Acute pulmonary histoplasmosis is a respiratory infection that is caused by inhaling the spores of the fungus Histoplasma capsulatum.
Histoplasma capsulatum, the fungus that causes histoplasmosis, 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 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, 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, elderly, and people with weakened immune systems, including those who:
Symptoms in these persons may include:
To diagnose histoplasmosis, the doctor needs to find the fungus or signs of the fungus in the body, or evidence that your immune system is reacting to the fungus.
Most cases of histoplasmosis clear up without specific treatment. Patients are advised to rest and take medication to control fever.
Your doctor may prescribe medication if you are sick for more than 4 weeks, have a weakened immune system, or are having breathing problems.
When histoplasmosis infection is severe or gets worse, the illness may last for one to six months. Even then, it is rarely fatal.
Acute pulmonary histoplasmosis can become chronic pulmonary histoplasmosis (which does not go away).
Histoplasmosis can spread from the lungs to other organs through the bloodstream. This type of spread is usually seen in infants, young children, and persons with a weakened immune system.
Acute pulmonary histoplasmosis can get worse over time, or can become chronic pulmonary histoplasmosis (which doesn't go away).
Histoplasmosis can spread to other organs through the bloodstream (dissemination). This is usually seen in infants, young children, and patients with a suppressed immune system.
Call your health care 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.
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Waht LJ, Freifeld AG, Kleiman MB, et al. Clinical practice guidelines for the management of patients with histoplasmosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis. 2007; 45(7):807-825.
Updated 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, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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