Aspergillosis is an infection, growth, or allergic response due to the Aspergillus fungus.

Aspergillosis is caused by a fungus (Aspergillus), which is commonly found growing on dead leaves, stored grain, compost piles, or in other decaying vegetation. It can also be found on marijuana.

Although most people are frequently exposed to aspergillus, infections caused by the fungus rarely occur in people with a normal immune system. The rare infections caused by aspergillus include pneumonia and fungus ball (aspergilloma).

There are several forms of aspergillosis:

• Pulmonary aspergillosis - allergic bronchopulmonary type -- is an allergic reaction to the fungus that usually develops in people who already have lung problems (such as asthma or cystic fibrosis).
• Aspergilloma -- is a growth (fungus ball) that develops in an area of previous lung disease or lung scarring (such as tuberculosis or lung abscess).
• Pulmonary aspergillosis - invasive type -- is a serious infection with pneumonia that can spread to other parts of the body. This infection occurs almost exclusively in people with weakened immune systems due to cancer, AIDS, leukemia, organ transplantation, chemotherapy, or other conditions or medications that lower the number of normal white blood cells or weaken the immune system.