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Test ID: BLAST Blastomyces Antibody, Enzyme Immunoassay, Serum

Reporting Name

Blastomyces Ab, EIA, S

Useful For

Aiding in the diagnosis of blastomycosis

Clinical Information

Blastomyces dermatitidis, an adimorphic fungus, is endemic throughout the Midwestern, south-central, and southeastern Unites States, particularly in regions around the Ohio and Mississippi river valley, the Great Lakes and the Saint Lawrence River. It is also found in regions of Canada. Blastomyces is an environmental fungus, preferring moist soil and decomposing organic matter, which produces fungal spores that are released and inhaled by animals or humans. At body temperature, the spores mature into yeast, which can stay in the lungs or disseminate through the bloodstream to other parts of the body. Recently, through phylogenetic analysis, Blastomyces dermatitidis has been separated into two distinct species; B. dermatitidis and Blastomyces gilchristii, both able to cause blastomycosis in infected patients. Interestingly, B. dermatitidis infections are associated more frequently with dissemination, particularly in elderly patients, smokers and immunocompromised hosts, while B. gilchristii has primarily been associated with pulmonary and constitutional symptoms.


Approximately 50% of patients infected with Blastomyces will develop symptoms, which are frequently non-specific and, include fever, cough, night sweats, myalgia or arthralgia, weight loss, chest pain and fatigue. Typically symptoms appear anywhere from 3 weeks to 3 months following infection.


Diagnosis of blastomycosis relies on a combination of assays, including culture and molecular testing on appropriate specimens and serologic evaluation for both antibodies to and antigen released from Blastomyces. Although culture remains the gold standard method and is highly specific, the organism can take several days to weeks to grow, and sensitivity is diminished in cases of acute or localized disease. Similarly, molecular testing offers high specificity and a rapid turnaround time, however, sensitivity is imperfect. Detection of an antibody response to Blastomyces offers high specificity, however, results may be falsely negative in acutely infected patients and in immunosuppressed patients.


A positive result indicates that IgG and/or IgM antibodies to Blastomyces were detected. The presence of antibodies is presumptive evidence that the patient was or is currently infected with (or was exposed to) Blastomyces.


A negative result indicates that antibodies to Blastomyces were not detected. The absence of antibodies is presumptive evidence that the patient was not infected with Blastomyces. However, the specimen may have been obtained before antibodies were detectable or the patient may be immunosuppressed. If infection is suspected, another specimen should be collected 7 to 14 days later and submitted for testing.


Specimens testing positive or equivocal will be submitted for further testing by another conventional serologic test (eg, SBL / Blastomyces Antibody by Immunodiffusion, Serum).

Report Available

1 to 3 days

Day(s) Performed

Monday through Friday

Clinical Reference

Kaufman L, Kovacs JA, Reiss E: Clinical immunomycology. In: Rose NR, De Macario EC, Folds JD, et al, eds. Manual of Clinical and Laboratory Immunology. ASM Press; 1997:588-589

Method Name

Enzyme Immunoassay (EIA)

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Reference Values


Reference values apply to all ages.

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
BLAST Blastomyces Ab, EIA, S 7816-2


Result ID Test Result Name Result LOINC Value
BLAST Blastomyces Ab, EIA, S 7816-2

Testing Algorithm

If result is equivocal or positive, Blastomyces antibody by immunodiffusion will be ordered at an additional charge.


See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
SBL Blastomyces Ab, Immunodiffusion, S Yes, (SBL) No


If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.

Mayo Clinic Laboratories | Microbiology and Infectious Disease Catalog Additional Information: