Histoplasmosis is an infection caused by breathing in spores of a fungus often found in bird and bat droppings. Histoplasmosis is most commonly transmitted when these spores become airborne, often during cleanup or demolition projects.
Soil contaminated by bird or bat droppings also can transmit histoplasmosis, so farmers and landscapers are at a higher risk of contracting the disease. In the United States, histoplasmosis commonly occurs in the Mississippi and Ohio river valleys, though it can occur in other areas, too.
Most people with histoplasmosis never develop symptoms and aren't aware they're infected. But for some people — primarily infants and those with compromised immune systems — histoplasmosis can be serious. Effective treatments are available for even the most severe forms of histoplasmosis.