Placental Malaria Detected by Rapid Method

Evaluation of interventions to prevent malaria in pregnancy often relies on placental blood microscopy, which is time consuming and placental blood smears are difficult to read.

Rapid diagnostic tests (RDTs) based immunochromatographic test (ICT) are becoming the routine method for malaria diagnosis as they are easy and fast to use, and could be a good alternative to microscopy at the time of delivery.

Scientists at the University of Barcelona (Spain) working with colleagues in Mozambique, enrolled 1,151 pregnant women in a study from August 2006 to May 2008. Peripheral and placental blood smears were stained with Giemsa and examined according to standard, quality-controlled procedures. Placental blood samples were tested using the Plasmodium falciparum histidine-rich protein 2 HRP2-based RDT.

The prevalence of placental infection by microscopy and RDT were 5.1% and 5.0%, respectively, showing 82.9% agreement. Microscopy and RDT on placental blood agreed in 49 positive results and 1,083 negative results. Among the 1,092 placentas negative by microscopy, nine were positive by RDT. Among the 59 placentas positive by microscopy, 10 were negative by RDT, all corresponding to parasitemias below 500 parasites/µL. The RDT used in the study was a product of ICT Diagnostics (Cape Town, South Africa).

The authors concluded that the ICT HRP2-RDT assessed in their study can be a good alternative to placental microscopy in the diagnosis of placental malaria, facilitating its detection in settings with limited resources. However, some caution is required as when parasite densities are low placental infections can be missed. The study was published in the September 2012 issue of the Transactions of Royal Society of Tropical Medicine and Hygiene.

Related Links:
University of Barcelona
ICT Diagnostics