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 VetMed Resource and PubMed.
  • Malik R, Speed B R, Kaldor J, Cairns B, Pegorer M, Wigney D I & Love D N (1999) Serum antibody response to Cryptococcus neoformans in cats, dogs and koalas with and without active infection. Med Mycol 37(1), 43051.
  • Malik R, Hunt G B, Bellenger C R, Allan G S, Martin P, Canfield P J & Love D N (1999) Intra-abdominal cryptococcosis in two dogs. JSAP 40(8), 387-391.
  • Tiches D, Vite C H, Dayrell-Hart B, Steinbery S A, Gross S & Lexa F (1998) A case of canine central nervous system cryptococcosis - management with fluconazole. JAAHA 34(2), 145-151.
  • Malik R, McPetrie R, Wigney D I, Craig A J & Love D N (1996) A latex cryptococcal antigen agglutination test for diagnosis and monitoring of therapy for cryptococcosis. Aust Vet J 74(5), 358-365.
  • Malik R, Craig A J, Wigney D I, Martin P & Love D N (1996) Combination chemotherapy of canine and feline cryptococcosis using subcutaneously administered amphotericin B. Aust Vet J 73(4), 124-128.
  • Malik R, Dill-Macky E, Martin P, Wigney D I, Muir D B & Love D N (1995) Cryptococcosis in dogs - a retrospective study of 20 consecutive cases. J Med Vet Mycol 33(5), 291-297.
  • Cook J R et al (1991) Successful chemotherapy for canine cryptococcal meningoencephalitis. JAAHA 27, 61.
  • Mason G D et al (1989) Ketaconazole therapy in a dog with systemic cryptococcosis. JAVMA 195, 954.
  • Hodgin E C et al (1987) Cryptococcosis in a pup. JAVMA 191, 697.
  • Noxon J O et al (1986) Ketoconazole treatment in canine and feline cryptococcosis. JAAHA 22, 179.

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