A certain percentage of bat populations are infected with a virus called Capsulatum Cistoplasme and can consequently excrete the organism in their droppings. As a result of this, accumulations of bat guano (droppings), especially in interior spaces, may pose significant health risks to individuals exposed to airborne particles.

Anyone exposed to contaminated material such as bat droppings or insulation contaminated by bat droppings, can develop Histoplasmosis. Histoplasmosis is an infectious disease caused by inhaling the spores of the fungus. The symptoms of histoplasmosis vary in severity from flu-like symptoms, to chronic lung disease, to blindness and even death in rare cases.