ISSN 2398-2969      

Fungal lung disease: coccidioidomycosis

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Introduction

  • Systemic mycotic infection.
  • Etiological agent: soil-borne, dimorphic fungus, Coccidioides immitis Coccidioides immitis.
  • Signs of infection: cough, respiratory distress, lameness, peripheral lymphadenopathy, ocular signs, cutaneous draining tracts.
  • Route of infection: inhalation.
  • Diagnosis: characteristic pulmonary, skin, ocular, or orthopedic lesions.
  • Identification: of organism in cytological or histopathological samples.
  • Treatment: Itraconazole, ketaconazole, and other antifungal agents.
  • Prognosis: Good to guarded.

Pathogenesis

Etiology

Predisposing factors

General
  • Young male dogs.
  • Exposure to a common source outside in an endemic area.
  • Outbreaks of the disease occur after rainy periods, dust storms and earthquakes.
  • Increased prevalence of the disease occurs in late summer and early fall.

Pathophysiology

  • The organism primarily gains entry into the body via inhalation.
  • The inhaled arthroconidia convert in the lung to a yeast phase, characterized by spherule formation that undergoes division, producing endospores.
  • Typically, the cell-mediated immune system clears the infection rapidly.
  • In some cases, endospores are released and disseminate to the hilar lymph nodes and distant tissues eg bones, skin, eyes, heart, testicles, central nervous system, liver, spleen and/or kidneys.
  • Isolated cutaneous disease may occur from contamination of wounds with the organism.
  • With a normal immune system and without an overwhelming infective burden the infection is rapidly cleared via cell-mediated immune system mechanisms.
  • In some cases the organism disseminates throughout the body.

Timecourse

  • Incubation time is typically 1-3 weeks.
  • Initial pulmonary infection may go undetected.
  • Subclinical forms of the disease may persist, with clinically obvious disseminated disease occurring months to years later.

Epidemiology

  • Organism present throughout the southwestern United States, Mexico, Central America and South America.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Johnson L R, Herrgesell E J, Davidson A P, Pappagianis D (2003) Clinical, clinicopathologic and radiographic findings in dogs with coccidioidomycosis: 24 cases (1995-2000). J Am Vet Med Assoc 222 (4), 461-466 PubMed.
  • Bartsch R, Greene R T (1998) Lufenuron in the treatment of coccidioidomycosis. Capsule Report 16 (3), 1998.
  • Burtch M (1998) Granulomatous meningitis caused by Coccidioides immitis in a dog. J Am Vet Med Assoc 212 (6), 827-829 PubMed.
  • Plotnick A N, Oshoven E W, Rosychuk R A (1997) Primary cutaneous coccidioidomycosis and subsequent drug eruption to itraconazole in a dog. J Am Anim Hosp Assoc 33 (2), 139-143 PubMed.
  • 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 PubMed.
  • Davidson A P (1995) Canine coccidioidomysosis update. Proc Am Coll Vet Intern Med 13, 808.
  • Sekhon A S, Isaac-Renton J, Dixon J M, Stein L & Sims H V (1991) Review of human and animal cases of coccidioidomycosis diagnosed in CanadaMycopathologia 113 (1), 1-10 PubMed.
  • Hawkins E C & DeNicola D B (1990) Cytologic analysis of tracheal wash specimens and bronchoalveolar lavage fluid in the diagnosis of mycotic infections in dogs. J Am Vet Med Assoc 197 (1), 79-83 PubMed.
  • Angell J A, Merideth R E, Shively J N et al (1987) Ocular lesions associated with coccidioidomycosis in dogs: 35 cases (1980-1985)J Am Vet Med Assoc 190 (10), 1319-1322 PubMed.

Other sources of information

  • Greene R T (1998) Coccidiodomycosis In: Infectious diseases of the dog and cat. Ed C E Greene. Philadelphia: W B Saunders. pp 391-398.
  • Taboada J (2002) Systemic mycoses. In: Morgan R V, Bright R N, Swartout MS (eds): Handbook of Small Animal Practice. 4th Ed. W B Saunders, Philadelphia, pp1075-1089.

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