Histoplasma
Tuberculate macroconidia of Histoplasma capsulatum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Onygenales
Family: Ajellomycetaceae
Genus: Histoplasma
Darling (1906)
Type species
Histoplasma capsulatum
Darling (1906)
Species

Histoplasma capsulatum
Histoplasma duboisii
Histoplasma mississippiense (nom. inval.)
Histoplasma ohiense (nom. inval.)
Histoplasma suramericanum (nom. inval.)


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]

Forms / Stages

Histoplasma species have two forms: their environmental form is hyphal with microconidia and tuberculate macroconidia while their pathogenic form is a small intracellular yeast with a narrow neck and no bud with no capsule.[3] 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.[4]

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.[5][6]

References

  1. ^ Jiang Y, Dukik K, Munoz JF, Sigler L, Schwartz IS, Govender NP, Kenyon C, Feng P, van den Ende BG, Stielow JB, Stchigel AM, Lu H, de Hoog S (2018). "Phylogeny, ecology and taxonomy of systemic pathogens and their relatives in Ajellomycetaceae (Onygenales): Blastomyces, Emergomyces, Emmonsia, Emmonsiellopsis". Fungal Diversity. 90: 245–291. doi:10.1007/s13225-018-0403-y.
  2. ^ OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2004 Chapter 2.5.13, "Archived copy". Archived from the original on 2007-08-04. Retrieved 2007-06-14.((cite web)): CS1 maint: archived copy as title (link)
  3. ^ Hutton, JP (April 1985). "Hyphal forms of Histoplasma capsulatum. A common manifestation of intravascular infections". Archives of Pathology and Laboratory Medicine. 109 (4): 330–332. PMID 3885898 – via Pubmed.
  4. ^ Lopez, CE (Oct 2006). "Dimorphism and pathogenesis of Histoplasma capsulatum". Revista Argentina de Microbiologia. 38 (4): 235–242. PMID 17370580 – via Pubmed.
  5. ^ "Histoplasmosis". Centers for Disease Control and Prevention. 28 October 2020. Retrieved 27 January 2021.
  6. ^ Sepúlveda VE, Márquez R, Turissini DA, Goldman WE, Matute DR (2017). "Genome sequences reveal cryptic speciation in the human pathogen Histoplasma capsulatum". mBio. 8 (6). doi:10.1128/mbio.01339-17.



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