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1. What is histoplasmosis?

Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. This fungus grows in soil, especially soil contaminated with bird or bat droppings. Its symptoms vary greatly, but the disease primarily affect the lungs. Histoplasma capsulatum is found throughout the world and in the United States where this organism is more prevalent in the soil.

2. How histoplasmosis is spread?

Histoplasmosis is not spread from person to person. Infection occurs from breathing in the airborne spores after contaminated soil or material has been disturbed. Approximately 80% of the population living in areas along rivers and farmland may skin-test positive for histoplasmosis exposure.

3. What are the symptoms of histoplasmosis?

Most infected persons have no apparent illness. If symptoms occur, they will start within 3 to 17 days after exposure. Persons developing disease usually present with an influenza-like illness with fever, cough, headaches, and muscle aches. Acute pneumonia, chronic pneumonia, or a disseminated form that affects other organs can occur. Histoplasmosis can be a fatal illness if persons exhibiting disease symptoms are not treated.

4. How is histoplasmosis diagnosed?

Histoplasmosis is diagnosed by a variety of laboratory tests that either isolate the organism or detect antigens of the organisms in either blood serum or urine. Chest x-rays will show distinct patterns and the chronic form can resemble tuberculosis. The histoplasmin skin test denotes exposure but does not indicate disease and is not a diagnostic test.

5. Is histoplasmosis treatable?

Yes. Antifungal medications are used to treat severe cases of acute, chronic, and disseminated disease. Mild disease usually does not require treatment. Past infection results in partial protection against ill effects if reinfected.

6. How can histoplasmosis be prevented?

It is not practical to test or decontaminate most sites that may be contaminated with H. capsulatum, but avoid areas that may harbor the fungus, such as:

• Accumulation of bird or bat droppings
• Poultry house litter
• Caves, areas harboring bats
• Bird roosts

Before starting a job or activity having a risk for exposure to H. capsulatum, consult the National Institute for Occupational safety and Health's document Histoplasmosis: Protecting Workers at Risk. This document contains information on work practices and personal protective equipment that will reduce the risk of infection. A copy can also be obtained by requesting publication No. 97-146 from the:
National Institute for Occupational Safety and Health

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