Histoplasma Antibody Immunodiffusion

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• The Histoplasma Antibody Immunodiffusion test is used for the in vitro determination of precipitating antibodies to Histoplasma sp. It is also used as an aid in the diagnosis of Histoplasmosis.
• This test detects the presence of two significant precipitin bands. Presence of both the H and the M band indicates active histoplasmosis. The presence of the M band alone indicates early or chronic disease. The M band may also be present following a recent histoplasmin skin test.

Fungal Immunodiffusion

The result is not intended to be used as the sole means for clinical diagnosis or patient management decisions.

• Negative serologic tests may be observed among culturally demonstrable cases, which limits the predictive value of a negative test.
• Negative serologic results obtained during the first month may warrant repeat testing.
• Falsely negative results may be obtained when testing immunocompromised patients.
• Test results cannot be used solely, to distinguish between active infection and prior exposure.

Cross Reactivity/False Positive: moderate to low: Blastomyces, Histoplasma, Coccidioides, Aspergillus

Testing is performed on Tuesdays and Fridays.

Results released: Positive: 24 hours; Negative: 72 hours

*New positives may require confirmation

• Antibody not detected
• Will report H and M bands

• Negative: Antibody not detected
• Positive: Antibody detected

Specimen:  Serum, CSF*, Plasma*
*Uncommon specimen includes incomplete validation. A ’rare specimen’ note will appear on the final report.

Container:
Serum: Collect serum specimens in serum separator tube. Allow blood to clot for 30 minutes, then centrifuge. Send serum in serum separator tube or transfer tube.
CSF, Plasma: Separator or transfer tube
Volume:  0.25 mL
Stability:  Room temperature = 28 days, Refrigerated = 6 months, Frozen = indefinite

Any specimen types other than serum.

Refrigerated/Frozen

Overnight-with cold pack.