Blastomycosis

Key Features

• Most often in men infected during outdoor activities

• Geographically limited to south central and midwestern US and Canada

Clinical Findings

• Chronic 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

• With disseminated, lesions most frequently occur in 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

• CNS involvement uncommon

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

Diagnosis

• Leukocytosis and anemia

• Chest radiograph or CT scan: lobar consolidations or masses

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

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

  • Has better sensitivity and specificity than urinary antigen test

  • Not yet commercially available

• A urinary antigen test is available

  • Has considerable cross reactivity with other dimorphic fungi

  • May be useful in monitoring disease resolution or progression

Treatment

• Itraconazole, 200–400 mg orally once daily for at least 6–12 mo, for non–life-threatening, non-CNS disease; response rate of > 80%

• Liposomal amphotericin B, 3–5 mg/kg/day intravenously, is given initially for severe disease, treatment failures, or CNS involvement

• Monitor patients several years for relapse