Actual problems of mycoses caused by dimorphic pathogens

Abstract

The literature review focuses on actual problems of the particularly dangerous mycoses – coccidioidomycosis, histoplasmosis, blastomycosis, paracoccidioidomycosis. The review presents modern data on the global spread of these fungal infections. Planetary climate changes widen the endemic areas of particularly dangerous mycoses by increase of the inhalational exposure of soil after dust storms, earthquakes and floodings. The prevaling view on the life cycle of agents of coccidioidomycosis (Coccidioides immitis, C.posadasii) is that these fungi dwell in soil (are saprobes) and so for them human and small-mammal fauna are only accidental hosts. The new alternative hypothesis implies that tissue form (spherule) of Coccidioides spp. lives in host granulomas of small mammals and transforms into spore producing hyphae when the animal host dies. It is demonstrated that Histoplasma capsulatum contains at least four different cryptic species, that differ genetically and express different virulence. Recently, discoveries of novel dimorphic systemic fungal pathogens have challenged the current taxonomy of family Ajellomycetacae. The new genus Emergomyces including five species is described. Another dimorphic pathogen is discovered and named Blastomyces percursus. These fungi cause disseminated mycoses globally, primarily in HIVinfected patients.