Coccidioidomycosis

Key Features

Essentials of Diagnosis

• Acute infection: influenza-like illness, fever, backache, headache, fatigue and cough; erythema nodosum common

• Dissemination may result in meningitis, bony lesions, or skin and soft tissue abscesses

• Common opportunistic infection in patients with AIDS

• Chest radiograph findings vary from pneumonitis to cavitation

• Serologic tests useful; 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

Demographics

• Disseminated coccidioidomycosis occurs in about 0.1% of white and 1% of nonwhite patients. Filipinos and blacks and pregnant women of all races are especially susceptible

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

Clinical Findings

Symptoms and Signs

Primary coccidioidomycosis

• Incubation period is 10–30 days

• Symptoms, usually respiratory, occur in 40%

• Nasopharyngitis with 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

• Higher incidence of miliary infiltrates, lymphadenopathy, and meningitis in patients with AIDS, but skin lesions are uncommon

Differential Diagnosis

• Histoplasmosis, cryptococcosis, nocardiosis, blastomycosis

• Sarcoidosis

• Pneumoconiosis, eg, silicosis

• Tuberculosis

• Upper respiratory tract infection

• Atypical pneumonia

• Lymphoma (including lymphocytic interstitial pneumonitis)

Diagnosis

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 is as high as 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