Cryptococcosis

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Sections available in full article Introduction, Presenting signs, Geographic incidence, Age predisposition, Pathogenesis, Etiology, Predisposing factors, Pathophysiology, Timecourse (incubation, duration), Epidemiology (population dynamics), Diagnosis, Presenting problems, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Standard treatment, Monitoring, Subsequent management, Prevention, Control, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications,
Contributors
Synonyms Cryptococcus neoformans disease

Introduction

  • Cause : Cryptococcus neoformans is a saprophytic yeast, widely distributed in nature; pigeon droppings are the most frequently reported source.
  • Organisms usually colonize upper respiratory tract.
  • Most common systemic fungal disease in cats (more common in cats than dogs).
  • Signs :
    • Four main clinical syndromes are respiratory (commonly associated with rhinitis/sinusitis).
    • Neurological.
    • Cutaneous.
    • Ocular.
  • Can become generally disseminated.
  • More common in cats with immunosuppression, eg feline leukemia virus (FeLV)  Feline leukemia virus  and feline immunodeficiency virus (FIV)  Feline immunodeficiency virus disease  .
  • Prognosis : generally good with treatment; more guarded if ocular or CNS involvement.
  • Treatment : antifungal therapy.

Diagnosis

Clinical signs

  • Chronic rhinitis.
  • Granulomatous dermatitis usually around nasal planum and skin over the bridge of the nose.
  • Depression.
  • Blindness.
  • Ataxia.
  • Paresis/paralysis.
  • Seizures.
  • Ocular discharge.
  • Optic neuritis.
  • Uveitis.
  • Retinal detachment.
  • Ulcerating dermal nodules.
  • Lymphadenopathy.
  • Bone pain.
  • Stertorous breathing (if dissemination to the lungs).

Diagnosis

Differential diagnosis

Chronic rhinitis
  • Viral upper respiratory infection, eg calicivirus  Feline calicivirus disease  , herpesvirus  Viral-induced upper respiratory tract disease  .
  • Foreign body.
  • Nasal polyps  Nasopharyngeal polyp  .
  • Neoplasia  Nasal cavity: neoplasia  .
Skin lesions
  • Bacterial  Bacterial skin disease: overview  .
  • Neoplasia  Skin: neoplasia  .
  • Other fungal infections, eg disseminated aspergillosis  Aspergillosis  .

Disseminated form

  • Toxoplasmosis  Toxoplasmosis  .
  • Lymphosarcoma  Lymphoma  .
  • FeLV infection  Feline leukemia virus  .
  • Feline infectious peritonitis (FIP)  Feline infectious peritonitis  .
  • Other systemic mycotic diseases, eg disseminated aspergillosis  Aspergillosis  , histoplasmosis .

Sequelae

Prognosis

Cutaneous/nasal cryptococcosis
  • Fair to good.

Ocular cryptococcosis

  • Poor.

Disseminated/CNS cryptococcosis

  • Grave.

Expected response to treatment

Over several weeks/months
  • Clinical resolution.
  • Culture negative.
  • Cytology negative.
  • Serum titer (LCAT) negative.

Reasons for treatment failure

  • Too severe.
  • Underlying immunosuppressive disease.
  • Cryptococcal meningoencephalitis.
  • Incorrect diagnosis.
  • Poor client compliance.
  • Incorrect therapy.
  • Therapy duration too short.

Sources

Publications

Other sources of information

  • Wolf A M and Troy G C (1995)Deep mycotic diseases.In:Textbook of Veterinary Internal Medicine.4th edn. Eds S J Ettinger and E C Feldman. Philadelphia: W B Saunders. p 439. (Good overall review, with feline bias.)
  • Ward D A (1995)Oculomycosis.In:Current Veterinary Therapy XII.Eds J D Bonagura and R W Kirk. Philadelphia: W B Saunders. p 1257. (Review of ocular cryptococcosis, together with other fungal diseases of mainly North American interest.)

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