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Histoplasma capsulatum
Published in Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward, Case Studies in Infectious Disease, 2010
Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward
Histoplasma capsulatum causes a systemic endemic mycosis called histoplasmosis (sometimes called Darling’s disease). The genus Histoplasma (Ajellomyces) from the family Onygenales contains one species, Histoplasma capsulatum. There are three varieties: H. capsulatum var. capsulatum, which causes the common histoplasmosis, H. capsulatum var. duboisii, a cause of African histoplasmosis (histoplasmosis duboisii), and H. capsulatum var. farciminosum, which causes lymphangitis in horses. Some Histoplasma isolates may resemble species of Sepedonium and Chrysosporium.
Granulomas and Granulomatous Inflammation
Published in Philip T. Cagle, Timothy C. Allen, Mary Beth Beasley, Diagnostic Pulmonary Pathology, 2008
The African variant is H. duboisii, which is larger than H. capsulatum. Lung lesions in African histoplasmosis are less frequent than with the North American form. Epithelioid cell granulomas are seen in both; however, necrotizing granulomas are more frequent in H. capsulatum–induced lesions (Fig. 11B). Leishmania species might be mistaken for Histoplasma; however, these former organisms can be differentiated by their kinetoplasts (Giemsa) and their PAS-negative cell wall. In addition, Leishmania infection in the lungs does not induce a granulomatous reaction.
The Diagnosis of Endemic Mycoses
Published in Johan A. Maertens, Kieren A. Marr, Diagnosis of Fungal Infections, 2007
John R. Graybill, Gregory M. Anstead, Flavio Queiroz-Telles
The major endemic mycoses are defined by their heightened prevalence in specific geographic regions. In the Americas, Histoplasma capsulatum is concentrated in the Midwestern United States, most densely within the Ohio and Mississippi River basins, and south through Mexico, Central America, into South America, particularly Colombia, Venezuela, Brazil, and Argentina (1). African histoplasmosis, due to H. capsulatum var. duboisii is a much less common disease and is found in Central and Western Africa (2). There have also been cases of H. capsulatum var. capsulatum reported in South Africa.
Zoonotic fungal diseases and animal ownership in Nigeria
Published in Alexandria Journal of Medicine, 2018
Adebowale I. Adebiyi, Daniel O. Oluwayelu
Histoplasmosis is an infection caused by Histoplasma capsulatum, a dimorphic fungus with two known varieties: H. capsulatum var. capsulatum and H. capsulatum var. duboisii. The two varieties have been identified in Africa. African histoplasmosis caused by H. capsulatum var. duboisii is a deep mycosis endemic in the African continent, essentially between the Tropics of Cancer and Capricon47,48 as well as in the island of Madagascar.49 It has been detected in about 20 countries in tropical Africa located between 20° North and 20° South of the Equator and extending from Senegal in the West to Tanzania in the East.47,48,50,51 This region is characterized by high average rainfall, high humidity and little variation in diurnal temperature.48
Disseminated histoplasmosis: case report and review of the literature
Published in Acta Clinica Belgica, 2018
Séverine Evrard, Philippe Caprasse, Pierre Gavage, Myriam Vasbien, Jean Radermacher, Marie-Pierre Hayette, Rosalie Sacheli, Marjan Van Esbroeck, Lieselotte Cnops, Eric Firre, Laurent Médart, Filip Moerman, Jean-Marc Minon
Another variety of Histoplasma capsulatum, Histoplasma capsulatum var. duboisii, causes African histoplasmosis. The two varieties are genetically close but clinical and morphological features allow differentiation of these two diseases. Firstly, although lymph node, spleen, hepatic, pulmonary, or gastrointestinal lesions have also been described, African histoplasmosis usually involves skin, subcutaneous tissue and bones. Furthermore, yeasts in macrophages are much larger than those observed in the variety capsulatum: they are oval or lemon-shaped, thick walled and measure 8–15 μm long (vs. 5 μm at the maximum for capsulatum variety) [31]. Moreover, H. capsulatum var. duboisii infection is rarely found In HIV-positive patients [32]. Geographic distribution also plays a role for differentiation, as duboisii variety is only encountered on the African continent.
Endemic mycoses: epidemiology and diagnostic strategies
Published in Expert Review of Anti-infective Therapy, 2020
Andrés Tirado-Sánchez, Gloria M. González, Alexandro Bonifaz
In some countries such as the Philippines and Indonesia, it is likely to be underdiagnosed, reflecting fewer reported cases [28]. In other countries such as India, Bangladesh, Nepal, Pakistan, and Sri Lanka, reported cases have rebounded [28,30]. Africa is an endemic zone for African histoplasmosis caused by H. capsulatum var. duboisii, mainly in areas of central and western Africa (Nigeria, Niger, Senegal, the Democratic Republic of the Congo, Zaire, and Uganda) and the island of Madagascar. Most cases of H. capsulatum var. capsulatum have been reported in Tanzania, Zimbabwe, and South Africa [31].