page_title: Histoplasmosis
section_title: Diagnosis
hierarchical_section_title: Histoplasmosis / Diagnosis
caption_attribution_description: English: This chest film shows diffuse pulmonary infiltration due to acute pulmonary histoplasmosis caused by H. capsulatum.
context_page_description: Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; this is called disseminated histoplasmosis, and it can be fatal if left untreated.
  Histoplasmosis is common among AIDS patients because of their suppressed immunity. In immunocompetent individuals, past infection results in partial protection against ill effects if reinfected.
  Histoplasma capsulatum is found in soil, often associated with decaying bat guano or bird droppings. Disruption of soil from excavation or construction can release infectious elements that are inhaled and settle into the lung.
  From 1938 to 2013, a total of 105 U.S. outbreaks were reported in 26 states and the territory of Puerto Rico. From 1978 to 1979, during a large urban outbreak of the disease in Indianapolis, victims had pericarditis, rheumatological syndromes, esophageal and vocal cord ulcers, parotitis, adrenal insufficiency, uveitis, fibrosing mediastinitis, interstitial nephritis, intestinal lymphangiectasia, and epididymitis.
context_section_description: Clinically, there is a wide spectrum of disease manifestation, making diagnosis somewhat difficult. More severe forms include: (1) the chronic pulmonary form, often occurring in the presence of underlying pulmonary disease; and (2) a disseminated form, which is characterized by the progressive spread of infection to extra-pulmonary sites. Oral manifestations have been reported as the main complaint of the disseminated forms, leading the patient to seek treatment, whereas pulmonary symptoms in disseminated disease may be mild or even misinterpreted as flu. Histoplasmosis can be diagnosed by samples containing the fungus taken from sputum (via bronchoalveolar lavage), blood, or infected organs.  It can also be diagnosed by detection of antigens in blood or urine samples by ELISA or PCR. Antigens can cross-react with antigens of African histoplasmosis (caused by Histoplasma duboisii), blastomycosis, coccidioidomycosis, paracoccidioidomycosis, and talaromycosis infection. Histoplasmosis can also be diagnosed by a test for antibodies against Histoplasma in the blood.  Histoplasma skin tests indicate whether a person has been exposed, but do not indicate whether they have the disease. Formal histoplasmosis diagnoses are often confirmed only by culturing the fungus directly. Sabouraud agar is one type of agar growth media on which the fungus can be cultured. Cutaneous manifestations of disseminated disease are diverse and often present as a nondescript rash with systemic complaints. Diagnosis is best established by urine antigen testing, as blood cultures may take up to 6 weeks for diagnostic growth to occur and serum antigen testing often comes back with a false negative before 4 weeks of disseminated infection.
caption: Chest X-ray of a patient with acute pulmonary histoplasmosis
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