Table 1.
Performance and considerations for coccidioidomycosis laboratory diagnostic tests.
| Test | Sensitivity | Specificity ‡ | Considerations |
|---|---|---|---|
| Serology | |||
| Antibody | Antibody production may lag behind symptom onset. Sensitivity is often lower in immunosuppressed patients. |
||
| EIA IgG or IgM [103,104,105] | 59–88% | 68–96% | Rapid performance time within hours. Often used as a screening test, later confirmed by ID or CF. IgM only may lead to more false positives than IgG only. |
| EIA IgG [103,104,105] | 47–87% | 89–97% | |
| EIA IgM [103,104,105] | 22–61% | 70–99% | |
| ID § [103,118] | 60–91% | 99–100% | Results may take several days to receive. Some specialized training is required. Methods are not standardized across laboratories. |
| CF § [103,108,109,118] | 65–98% | 80–98% | Titers may offer prognostic value of disease progression. Measurement of IgG only. Highly specialized training is required. Methods are not standardized across laboratories. |
| LFA § [117,118] | 31–99% | 92–98% | Rapid 1-h performance time. |
| Antigen | |||
| Urine and serum [113] | 57% | 99% | May detect Coccidioides in the early stages of the disease [112]. May be preferred to antibody tests for immunocompromised patients. Substantial cross-reactivity with other dimorphic fungi. |
| Urine [111,113] | 37–71% | 99% | |
| Serum [119] | 73% | 100% | |
| Microscopy and culture | |||
| Culture [114] | 23–93% | High | Considered the gold standard of coccidioidomycosis diagnosis. Biosafety level 3 lab needed for safe isolation of Coccidioides. Culture growth may take up to a week. Sensitivity is heavily dependent on specimen quality. |
| Histopathology [114] | 23–84% | High | |
| Cytology [114] | 15–75% | High | |
| Additional laboratory methods | |||
| PCR [115,116] | 56–75% | 99–100% | Rapid 4-h performance time. Site of specimen collection may influence results. |
| (1→3) β-d-glucan [117] | 44% | 91% | Lower sensitivity among patients with acute pulmonary coccidioidomycosis. Values correlate poorly with CF titers. Test cannot detect specific pathogens. |
Abbreviations: CF, complement fixation; EIA, enzyme immunoassay; ID, immunodiffusion; IgG, immunoglobulin G; IgM, immunoglobulin M; PCR, polymerase chain reaction. ‡ Specificity is based on published results; estimates may not be directly comparable, as different control populations were used in some cases. § Sensitivity and specificity ranges include testing from outbreak investigations.