A person with pneumonia has inflammation of the small air passageways and alveoli in the lung, usually due to an infection.

Fungal pneumonia is caused by overgrowth of the fungi in the lungs. Fungal lung infections are usually only seen in those with a poorly functioning immune system, such as those with AIDS.

Fungi are plant-like organisms that do not make chlorophyll. Common examples include mushrooms, yeasts, and molds. Fungi are normally present on the skin. An overgrowth of fungi can cause common skin infections, such as athlete's foot and jock itch.