RESUMO
OBJECTIVE: The testing of neonatal blood specimens dried on filter paper for maternal HIV antibodies, using an enzyme immunoassay (EIA) with confirmation of repeatedly reactive specimens by immunoblot (IB), was first described in 1987. It has been used to conduct large, unlinked, anonymous HIV seroprevalence surveys for surveillance of HIV in child-bearing women in several countries. We directly assessed the sensitivity and specificity of this combination of tests to detect maternal HIV antibodies. SETTING: Serum samples obtained from mothers delivering at a major hospital in Kinshasa, Zaire were screened for HIV antibody using the rapid assay HIVCHEK. DESIGN: Plasma from HIVCHEK-positive women and age-matched negative controls were tested by enzyme-linked immunosorbent assay (ELISA); repeatedly reactive specimens were confirmed by Western blot (WB). Two days after delivery, whole blood was obtained from each newborn by heel-stick, dried on filter paper, and tested by EIA. Repeatedly reactive specimens were confirmed by IB. MAIN OUTCOME MEASURE: The serologic status of neonatal filter-paper specimens was compared with that of corresponding maternal plasma. RESULTS: The testing of neonatal filter-paper specimens using EIA, with confirmatory testing of repeatedly reactive specimens using IB, was 100.0% sensitive [of the 192 ELISA-positive and WB-positive maternal plasma specimens, 192 of the corresponding newborn filter-paper specimens were EIA-positive and IB-positive; 95% confidence interval (CI), 98.1-100]. The detection of maternal HIV antibodies was 99.6% specific using this combination of tests (of the 281 ELISA-negative or ELISA-positive but WB-negative maternal plasma samples, 280 of the corresponding newborn filter-paper specimens were EIA-negative or EIA-positive but IB-negative; 95% CI, 98.0-100). CONCLUSIONS: Maternal HIV antibodies can be detected accurately by testing neonatal blood dried on filter paper, using EIA with confirmation of repeatedly reactive specimens by IB. This approach can facilitate the determination of HIV seroprevalence in child-bearing women in countries with neonatal screening programs, or where serum or plasma is difficult to obtain.
PIP: Neonatal blood specimens dried on filter paper have been tested for maternal HIV antibodies in large, unlinked, anonymous HIV seroprevalence surveys toward the surveillance of HIV in child-bearing women in several countries. This study assesses the sensitivity and specificity of this combination of tests. The standard approach involves first testing the sample via an enzyme immunoassay (EIA), then confirming repeatedly reactive specimens through immunoblot (IB). To test this methodology, serum samples were obtained from mothers delivering at a major hospital in Kinshasa, Zaire, and screened with rapid assay HIVCHEK for antibody to HIV. Plasma from HIVCHEK-positive women and age-matched negative controls were then subjected to ELISA, with repeatedly reactive samples confirmed with Western blot. Whole blood was later obtained by heel-stick from each newborn 2 days after delivery, dried on filter paper, and tested by EIA and IB for confirmation. The serologic statuses of neonatal filter-paper specimens were then compared with those of corresponding maternal plasma. 100% sensitivity was achieved by testing neonatal filter-paper specimens with EIA and confirming with IB. The combination of tests also proved 99.6% specific for detecting maternal HIV antibodies; both results are at 95% confidence intervals. These results demonstrate that maternal HIV antibodies can therefore be detected accurately by testing neonatal blood dried on filter paper, using EIA, then confirming repeatedly reactive specimens via IB. This approach may help determine HIV seroprevalence in childbearing women in countries with neonatal screening programs or where serum or plasma is difficult to obtain.
