Acute pulmonary histoplasmosis is a respiratory infection that is caused by inhaling the spores of the fungus Histoplasma capsulatum.
Histoplasma capsulatum is the name of the fungus that causes histoplasmosis. It is found in the central and eastern United States, eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia. It is commonly found in the soil in river valleys. It gets into the soil mostly from bird and bat droppings.
You can get sick when you breathe in spores that the fungus produces. Every year, thousands of people with a normal immune system worldwide are infected, but most do not become seriously sick. Most have no symptoms or have only a mild flu-like illness and recover without any treatment.
Acute pulmonary histoplasmosis may happen as an epidemic, with many people in one region becoming sick at the same time. People with weakened immune systems (see Symptoms section below) are more likely to:
Risk factors include traveling to or living in the central or eastern United States near the Ohio and Mississippi river valleys, and being exposed to the droppings of birds and bats. This threat is greatest after an old building is torn down and spores get into the air, or when exploring caves.
Most people with acute pulmonary histoplasmosis have no symptoms or only mild symptoms. The most common symptoms are:
Acute pulmonary histoplasmosis can be a serious illness in the very young, older people, and people with a weakened immune system, including those who:
Symptoms in these people may include:
To diagnose histoplasmosis, you must have the fungus or signs of the fungus in your body. Or your immune system must show that it is reacting to the fungus.
Most cases of histoplasmosis clear up without specific treatment. People are advised to rest and take medicine to control fever.
Your health care provider may prescribe medicine if you are sick for more than 4 weeks, have a weakened immune system, or are having breathing problems.
When histoplasmosis lung infection is severe or gets worse, the illness may last up to many months. Even then, it is rarely fatal.
The illness can get worse over time and become a long-term (chronic) lung infection (which doesn't go away).
Histoplasmosis can spread to other organs through the bloodstream (dissemination). This is often seen in infants, young children, and people with a suppressed immune system.
Call your provider if:
Avoid contact with bird or bat droppings if you are in an area where the spore is common, especially if you have a weakened immune system.
Deepe GS. Histoplasma capsulatum (histoplasmosis). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 263.
Kauffman CA, Galgiani JN, Thompson GR. Endemic mycoses. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 316.BACK TO TOP
Review Date: 3/4/2020
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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