Lung fungus, also known as aspergillosis, is an infection or allergic response caused by the fungus Aspergillus, according to MedlinePlus. Several forms of aspergillosis exist, including pulmonary aspergillosis and aspergilloma.
Pulmonary aspergillosis is an allergic bronchopulmonary reaction to the fungus in patients with pre-existing lung problems such as asthma or cystic fibrosis, states MedlinePlus. Aspergilloma is the growth of a fungus ball that develops in an area that experienced lung disease or lung scarring due to conditions such as tuberculosis or a lung abscess. Symptoms of aspergillosis include cough, fever, wheezing, weight loss, and coughing up blood or brownish mucus.