Understanding Histoplasmosis

What is Histoplasmosis?

Histoplasmosis is a lung infection caused by inhaling the spores of a fungus. This fungus, called Histoplasma capsulatum, is common in most of the central and eastern United States. The fungus grows in soil, as well as bird and bat droppings, and is spread by breathing in the spores of disturbed soil.

Occupations and hobbies that carry risks for exposure to the fungus include:

  • Bridge inspector or painter
  • Chimney cleaner
  • Construction worker
  • Demolition worker
  • Farmer
  • Gardener
  • Heating and air-conditioning system installer or service person
  • Microbiology laboratory worker
  • Pest control worker
  • Restorer of historic or abandoned buildings
  • Roofer
  • Spelunker (cave explorer)

How Serious is Histoplasmosis?

Many histoplasmosis infections do not produce symptoms. The illness occurs in two forms. The acute form is much like a mild case of influenza and is rarely serious.

The chronic form, which is much less common, may resemble tuberculosis. In rare cases, the disease will spread throughout the body. This is most likely to happen in the very young, the very elderly and people with impaired immune systems, including people with cancer and AIDS. If histoplasmosis has spread, it can be life-threatening if it is not treated. People who have a chronic lung disease, such as COPD, are at higher risk of a more severe infection.