How well did a rapid malaria test detect infections during pregnancy?

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Intermittent screening and treatment in pregnancy (ISTp) is a potential strategy for controlling malaria during pregnancy, but the frequency and consequences of infections missed by a malaria rapid diagnostic test (RDT) are a concern.

Women in their first or second pregnancy who participated in the ISTp arm of a noninferiority trial in four West African countries were screened with an HRP2/pLDH RDT at enrollment and, in Ghana, at subsequent antenatal clinic (ANC) visits. Blood samples were subsequently examined by microscopy and a polymerase chain reaction (PCR) assay.

At enrollment, RDT sensitivity for detecting peripheral blood infections confirmed by microscopy and/or PCR ranged from 91% (95% confidence interval [CI], 88%–94%) in Burkina Faso to 59% (95% CI, 48%–70%) in The Gambia. In Ghana, sensitivity was 89% (95% CI, 85%–92%) at enrollment, 83% (95% CI, 76%–90%) at the second ANC visit and 77% (95% CI, 67%–86%) at the third, but only 49% (95% CI, 31%–66%) at delivery. Screening at enrollment detected 56% of all infections detected throughout pregnancy.

Among 540 women, 75 infections were RDT-negative but positive by PCR or microscopy; these infections were not associated with maternal anemia, placental malaria or low birth weight. The researchers concluded that RDT sensitivity was high at enrollment in three of the four countries and at subsequent ANC visits in Ghana. In Ghana, RDT-negative malaria infections were not associated with adverse birth outcomes, but missed infections were uncommon.