Molds are a type of fungus. They are all around us. Molds are common in soil, decaying food, air, and water. They cause little harm to most people. But when mold spores (tiny pieces of fungus) are breathed in, they can sometimes infect the lungs, sinuses, or other body organs. This is more likely if a person already has a serious illness or a weakened immune system (see What puts a person at risk for IFI due to molds? below).
Many different types of molds can infect the body. The most common type is called Aspergillus. It usually infects the lungs, but can also infect the sinuses, brain, or other organs. When Aspergillus causes serious infection, it is called aspergillosis or when found in the lungs, fungal pneumonia. Another type of mold that can cause serious infection is called Mucorales. When Mucorales cause serious infection, it is called mucormycosis.