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What is Histoplasmosis?
Histoplasmosis is an infectious disease caused by inhaling spores of a fungus called Histoplasma capsulatum.

Who gets histoplasmosis?
Anyone who is present near dust-producing activities where material contaminated with H. capsulatum becomes airborne can get histoplasmosis if enough spores are inhaled. Infants, young children, and older persons, in particular those with chronic lung disease, are at increased risk for developing symptomatic histoplasmosis. People with weakened immune systems are at greatest risk for developing severe and disseminated disease.

H. capsulatum grows in soil throughout the world. In the United States, it is more common in the central and eastern states, especially along the valleys of the Ohio, Mississippi, St. Lawrence rivers, and the Rio Grande. The fungus seems to grow best in soils with a high nitrogen content, especially those contaminated with bird manure or bat droppings.

How is histoplasmosis spread?
Disturbances of contaminated material cause small spores of H. capsulatum to become airborne. Once airborne, spores can be easily carried by wind currents over long distances. People can become infected if they inhale these spores.

Histoplasmosis is not contagious; it cannot be transmitted from an infected person or animal to someone else.

What are the symptoms of histoplasmosis?
Histoplasmosis primarily affects a person's lungs, and its symptoms vary greatly. The vast majority of people have no apparent symptoms or their symptoms are so mild that they do not seek medical attention.

If symptoms do occur, they are similar to those of a mild, flu-like respiratory illness and may include fever, chest pain, dry (nonproductive) cough, headache, loss of appetite, shortness of breath, joint and muscle pain, chills and hoarseness.

The most severe and rare form of this disease is disseminated histoplasmosis, which involves spreading of the fungus to other organs outside the lungs.

How soon after exposure do symptoms appear?
Symptoms of disease usually start within 3 to 17 days after exposure, with an average of 10 days.

How is histoplasmosis diagnosed?
A person can learn from a histoplasmin skin test whether he or she has been previously infected with H. capsulatum. To diagnose histoplasmosis, a chest X-ray is needed.

What is the treatment for histoplasmosis?
Mild cases of histoplasmosis usually resolve without treatment. For severe cases, antifungal medications are needed. Disseminated histoplasmosis is fatal if untreated, but death can also occur in some patients even when medical treatment is received.

How can histoplasmosis be prevented?
The best way to prevent exposures to H. capsulatum spores is to avoid situations where material that might be contaminated can become aerosolized and subsequently inhaled. Since it is extremely difficult to know whether soil or bird droppings are contaminated, the safest approach is to assume that the soil in those parts of the country where H. capsulatum is common and any accumulations of bat droppings or bird manure are contaminated.

If materials that are potentially contaminated must be removed, contact your local health department for specific advice on how to protect yourself.

Where can I get more information?

UTAH DEPARTMENT OF HEALTH
BUREAU OF EPIDEMIOLOGY
August 2001

This fact sheet was based on the Centers for Disease Control and Prevention's Histoplasmosis: Protecting Workers at Risk guide (DHHS NIOSH Publication No. 97-146) (September 1997).