Histoplasma, Blastomyces, Coccidioides, Paracoccidioides and Other Dimorphic Fungi Causing Systemic Mycoses

The dimorphic fungi causing systemic disease belong to the class Eurotiomycetes, order Onygenales. This chapter covers the dimorphic members of the families Onygenaceae and Ajellomycetaceae. Ajellomycetaceae contains the species Ajellomyces dermatitidis, A. capsulatum, A. duboisii, and A. crescens, the anamorphs of which have been placed in the genera Blastomyces and Histoplasma. DNA sequence data place Paracoccidioides in the family Ajellomycetaceae as well. However, it is important to appreciate that tissue-form cells of Histoplasma and Blastomyces can appear similar to each other as well as to yeast cells of various Candida species, Cryptococcus neoformans, Cryptococcus gattii, and Talaromyces marneffei and to endospores of Coccidioides species.