Peter G. Pappas, M.D.


Semin Respir Crit Care Med. 2004;25(2) 

In This Article

Abstract and Introduction

Blastomycosis is an endemic fungal infection predominantly seen in the south central and mid-western United States and portions of Canada. The disorder is caused by Blastomyces dermatitidis, a dimorphic organism usually acquired through inhalation of aerosolized conidia. Most acutely infected patients are asymptomatic or develop a self-limited respiratory illness. Chronic pneumonia is the dominant clinical manifestation of blastomycosis, although extrapulmonary disease is common, usually involving skin and subcutaneous tissue, bones and joints, the prostate gland, and the central nervous system (CNS). Chronic blastomycosis should always be treated with systemic antifungal therapy, and oral itraconazole is the drug of choice for mild to moderate forms of the disease. Severe manifestations, including adult respiratory distress syndrome, CNS involvement, and disease in severely immunocompromised hosts require primary therapy with an amphotericin B formulation. There are no routine measures to prevent blastomycosis, although there is promising experimental data involving the use of a live, attenuated vaccine.

Blastomycosis is an endemic fungal infection of North America that is caused by the thermally dimorphic fungus, Blastomyces dermatitidis.[1] Most disease occurs among people living in the south central, mid-western, and Great Lakes region of the United States, and portions of Canada.[2,3,4,5] Recent reports have demonstrated rare cases occurring in traditionally non-endemic areas such as Colorado,[6] suggesting a somewhat more diverse geographic area of endemicity than was previously recognized.

Gilchrist first described blastomycosis in 1894, mistakenly attributing the disease to a protozoan.[7] Soon thereafter, the causative agent was determined to be a fungus, and the organism was termed Blastomyces dermatitidis.[8] Over the ensuing decades, the disease became known by several names, including Gilchrist's disease and Chicago disease. The term North American blastomycosis, a commonly uses synonym, evolved to distinguish this disorder from the clinically similar South American blastomycosis, a disease caused by Paracoccidioides brasiliensis. It was not until 1951, following the detailed pathologic description of blastomycosis by Schwarz and Baum,[9] that it was discovered that most cases of the disorder were acquired via the respiratory, not cutaneous, route of inoculation.


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