stagnant water
  • Rare disease in cats.

Pathophysiology

  • Environmental exposure    →   inhalation    →   localization in respiratory tissue    →   wider dissemination in body (variable).
  • Fungal agent    →   inhaled    →   either:
    • Localized, mild, subclinical infection.
    • Local spread in nasal and facial tissue.
    • Severe pulmonary disease.
    • Systemic infection.

Timecourse

Blastomycosis

  • 5-12 weeks.

Coccidiomycosis

  • Weeks to years.

Others

  • Several weeks

Epidemiology

  • See individual microorganisms.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Tennant K, Patterson-Kane J, Boag A K et al (2004) Nasal mycosis in two cats caused by Alternaria species. Vet Rec 155 (12), 368-370 PubMed.


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