Canis ISSN: 2398-2942

Cryptococcus neoformans

Synonym(s): C. neoformans

Contributor(s): Rosanna Marsella

Introduction

Classification

Taxonomy

  • Genus: Cryptococcus - a genus of yeast-like fungi. (Strains have been experimentally converted to a mycelial, sexually reproducing phase and given the name Filobasidiella neoformans.)

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Clinical Effects

Epidemiology

Habitat

  • Lives in soil and dust.

Lifecycle

  • Can affect any mammal, but cats are at higher risk for it.
  • No immunosuppression is usually detected in cats with cryptococcosis, eg FeLV, FIV.
  • Pigeons often carry the agent but are rarely affected clinically - temperature too high for growth of agent.

Transmission

  • Respiratory, occasionally percutaneous by direct inoculation of the organism.
  • Non-contagious.

Pathological effects

  • Human infection often associated with pre-existing immunosuppression.
  • Virulence is largely associated with the antiphagocytic and immunosuppressive capsule.
  • Route of infection: usually respiratory, resulting in lesions in nasal cavity or sinuses with possible extension to the brain (involvement of the optic nerve causing blindness), and meninges.
  • Cattle: mastitis, with severe swelling and rarely may spread to lungs. Infection may be introduced during intramammary medication.
  • Horses: nasal passage granulomata.
  • Dogs: granulomata of subcutaneous tissue, with possible central nervous system (CNS) and ocular signs including.
  • Cats: granulomata of subcutaneous tissue, with respiratory signs.
  • Human beings: respiratory disease and meningitis.

Control

Control via chemotherapies

  • Amphotericin B Amphotericin B (used initially for rapid efficacy combined later on with aerodes, eg flucytosine (orally) Flucytosine ).
  • Fluconazole Fluconazole - drug of choice if neurological involvement is present due to excellent penetration in the brain. Used orally at 2.5-5 mg/kg once daily for several months. Dosage should be reduced in patients with compromised renal function.

Control via environment

  • Avoid areas contaminated with pigeon droppings.

Vaccination

  • Not available.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Malik R, Speed B R, Kaldor J et al (1999) Serum antibody response to Cryptococcus neoformans in cats, dogs and koalas with and without active infection. Med Mycol 37 (1), 43-51 PubMed.
  • Malik R, Hunt G B, Bellenger C R et al (1999) Intra-abdominal cryptococcosis in two dogs. JSAP 40 (8), 387-391 PubMed.
  • Tiches D, Vite C H, Dayrell-Hart B et al (1998) A case of canine central nervous system cryptococcosis - management with fluconazole. JAAHA 34 (2), 145-151 PubMed.
  • Malik R, McPetrie R, Wigney D I et al (1996) A latex cryptococcal antigen agglutination test for diagnosis and monitoring of therapy for cryptococcosis. Aust Vet J 74 (5), 358-364 PubMed.
  • Malik R, Craig A J, Wigney D I et al (1996) Combination chemotherapy of canine and feline cryptococcosis using subcutaneously administered amphotericin B. Aust Vet J 73 (4), 124-128 PubMed.
  • Malik R, Dill-Macky E, Martin P et al (1995) Cryptococcosis in dogs - a retrospective study of 20 consecutive cases. J Med Vet Mycol 33 (5), 291-297 PubMed.
  • Cook J R, Evinger J V, Wagner L A (1991) Successful combination chemotherapy for canine cryptococcal meningoencephalitis. JAAHA 27 (1), 61-64 VetMedResource.
  • Mason G D, Labato M A, Bachrach A Jr. (1989) Ketoconazole therapy in a dog with systemic cryptococcosis. JAVMA 195 (7), 954-956 PubMed.
  • Hodgin E C, Corstvet R E, Blakewood B W (1987) Cryptococcosis in a pup. JAVMA 191 (6), 697-698 PubMed.
  • Noxon J O, Monroe W E, Chinn D R et al (1986) Ketoconazole treatment in canine and feline cryptococcosis. JAAHA 22 (2), 179-183 VetMedResource.

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