Only a small group of fungi have been associated with infectious disease. Aspergillosis is an infectious disease that can occur in immune-suppressed persons. Health effects in this population can be severe. Several species of Aspergillus are known to cause aspergillosis. The most common is Aspergillus fumigatus. But exposure to this common mold, even in high concentrations, is unlikely to cause infection in a healthy person.
Breathing in mold may also cause hypersensitivity pneumonitis, an uncommon disease that resembles bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose immune systems are weakened or suppressed.
There are fungal infections that can affect healthy people. They are pathogenic fungi sometimes found inside a building: Blastomyces (which inhabit decaying wood); Coccidioides (found in the southwestern United States); Cryptococcus (in bird droppings); and Histoplasm a (in bat guano or droppings). People without adequate personal protection equipm ent (PPE) who come in contact with bird or bat droppings, such as may be found in attics, could be at very high risk. People with compromised immune systems can be seriously affected by fungal infections.
Exposure to fungi associated with bird and bat droppings (Histoplasm a capsulatum and Cryptococcus neoform ans) can lead to negative health effects in healthy individuals, usually in the form of transient flu-like illnesses. Severe health effects are primarily encountered in immune-com promised persons. People with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.