Symptoms of primary coccidioidomycosis occur in about 40% of infections. Symptom onset (after an incubation period of 10–30 days) is usually that of a respiratory tract illness with fever and occasionally chills. Coccidioidomycosis is a common, frequently unrecognized, etiology of community-acquired pneumonia in endemic areas.
Arthralgia accompanied by periarticular swelling, often of the knees and ankles, is common. Erythema nodosum may appear 2–20 days after onset of symptoms. Persistent pulmonary lesions, varying from cavities and abscesses to parenchymal nodular densities or bronchiectasis, occur in about 5% of diagnosed cases.
Disseminated disease occurs in about 0.1% of white and 1% of nonwhite patients. Filipinos and blacks are especially susceptible, as are pregnant women of all races. Any organ may be involved. Pulmonary findings usually become more pronounced, with mediastinal lymph node enlargement, cough, and increased sputum production. Lung abscesses may rupture into the pleural space, producing an empyema. Complicated skin and bone infections may develop. Fungemia may occur and is characterized clinically by a diffuse miliary pattern on chest radiograph and by early death. The course may be particularly rapid in immunosuppressed patients. Clinicians caring for immunosuppressed patients in endemic areas need to consider that patients may be latently infected.
Meningitis occurs in 30–50% of cases of dissemination and may result in chronic basilar meningitis. Subcutaneous abscesses and verrucous skin lesions are especially common in fulminating cases. Lymphadenitis may occur and may progress to suppuration. Patients with AIDS with disseminated disease have a higher incidence of miliary infiltrates, lymphadenopathy, and meningitis, but skin lesions are uncommon.
In primary coccidioidomycosis, there may be moderate leukocytosis and eosinophilia. Serologic testing is useful for both diagnosis and prognosis. The immunodiffusion tube precipitin test and enzyme-linked immunosorbent assay (ELISA) detect IgM antibodies and are both useful for diagnosis early in the disease process. A persistently rising IgG complement fixation titer (1:16 or more) is suggestive of disseminated disease; in addition, immunodiffusion complement fixation titers can be used to assess the adequacy of therapy. Serum complement fixation titers may be low when there is meningitis but no other disseminated disease. In patients with HIV-related coccidioidomycosis, the false-negative rate may be as high as 30%. Blood cultures are rarely positive.
Patients in whom coccidioidomycosis is diagnosed should undergo evaluation for meningeal involvement when CNS symptoms or neurologic signs are present. Spinal fluid findings include increased cell count with lymphocytosis and reduced glucose. Spinal fluid culture is positive in approximately 30% of meningitis cases. Demonstrable complement-fixing antibodies in spinal fluid are diagnostic of coccidioidal meningitis. These are found in over 90% of cases; Coccidioides antigen or (1,3)-beta-D-glucan testing may augment (not replace) CSF antibody testing.
Radiographic findings vary, but patchy, nodular, and lobar upper lobe pulmonary infiltrates are most common. Hilar lymphadenopathy may be visible and is seen in localized disease; mediastinal lymphadenopathy suggests dissemination. There may be pleural effusions and lytic lesions in bone with accompanying complicated soft tissue collections.