TABLE 3.
Naive sensitivity of IgM ELISA estimated in those in the study cohort who had a positive blood culture, a combination of PCR assays positive, or the presence of an eschar and in those who had a final diagnosis of either murine typhus or dengue infection
| Population | No. with IgM ELISAa positive | Naive sensitivity (%) | No. with IgM ELISAa negative | Naive specificity (%) |
|---|---|---|---|---|
| Patients who had blood culture positive (n = 7) | 5 | 71.4 (5/7) | NA | NA |
| Patients who had a combination of PCR assays positiveb (n = 22) | 17 | 77.3 (17/22) | NA | NA |
| Patients with the presence of an eschar (n = 14) | 11 | 78.6 (11/14) | NA | NA |
| Overallc (n = 29) | 20 | 69.0 (20/29) | NA | NA |
| Patients with a final diagnosis of murine typhus (n = 8) | NAd | NA | 8 | 100 (8/8) |
| Patients with a final diagnosis of dengue (n = 19) | NA | NA | 18 | 94.7 (18/19) |
| Overall (n = 27) | NA | NA | 26 | 96.3 (26/27) |
a
IgM ELISA was defined as positive when the OD was ≥1.474 at a sample dilution of 1:400 for either the admission or the convalescent/discharge sample.
b
A combination of PCR assays was defined as positive when at least two out of the three PCR assays (56-kDa nPCR assay, 47-kDa-based qPCR assay, and groEL-based qPCR assay) were positive.
c
Patients who had blood culture positive, a combination of PCR assays positive, or the presence of an eschar.
d
NA, not applicable.