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Coccidioides

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Summary

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Key Points

  • Coccidioides spp.
    • Includes C. immitis, C. posadasii
    • Characteristics
      • Dimorphic fungi
        • Exists as a mold in the soil, outside body (20ºC) (FA/MB)
        • Exists as a large spherule inside body tissues (37ºC) (FA/MB)
          • Unlike other mycoses, which exist as yeasts in tissues
          • exists as spherules in human tissues. Spherules are covered by a capsule and contain endospores.
    • Transmission
      • Endemic to southwestern US
        • South-central Arizona, the San Joaquin Valley and adjacent areas of California, regions of southern Nevada and Utah, southwestern New Mexico, and western Texas
        • Associated with dust exposure in endemic areas (e.g. archeological digs, earthquakes)
      • Inhalation of spores (MB)
      • Cannot be transmitted from person to person (unlike TB)
    • Presentation
      • Causes Coccidioidomycosis
        • Pneumonia
          • Fever, dry cough, with pulmonary infiltrates, hilar adenopathy
          • may resemble acute TB
        • Arthralgias (desert rheumatism)
          • symmetric arthralgias, particularly of the ankles, knees, and wrists
        • Skin manifestations
          • Erythema nodosum (desert bumps)
            • painful, erythematous nodules on the lower extremities
          • Erythema multiforme
            • Hypersensitivity reaction with a typical target lesion
            • Seen in a necklace distribution
    • Diagnosis
      • Histopathology
        • Spherule filled with endospores of Coccidioides
          • Much larger than RBC
        • Can form granulomas (like TB)
      • Detection of anti-coccidioidal antibodies in serum is used
    • Treatment
      • In healthy patients with mild infections, antifungal agents is not indicated
      • Fluconazole or itraconazole for local severe infection
      • Amphotericin B for systemic severe infection