Comparison of placental blood microscopy and the ICT HRP2 rapid diagnostic test to detect placental malaria

Monitoring interventions to prevent malaria in pregnancy requires sensitive detection of placental infection. Rapid diagnostic tests (RDTs) are good candidates, but little information is available on their sensitivity on placental blood. We have evaluated the agreement (kappa coefficient) between microscopy and a Plasmodium falciparum histidine-rich protein 2 (HRP2)-based immuno-chromatographic test (ICT) on placental blood from 1151 women at delivery. Prevalences of placental infection by microscopy and RDT were 5.1% and 5.0%, respectively, showing 82.9% agreement (p<0.0001). Discordances were found at low parasitemias (<500 parasites/μL) or negative microscopy. The results suggest that the HRP2-RDTs from ICT diagnostics is a good alternative to microscopy for diagnosing placental malaria at delivery.