Histoplasma capsulatum

Histoplasmosis continues to cause significant morbidity and mortality, especially in the setting of increasing numbers of immunocompromised hosts. Fine-needle aspiration is a safe diagnostic technique that can yield a cytodiagnosis of histoplasmosis. The gold-standard diagnostic method in histoplasmosis is fungal isolation and identification in culture. Antigen detection tests may be more effective than antibody testing for diagnosing histoplasmosis. Antibody testing is most useful for subacute, chronic, and mediastinal forms of histoplasmosis, in which circulating antibodies are present and the sensitivity of antigen detection is suboptimal. In order to circumvent the limitations of histoplasmosis diagnosis, molecular biology techniques have been contributing to the development of approaches that indirectly detect H. capsulatum in clinical specimens by identifying specific nucleic acids, offering greater rapidity as compared to other diagnostics as well as high sensitivity and specificity, especially for AIDS patients. Antibodies to H. capsulatum can also be detected by immunoenzymatic assay such as Western blot.