Aspergillus is a type of fungus that is very common in the environment. It is found in soil, on plants, and in the air. Aspergillus can enter the lungs when a person breathes in spores from the air. Once inside the lungs, the spores can cause infection.
The prevalence of Aspergillus in the lungs is not well understood, but it is thought to be fairly common. A study published in the journal Chest in 2018 found that Aspergillus was present in the airways of about 10% of healthy people, as well as in the airways of nearly 20% of people with asthma. This suggests that Aspergillus is relatively common in the lungs.
In addition, Aspergillus is a major cause of hospital-acquired pneumonia, and is estimated to account for about 5% of all cases of hospital-acquired pneumonia. Aspergillus infection can also occur in people with compromised immune systems, such as those with HIV, and is estimated to account for up to 20% of cases of pneumonia in this population.
Overall, it appears that Aspergillus is fairly common in the lungs, particularly in those with asthma and weakened immune systems. It is important for people with these conditions to be aware of the potential for Aspergillus infection, and to take steps to protect themselves from infection.