Histoplasmosis

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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Histoplasmosis is a disease, usually affecting the lungs, caused by the Histoplasma capsulatum fungus. Although many people that are or have been infected with H. capsulatum do not appear ill, some people in the acute phase of the disease have a dry cough, fever, and chest pains and do feel ill. There are several types of histoplasmosis (acute, chronic, and disseminated, all with subtypes).

H. capsulatum was first described by Samuel Darling in 1906 within human tissue cells (histiocytes). In 1932, Katharine Dodd and Edna Tompkins made the first diagnosis of histoplasmosis in an infant. Since the 1930s, H. capsulatum has been found worldwide, but the majority of cases are found in river valleys in temperate regions of the world and in equatorial Africa (in Africa, H. capsulatum has a variant thick-walled yeast form termed H. duboisii). Often an outbreak occurs in a group of people after a visit to a certain area like a cave that contains bat droppings. In the U.S., histoplasmosis is endemic in the Ohio, Missouri, and Mississippi river valleys.

Histoplasmosis is the most common endemic fungal infection diagnosed in the U.S. with about 250,000 new cases per year. H. capsulatum can occur in high concentrations in some sources (for example, bird and bat feces). Histoplasmosis has also been named Ohio River Valley fever and bird-fancier's disease. Histoplasmosis can affect other mammals like dogs and cats, but these animals do not transfer the disease to humans or to other animals. Dogs, cats, and other mammals develop symptoms mainly due to lung infections with H. capsulatum that mimic human histoplasmosis.