Histoplasmosis, among the endemic mycoses, is the leading cause for hospitalization and death in the USA. The infection is asymptomatic in most otherwise healthy individuals who experience low inoculum exposure, but may cause severe pneumonia following a heavy exposure. Patients with underlying obstructive pulmonary disease typically develop chronic pulmonary disease, which is progressive if not treated. Progressive disseminated disease may occur, usually in patients with underlying immunocompromised, and is generally fatal if not diagnosed and treated correctly.
The diagnosis can be established without difficulty in most patients by use of a battery of mycologic and serologic tests. Antigen detection is the most sensitive method for diagnosing acute diffuse pulmonary histoplasmosis, and progressive disseminated histoplasmosis. Serologic tests are helpful, particularly in patients with mild acute pulmonary and subacute pulmonary histoplasmosis.
Treatment is indicated in most patients with acute diffuse pulmonary histoplasmosis and all patients with chronic pulmonary histoplasmosis or progressive disseminated histoplasmosis. Liposomal amphotericin B is the treatment of choice for patients with severe manifestations of histoplasmosis requiring hospitalization. Itraconazole is recommended for mild cases not requiring hospitalization and for continued therapy following response to liposomal amphotericin B.
Disclaimer: Dr. Wheat is the president of MiraVista Diagnostics, the company that developed and performs histoplasma antigen testing. Dr. Hage is an assistant professor of medicine at Indiana University School of Medicine and faculty in the thoracic transplantation program at Indiana University Health.