Histoplasma | |
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Tuberculate macroconidia of Histoplasma capsulatum | |
Scientific classification ![]() | |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Eurotiomycetes |
Order: | Onygenales |
Family: | Ajellomycetaceae |
Genus: | Histoplasma Darling (1906) |
Type species | |
Histoplasma capsulatum Darling (1906) | |
Species | |
Histoplasma capsulatum |
Histoplasma is a genus of fungi in the order Onygenales. [1] Species are known human pathogens producing yeast-like states under pathogenic conditions. They are the causative agents of histoplasmosis in humans and epizootic lymphangitis in horses. [2]
Histoplasma species have two forms: their environmental form is hyphal with microconidia and tuberculate macroconidia while their pathogenic form is a small intracellular yeast that exhibits narrow-necked budding [3] and no capsule. [4] [5] Infection occurs through inhalation of microconidia or small mycelial fragments. The dimorphic mold-yeast transforms and enters host macrophages and proliferates within them. Infections are most often seen in immunodeficient individuals. [6]
Species are mainly found in the Ohio and Mississippi River Valleys in the United States ( H.ohiense and H. mississippiense ) as well as Central ( H. capsulatum ) and South America ( H. suramericanum ), Africa ( H. duboisii ), Asia, and Australia. [7] [8]
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