Article Sections

Introduction

The systemic mycoses include 3 fungal infections:  histoplasmosis (Histoplasma capsulatum), blastomycosis (Blastomyces dermatitidis), and coccidioidomycosis (Coccidioides immitis) ( Table 1).  This article specifically addresses histoplasmosis.  Although there are differences in their geographic distribution and pattern of organ involvement, the systemic mycoses share fundamental similarities:

  • Endemic:  ubiquitous in the soil (ie, community-acquired) and easily aerosolized.
  • Dimorphic:  exist as a mold (ie, hyphal form) in the environment, but as an intracellular (mainly in macrophages) budding yeast or spherules in human hosts.
  • Pulmonary:  manifest primarily as a pneumonia, with potential extrapulmonary involvement as well (eg, lymph nodes [histoplasmosis], skin and bone [blastomycosis], and meninges [coccidioidomycosis]).
  • Nonopportunistic:  able to cause significant local infection (eg, pneumonia) in immunocompetent hosts (with sufficient inoculum).  They also have a propensity to cause disseminated disease in immunocompromised patients.

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Tables

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