Histoplasma

Histoplasma
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 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 and 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 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]}

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 . hdl: 10067/1520590151162165141 .
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.
3. Mittal, Jamie; Ponce, Maria G.; Gendlina, Inessa; Nosanchuk, Joshua D. (2019). "Histoplasma Capsulatum: Mechanisms for Pathogenesis". In Rodrigues, Marcio L. (ed.). Fungal Physiology and Immunopathogenesis. Current Topics in Microbiology and Immunology volume 422. Vol. 422. Springer Nature Switzerland AG. pp. 157–191. doi:10.1007/82_2018_114. ISBN   978-3-030-30236-8. PMC   7212190 . PMID   30043340.
4. Mahajan, Monika (2021). "Etymologia: Histoplasma capsulatum". Emerging Infectious Diseases. 27 (3): 969. doi: 10.3201/eid2703.et2703 . PMC   7920646 .
5. 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.
6. Lopez, CE (Oct 2006). "Dimorphism and pathogenesis of Histoplasma capsulatum". Revista Argentina de Microbiologia. 38 (4): 235–242. PMID   17370580.
7. "Histoplasmosis". Centers for Disease Control and Prevention. 28 October 2020. Retrieved 27 January 2021.
8. 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): e01339-17. doi: 10.1128/mbio.01339-17 . PMC   5717386 . PMID   29208741.