This is caused by Histoplasma capsulatum. H. capsulatum is endemic in many parts of the world including North and South America. It is found in the soil and growth is enhanced by the presence of bird and bat excreta. Environments containing such material are often implicated as sources of human infection. The lungs are the main site of infection but dissemination to the liver, heart and central nervous system can occur.
Pulmonary infection can resemble symptoms seen in tuberculosis.
Here, patients usually have some serious immune or metabolic defect, or have undergone surgery. The diseases include aspergillosis, systemic candidosis and cryptococcosis. Exceptionally, other fungi that are normally not pathogenic, such as Trichosporon, Fusarium or Penicillium, may cause systemic infections. This is the name given to a number of different diseases caused by the mould Aspergillus. It produces large numbers of spores and occurs world-wide.