Table 3.
Sensitivity of Quantitative Polymerase Chain Reaction, Microscopy, Immunoglobulin M (IgM) Trypomastigote Excreted-secreted Antigen Blot, and IgM Shed Acute-phase Antigen Test at Birth in the Diagnosis of Congenital Chagas Disease in the Training and Validation Cohorts
| Cohort | Testing at Birth | no./No. | % | (95% CI) |
|---|---|---|---|---|
| Training cohort | ||||
| Infected infants diagnosed at 0 or 1 mo (n = 26) | qPCR | 22/26 | 84.6 | (65.1–95.6) |
| Microscopy | 6/25 | 24.0 | (9.3–45.1) | |
| IgM-TESA blot | 18/25 | 72.0 | (50.6–87.9) | |
| IgM-SAPA test | 21/26 | 80.8 | (60.6–93.4) | |
| Infected infants diagnosed at 6–9 mo (n = 8) | qPCR | 0/8 | 0.0 | (.0–36.9) |
| Microscopy | 0/8 | 0.0 | (.0–36.9) | |
| IgM-TESA blot | 0/8 | 0.0 | (.0–36.9) | |
| IgM-SAPA test | 0/8 | 0.0 | (.0–36.9) | |
| All infected infants (n = 34) | qPCR | 22/34 | 64.7 | (46.5–80.3) |
| Microscopy | 6/33 | 18.2 | (7.0–35.5) | |
| IgM-TESA blot | 18/33 | 54.5 | (36.4–71.9) | |
| IgM-SAPA test | 21/34 | 61.2 | (43.6–77.8) | |
| Validation cohort | ||||
| Infants diagnosed at 0 or 1 month (n = 35) | qPCR | 34/35 | 97.1 | (85.1–99.9) |
| Microscopy | 19/35 | 54.3 | (36.6–71.2) | |
| IgM-TESA blot | 34/35 | 97.1 | (85.1–99.9) | |
| IgM-SAPA test | 33/35 | 94.3 | (80.8–99.3) | |
| Infants diagnosed from 6 to 9 mo (n = 8) | qPCR | 0/8 | 0.0 | (.0–36.9) |
| Microscopy | 0/3 | 0.0 | (.0–70.0) | |
| IgM-TESA blot | 0/7 | 0.0 | (.0–41.0) | |
| IgM-SAPA test | 0/8 | 0.0 | (.0–36.9) | |
| All infected infants (n = 43) | qPCR | 34/43 | 79.1 | (64.0–90.0) |
| Microscopy | 19/43 | 44.2 | (29.1–60.1) | |
| IgM-TESA blot | 34/43 | 79.1 | (64.0–90.0) | |
| IgM-SAPA test | 33/43 | 76.7 | (61.4–88.2) |
Abbreviations: CI, confidence interval; IgM-SAPA test, immunoglobulin M shed acute-phase antigen test; IgM-TESA blot, Western blot with trypomastigote excretory-secretory antigen for the detection of immunoglobulin M antibodies; qPCR, quantitative polymerase chain reaction.