IgG antibodies to Blastomyces antigen appear to be associated with active infection, especially in dogs with moderate to high positive (20 EU or greater) results. Antibodies may also be detected in a small percentage of healthy dogs as a result of sub-clinical infection within the last 2 years; however, results of preliminary studies show high specificity of the assay (>90%) in healthy animals from Blastomyces-endemic areas. IgG may be detected in blastomycosis cases with false-negative antigen results (especially with localized disease; e.g., ocular or bone infections) and combined antibody and antigen testing increases the overall sensitivity. Intermediate results (8-9.9 EU) typically reflect either rising or falling IgG, and retesting the patient in several weeks may be beneficial.
Semi-Quantitative Indirect Enzyme Immunoassay (EIA)
Cross Reactivity/False Positive: Moderate to Low: Blastomyces, Histoplasma, Coccidioides
Testing is performed Wednesday and Friday
Results released: Positive: 24 hours; Negative: 72 hours
Negative: <8.0 EU
Intermediate: 0 EU – 9.9 EU
Positive: 0 EU – 80.0 EU
Positive Above the Limit of Quantification: >80.0 EU
Specimen: Serum, CSF*, Plasma*
*Uncommon specimen includes incomplete validation. A ’rare specimen’ note will appear on the final report.
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: Sterile transport tube
Anticoagulant: Heparin, EDTA, NaCit
Volume: 0.25 mL
Stability: Room Temperature=28 days, Refrigerated=6 months, Frozen=indefinite
Ship overnight or 2nd day -ambient or with cold pack