Blastomycosis

KEY FEATURES

• Most often in men infected during outdoor activities

• Geographically limited to south central and midwestern United States and Canada

CLINICAL FINDINGS

• Pulmonary infection most common; may be asymptomatic

• Cough, fever, dyspnea, chest pain; may resolve or progress, with purulent sputum, pleurisy, fever, chills, weight loss, prostration

• When disseminated, lesions mostly affect skin, bones, urogenital system

• Raised, verrucous cutaneous lesions commonly present in disseminated disease

• Bone lesions often in ribs and vertebrae

• Epididymitis, prostatitis, and other involvement of the male urogenital system

• Central nervous system (CNS) involvement uncommon

• In persons with HIV, disease may progress rapidly; dissemination common

DIAGNOSIS

• Leukocytosis and anemia

• Chest radiograph or CT scan: lobar consolidations or masses

• Clinical specimen: organism is a thick-walled cell 5–20 mcm in diameter; may have single broad-based bud; blastomyces grows readily on culture

• Serum enzyme immunoassay based on the surface protein BAD-1

  • Appears to have better sensitivity and specificity than urinary antigen test

• A urinary antigen test is available

  • Has considerable cross reactivity with other dimorphic fungi

  • May be useful in monitoring disease resolution or progression

  • Quantitative antigen enzyme immunoassay may be helpful in diagnosing CNS disease

TREATMENT

• Itraconazole, 200–400 mg orally once daily for at least 6–12 months, for nonmeningeal disease; response rate of > 80%

• Liposomal amphotericin B, 3–5 mg/kg/d intravenously, should be given initially in severe disease or CNS involvement, or for treatment failure

• Monitor patients several years for relapse