Histoplasma Antibody Testing (Histoplasma Serology)
The antibody test for histoplasmosis is called Histoplasma serology or Histoplasma antibody testing, which detects antibodies against Histoplasma capsulatum using methods such as complement fixation (CF), immunodiffusion (ID), or enzyme immunoassay (EIA). 1
Specific Testing Methods Available
The antibody test encompasses several laboratory techniques:
Complement fixation (CF) detects antibodies against both mycelial and yeast antigens of Histoplasma capsulatum, with positivity in approximately 65.7% of culture-confirmed cases 2
Immunodiffusion (ID) identifies precipitin bands (M-band and H-band), with positivity in approximately 62.7% of culture-confirmed cases 2
Enzyme immunoassay (EIA) separately measures IgG and IgM antibodies, offering superior sensitivity of 88.8% compared to traditional methods 3
Clinical Performance Characteristics
In Immunocompetent Patients
Sensitivity ranges from 80-95% for pulmonary histoplasmosis 1
Specificity is excellent with less than 5% false-positive rate in endemic area residents outside outbreak periods 1
Critical Limitation in Immunocompromised Patients
Sensitivity drops dramatically to only 18% in organ transplant recipients 1
Sensitivity is only 45% in HIV/AIDS patients 1
Do not rely on antibody testing alone in immunocompromised patients—combine with antigen testing for optimal diagnostic yield 1
Timing Considerations
Antibodies take weeks to develop after initial exposure, making serology less useful for acute diagnosis 1
In acute pulmonary histoplasmosis, antigen testing becomes positive before antibody detection 1
Serial testing shows antibodies to mycelial antigen serorevert more frequently (55%) than antibodies to yeast antigen (15%) 2
Important Cross-Reactivity Issues
Cross-reactions occur with blastomycosis, coccidioidomycosis, paracoccidioidomycosis, and talaromycosis 1
Clinical correlation with exposure history and geographic location is essential for accurate interpretation 4
Optimal Diagnostic Strategy
Combining antibody EIA with antigen testing increases sensitivity to 96.3% in acute pulmonary histoplasmosis 3
For immunocompetent patients with suspected pulmonary histoplasmosis, order both Histoplasma serology and antigen testing simultaneously 1
For CNS disease, test CSF for both antibody (70-90% sensitivity) and antigen (40-70% sensitivity) 1