Blastomyces dermatitidis

Blastomyces dermatitidis is a thermally dimorphic fungus that is found in the environment as a mold and in tissue as a yeast. It is the causative agent of the disease blastomycosis, which primarily affects the lungs but can also involve other organs and systems.

Epidemiology

Blastomyces dermatitidis is endemic in certain areas of the United States, particularly in the Mississippi and Ohio River valleys, the Great Lakes region, and the southeastern states. It is also found in parts of Canada, Africa, and the Middle East. The fungus is found in soil and decaying organic matter, particularly in areas near water.

Pathogenesis

Infection with Blastomyces dermatitidis occurs through inhalation of airborne conidia. Once in the lungs, the conidia convert to the yeast form and can cause a localized pulmonary infection. The yeast can also disseminate to other parts of the body, causing extrapulmonary disease.

Clinical Manifestations

The clinical manifestations of blastomycosis can range from asymptomatic infection to severe disseminated disease. Pulmonary symptoms can include cough, chest pain, and shortness of breath. Extrapulmonary manifestations can include skin lesions, bone and joint pain, and genitourinary symptoms.

Diagnosis

Diagnosis of blastomycosis is typically made through identification of the yeast in clinical specimens, such as sputum or tissue biopsies. Serologic tests and molecular methods can also be used.

Treatment

Treatment of blastomycosis typically involves antifungal medications, such as itraconazole or amphotericin B. The duration of treatment depends on the severity and location of the disease.

Prevention

Prevention of blastomycosis primarily involves avoiding activities that disturb soil in endemic areas. There is currently no vaccine available for blastomycosis.

See Also

• Blastomycosis
• Fungal diseases
• Pulmonary diseases

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