Canis ISSN: 2398-2942

Coccidioides immitis

Contributor(s): Rosanna Marsella

Introduction

Classification

Taxonomy

  • Dimorphic fungus.

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Clinical Effects

Epidemiology

Habitat

  • C. immitis inhabits the soil in the Lower Sonoran Life Zone.
  • High prevalence is associated with an annual rainfall of 125-500 mm and mean summer and winter temperatures of more than 27°C and more than 7°C respectively.

Lifecycle

  • Arthrospores grow into spherules in tissue.
  • The walls disintegrate and endospores are liberated and repeat the cycle in the host or on a non-living substrate; develop into mycelial growth.

Transmission

  • Inhalation of dust.
  • Primary cutaneous infection (rare).

Pathological effects

  • Cell-mediated immunity develops early and can persist indefinitely and indicates resistance; disappears in disseminated disease.
  • IgM appears initially and then disappears.
  • IgG titers rise in disseminated disease and remain high until after recovery.
  • Infection occurs by inhalation of spores.
  • Primarily a disease of the lungs and secondarily a disease of bones and other organs.
  • Inflammatory response occurs but phagocytes unable to kill the arthrospores. They are carried to the lymph nodes where other inflammatory foci occur. Usually arrested at this stage if cell-mediated immunity is not compromised, otherwise dissemination occurs.
  • Dogs: lassitude, anorexia, cough, fever, lameness, discharging sinuses, weight loss, peripheral lymphadenopathy. Some cases may be mild or sub-clinical.

Other Host Effects

  • Disease occurs in dogs and humans; subclinical in other animals.

Control

Control via chemotherapies

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Burtch M (1998) Granulomatous meningitis caused by Coccidioides immitis in a dog. JAVMA 212(6), 827-829.
  • Johnson S M, Zimmermann C R & Pappagianis D (1996) Use of a recombinant Coccidioides immitis complement fixation antigen-chitinase in conventional serological assays. J Clin Microbiol 34(12), 3160-3164.
  • Chapman S W & Daniel C R (1994) Cutaneous manifestations of fungal infections. Infect Dis Clin North Am 8(4), 879-910.
  • Sekkon A S et al (1991) Review of human and animal cases of coccidioidomycosis diagnosed in Canada. Mycopathologica 113, 1.

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