Infections Due to the Dimorphic Fungi

Abstract

The thermally dimorphic fungi grow as molds in the natural environment or in the laboratory at 25–30°C, and as yeasts or spherules in tissue or when incubated on enriched media at 37 °C. They include the agents of the endemic systemic mycoses prevalent in the Western Hemisphere, i.e., Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis, and Paracoccidioides brasiliensis. Also discussed here are Sporothrix schenckii, which occurs worldwide and usually causes cutaneous rather than systemic disease, and Penicillium marneffei, a recently recognized cause of systemic mycosis in Southeast Asia. In recent years, these fungi have become an increasing problem due to rising populations in the endemic areas, more travel, and an increasing number of immunocompromised patients (especially those with AIDS). Because of space limitations we have tried to emphasize more recent developments in the ecology, epidemiology, and clinical aspects of these mycoses. Pathogenesis and host defense are reviewed in other chapters (Chaps. 1, 3, 4, this Vol.).