coccidioidomycosis

  • background: dimorphic fungus, mold in environment, yeast in lung
  • location: SW, California, Arizona, New Mexico, Texas, Mexico, central/south America
  • epidemiology
    • endemic area: causes up to 1/3 pneumonia
    • lifetime risk of infection 3% in endemic areas
  • spread: inhaled and initially lung infection
  • pathogenesis: healthy person contains it with cell mediated immunity
  • sx:
    • initially lung infection
    • 40% cutaneous, 30% meningitis, msk
    • mimics other disease, TB, histo, sarcoid, cancer
  • dx
    • peripheral eosinophilia
    • serology
    • histopathology
  • rx
    • fluconazole
    • meningitis: fluconazole for life
    • amphotericin B alternative

Coccidioides is a dimorphic fungus that exists as a mold in the environment. There are two species: C. immitis refers to isolates from California, and C. posadasii refers to isolates from all other endemic areas, including Arizona, New Mexico, western Texas, northern Mexico, and parts of Central and South America. In endemic areas, the annual risk of infection is approximately 3% for most persons, although the risk of infection (and dissemination) is greater in those who are pregnant, younger than 5 years or older than 50 years, or of African, Filipino (and possibly other Asian), and Native American ancestry.

A 27-year-old man is evaluated in the hospital for a 1-month history of fever, drenching night sweats, malaise, fatigue, chest pain, and a nonproductive cough. He recently completed a 7-day course of levofloxacin with no improvement in symptoms. The patient is in the military, works as a car mechanic on base, and is stationed in Bakersfield, California.

On physical examination, temperature is 37.8 °C (100.0 °F), blood pressure is 128/76 mm Hg, pulse rate is 99/min, respiration rate is 24/min, and oxygen saturation is 92% with the patient breathing room air. The remainder of the physical examination is unremarkable.

Laboratory studies:

  • Hemoglobin 12.4 g/dL
  • Leukocyte count: 11,900/µL, with 30% eosinophils, 60% neutrophils, and 10% lymphocytes
  • Interferon-γ release assay: Negative

A chest radiograph shows a right lower lobe infiltrate and ipsilateral hilar lymphadenopathy.

Primary pulmonary tuberculosis may present with midto lower-zone unilateral infiltrates, unilateral hilar lymphadenopathy, and pleural effusions. Early in the course of the disease, laboratory findings are often normal; eosinophilia is not present. Finally, pulmonary tuberculosis is excluded by the negative interferon-γ release assay.