What causes Aspergillosis?
Aspergillus enters the body when you breathe in the fungal spores (“seeds”). This fungus is commonly found in your lungs and sinuses. If your immunity (the ability to “!ght off” infections) is normal, the infection can be contained and may never cause an illness. However, a weak immune system or having a chronic lung disease allows the Aspergillus to grow,  invade your lungs and spread throughout your body.
This may happen if you:

• have a cancer such as leukemmia or aplastic anemia
• take chemotherapy or are on corticosteroids for a long term
• had an organ transplant (kidney or lung)
• have advanced HIV infection 
• have a chronic lung disease like asthma, emphysema, tuberculosis or cystic fibrosis.

Aspergillosis is a disease caused by a fungus (or mold) that is very common in the environment

Aspergillosis is a disease caused by a fungus (or mold) that is very common in the environment. There are different kinds of aspergillosis. One kind is allergic bronchopulmonary aspergillosis (also called ABPA). Symptoms of ABPA include wheezing and coughing. ABPA can affect healthy people but it is most common in people with asthma or cystic fibrosis.

Another kind is invasive aspergillosis, which invades and damages tissues in the body. It usually affects the lungs, but it can also cause infection in other organs and spread throughout the body. It affects people who have immune system problems, such as people who have had a transplant, are taking high doses of steroids, or getting chemotherapy for some cancers.

Your doctor might do a variety of tests to make the diagnosis, including a chest x-ray, CT scan of the lungs, or examining tissues for signs of the fungus. Treatment is with antifungal drugs.

Centers for Disease Control and Prevention