Fungi can also invade internal organs of the body, especially the lungs, where the infections resemble pneumonia or pulmonary tuberculosis. Two fungi often found in such cases are Cryptococcus and Aspergillus, which are called opportunistic pathogens. The infectious agents Nocardia and Actinomyces, formerly classed as fungi, are now considered bacteria. Fungi belonging to the genus Candida, especially Candida albicans, can infect both internal organs and mucous membranes of the mouth, throat, and genital tract. In people with impaired immunity, this organism can cause a chronic infection.
Many drugs are available for treating fungal infections.
Persons chronically infected with Candida, Histoplasma, or Cryptococcus may require long-term therapy with an oral or an intravenous drug.