Placental malaria in women with South-East Asian ovalocytosis.

Malaria during pregnancy, which is characterized by the accumulation of infected erythrocytes in the placenta, often has severe consequences for the mother and newborn. We assessed the effect of the genetic trait South-East Asian ovalocytosis (SAO) on placental malaria in women from Papua New Guinea. In children, this trait confers protection against cerebral malaria, but not against mild malaria disease, malaria parasitemia, or severe malaria anemia. Using a case-control approach, we found that SAO women suffer from placental malaria, and SAO-infected erythrocytes can sequester in the placenta, but heavy placental infections tended to be less common in SAO than in control pregnant women. Reduced prevalence and severity of placental infection associated with SAO were observed only for primigravid women, who are the group at highest risk of suffering from severe manifestations of placental malaria. Furthermore, we found that the prevalence of the SAO trait was lower among pregnant women than among non-pregnant controls.