Histoplasmosis laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Serge Korjian M.D.
Overview
Laboratory Findings
- Histoplasma antigen detection in urine and/or serum is the most widely used and most sensitive method for diagnosing acute histoplasmosis.
Other methods include antibody tests, culture, and microscopy.
- Antigen detection: Enzyme immunoassay (EIA) is typically performed on urine and/or serum, but can also be used on cerebrospinal fluid or bronchoalveolar lavage fluid. Sensitivity is generally higher in urine than in serum, particularly for HIV-infected persons with disseminated histoplasmosis.
- Antibody tests: Because development of antibodies to Histoplasma can take two to six weeks, antibody tests are not as useful as antigen detection tests in diagnosing acute histoplasmosis or in immunosuppressed persons, who may not mount a strong immune response.
- Immunodiffusion (ID): Tests for the presence of H (indicates chronic or severe acute infection) and M (develops within weeks of acute infection and can persist for months to years after the infection has resolved) precipitin bands; ~80% sensitivity.
- Complement Fixation (CF): Complement-fixing antibodies may take up to 6 weeks to appear after infection. CF is more sensitive but less specific than immunodiffusion.
- Culture: can be performed on tissue and body fluids, but may take up to 6 weeks to become positive; most useful in the diagnosis of the severe forms of histoplasmosis.
- Microscopy: for detection of budding yeast in tissue or respiratory secretions; low sensitivity.
- Polymerase Chain Reaction (PCR): PCR for detection of Histoplasma directly from clinical specimens is still experimental, but promising.[1]
References
- ↑ Information for Healthcare Professionals about Histoplasmosis. Centers for Disease Control and Prevention. 2015. Available at: http://www.cdc.gov/fungal/diseases/histoplasmosis/health-professionals.html. Accessed February 2, 2016.