Finding the right tests…
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Finding the right tests…
ELISA
This test measures IgG antibodies against Aspergillus fumigatus, a marker of past or ongoing exposure to the mold rather than an allergic reaction. It is used mainly to help diagnose chronic pulmonary aspergillosis, a slow-developing lung infection that tends to occur in people with existing lung damage, such as old tuberculosis scarring or bronchiectasis. Unlike the IgE version of this test, which flags an allergic response, a raised IgG level suggests the immune system has been exposed to the fungus over time, often because it is colonising damaged lung tissue rather than causing a sudden infection. Doctors order it when someone with prior lung disease develops persistent cough, weight loss, or coughing blood that doesn't fit a straightforward bacterial infection.
The report gives an IgG level against Aspergillus fumigatus, read against the cutoff set by the assay used, since commercial kits vary noticeably in sensitivity and specificity. Studies comparing kits report sensitivity from roughly 58 to 96 percent and specificity from about 81 to 97 percent for chronic pulmonary aspergillosis, which is why a borderline result is often repeated or checked with a second method rather than treated as final. A positive result, with imaging showing a fungal ball or cavity, supports the diagnosis; a negative result with strong suspicion does not always rule it out.
This test looks for a different kind of immune response than the Aspergillus IgE test. IgG shows that your body has mounted a longer-term response to the fungus, consistent with the mold living in an existing lung cavity rather than triggering a short-lived allergic flare. That distinction is why this test sits in the diagnostic pathway for chronic pulmonary aspergillosis, not allergic bronchopulmonary aspergillosis.
People at meaningfully higher risk include those with a history of tuberculosis, since one study found chronic pulmonary aspergillosis in roughly six to thirteen percent of people with old tuberculosis lung damage, as well as people with bronchiectasis or other cavities from past lung disease. The test becomes the preferred first step precisely because other diagnostic routes are unreliable here - fungal cultures often come back negative even in true infection, and biopsy can be risky in someone whose lungs are already compromised.
Because commercial test kits vary in accuracy, some laboratories test IgG against more than one Aspergillus species, since combining results from two species, such as A. fumigatus and A. flavus, has been shown to improve how reliably the test catches true cases compared with testing one species alone.
IgG reflects longer-term exposure to the mold, often linked to it living in damaged lung tissue, while IgE reflects an allergic reaction. Doctors use IgG mainly for chronic pulmonary aspergillosis and IgE mainly for allergic bronchopulmonary aspergillosis.
Different commercial test kits vary in sensitivity, and studies show some miss a meaningful share of true cases. If your doctor's suspicion remains high based on imaging or symptoms, they may repeat the test or use a different method.
A result below the assay's cutoff is reported as negative, but the exact cutoff depends on which commercial kit the lab uses. Ranges vary by lab, so check the reference value on your own report.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
People with a history of tuberculosis, bronchiectasis, or another condition that left a cavity or scarring in the lung are most often tested, since chronic pulmonary aspergillosis develops mainly in already-damaged lungs.
There's no fixed fasting rule tied to this specific test. Ask your doctor or the centre when you book, since instructions can change if other tests are drawn from the same sample.
A positive result mainly reflects immune exposure to the fungus, so your doctor interprets it alongside imaging and symptoms rather than as proof of an active infection on its own.
Testing IgG against more than one species, rather than only Aspergillus fumigatus, has been shown to catch more true cases of chronic pulmonary aspergillosis than testing a single species alone.