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For further information, see CMDT Part 36-04: Coccidioidomycosis

Key Features

Essentials of Diagnosis

  • Acute infection is an influenza-like illness with malaise, fever, backache, headache, and cough; erythema nodosum common

  • Dissemination may result in meningitis, arthralgias, bone lesions, or skin and soft tissue abscesses; common opportunistic infection in AIDS

  • Chest radiograph varies from pneumonitis to cavitation

  • Serologic tests useful for diagnosis

  • Large spherules containing endospores demonstrable in sputum or tissues

General Considerations

  • Consider this diagnosis in any obscure illness in a patient who has been in an endemic area

  • Infection results from inhalation of Coccidioides immitis or Coccidioides posadasii; both are molds that grow in soil of southwestern United States, Mexico, and Central and South America

  • Dissemination occurs in < 1% of immunocompetent persons, but mortality of disseminated disease is high


  • Disseminated coccidioidomycosis occurs in about 0.1% of White and 1% of non-White patients; those who are Filipino or Black, and pregnant women of all races, are especially susceptible

  • In endemic areas, coccidioidomycosis is a common opportunistic infection with risk for dissemination in HIV-infected individuals

Clinical Findings

Symptoms and Signs

Primary coccidioidomycosis

  • Incubation period is 10–30 days

  • Symptoms, usually respiratory, occur in 40%

  • Fever and chills

  • A common, though frequently unrecognized, cause of community-acquired pneumonia in endemic areas

  • Arthralgias with periarticular swelling of knees and ankles

  • Erythema nodosum can develop 2–20 days after symptom onset

  • Persistent pulmonary lesions develop in 5%

Disseminated coccidioidomycosis

  • Can involve any organ

  • Productive cough

  • Enlarged mediastinal lymph nodes

  • Lung abscesses, empyema

  • Complicated skin and bone infections

  • Untreated in immunocompromised patients, fungemia with diffuse miliary infiltrates on chest radiograph and early death

  • Meningitis in 30–50% and may result in chronic basilar meningitis

  • Subcutaneous abscesses and verrucous skin lesions

  • Lymphadenitis may progress to suppuration

  • Disseminated in HIV-infected patients more often shows miliary infiltrates, lymphadenopathy, and meningitis, but skin lesions are uncommon


Laboratory Tests

  • In primary coccidioidomycosis, moderate leukocytosis and eosinophilia

  • IgM antibodies are positive in early disease

  • In disseminated coccidioidomycosis, rising serum complement fixation titer (≥ 1:16); titers can be used to assess treatment adequacy

    • Complement fixation titer may be low in meningitis without other disseminated disease

    • In HIV-infected patients, complement fixation false-negative rate may reach 30%

  • Coccidioides antigen testing may augment CSF antibody testing

  • In coccidioidal meningitis, cerebrospinal fluid (CSF) complement fixation antibodies are positive in > 90%. CSF shows increased cell count, lymphocytosis, and reduced glucose, and positive cultures are found in 30%

  • Blood cultures are rarely positive

Imaging Studies

  • Chest radiographic findings vary

    • Nodular and lobar upper lobe pulmonary infiltrates are most common

    • Hilar ...

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