TABLE 3.
Results of Zika NS1 BOB ELISA in early and late convalescent-phase samples for diagnosis and surveillance of ZIKV infectionsa
| Patient population | NS1 BOB ELISA |
|||
|---|---|---|---|---|
| Early convalescence |
Late convalescence |
|||
| Sens (95% CI) | Spec (95% CI) | Sens (95% CI) | Spec (95% CI) | |
| Overall | 85.0 (77.6–90.7) | 91.4 (86.2–95.1) | 96.5 (91.2–99.0) | 92.6 (87.2–96.3) |
| ZIKV positive | 85.0 (77.6–90.7) | NA | 96.5 (91.2–99.0) | NA |
| DENV naïve | 77.4 (65.0–87.1) | NA | 98.3 (90.8–100.0) | NA |
| DENV immune | 92.3 (83.0–97.5) | NA | 94.5 (84.9–98.9) | NA |
| DENV positive | NA | 88.7 (80.6–94.2) | NA | 90.0 (81.2–95.6) |
| DENV1 | NA | 95.8 (78.9–99.9) | NA | 85.0 (62.1–96.8) |
| DENV2 | NA | 85.3 (68.9–95.0) | NA | 89.7 (72.2–97.8) |
| DENV3 | NA | 87.2 (72.6–95.7) | NA | 93.5 (78.6–99.2) |
| Primary | NA | 100.0 (92.6–100.0) | NA | 89.5 (75.2–97.1) |
| Secondary | NA | 77.6 (63.4–88.2) | NA | 90.5 (77.4–97.3) |
| Negative | NA | 94.8 (87.2–98.6) | NA | 95.7 (87.8–98.1) |
Sens, sensitivity. Sensitivity values were calculated for each assay based on ZIKV-positive samples, stratified by those who had been previously infected with DENV (DENV immune) and those who were DENV naïve. Spec, specificity. Specificity values were calculated for each assay based on two groups of ZIKV-negative samples: (i) ZIKV-negative DENV-positive samples, stratified by DENV subtype (DENV1 to DENV3) and primary and secondary infection, and (ii) ZIKV-negative DENV-negative controls. 95% CI, 95% confidence interval. NA, not applicable: data from ZIKV-positive cases served only for determination of sensitivity and were not used for the specificity calculation. Similarly, data from ZIKV-negative cases served only for determination of specificity and were not used for the sensitivity calculation.