What Is Allergic Bronchopulmonary Aspergillosis (ABPA)?

Aspergillus is a type of fungus (also referred to as a mold), that is commonly found in the environment. It can be found in the soil, dust, water, and rotting or decaying vegetation (like dead leaves or compost piles), marijuana, and some foods and ground spices. The fungus forms into spores which are very small particles that can float in the air. Most people inhale its spores from the air, but do not have any problems from being exposed. In most cases, the fungus can live in the mucus in the breathing tubes (airways). This is called colonization. Having Aspergillus in your airways does not mean you have or will have a sudden (acute), and serious infection by this fungus. Our immune system usually helps protect the body from infections like these. In some people who have a weakened immune system, Aspergillus can get into the lungs, causing an acute infection. (For more about Aspergillus infection, see the ATS Patient Information Series fact sheet: Aspergillosis in the Fungal Disease Series). However, in a few cases, this exposure to Aspergillus triggers an allergic immune response without invading the tissues that leads to ABPA (allergic bronchopulmonary aspergillosis).