Aspergillosis might sound like a complicated word, but it's an infection caused by a mold called Aspergillus. This mold is everywhere – you can find it indoors and outdoors. Most of the time, it doesn't cause any harm. But for some people with weakened immune systems or certain lung conditions like asthma, it can lead to serious illnesses. Invasive Aspergillosis is a serious type of Aspergillosis.