Persistence of Plasmodium falciparum in the placenta after apparently effective quinidine/clindamycin therapy

The persistence of Plasmodium falciparum in the placenta after apparently adequate therapy with quinine has been described. We describe this phenomenon in the placenta of a 19-year-old woman with falciparum malaria, who was treated with a combination of quinidine and clindamycin. Although this therapy was effective and diminished her peripheral blood parasitemia from 3% at presentation to almost undetectable at the time of delivery, vast numbers of P. falciparum-infected erythrocytes were present in the maternal sinusoids of the placenta. This sequestration of infected erythrocytes produced a local parasitemia in the placenta of 70% to 80%. Additionally, rare Plasmodium-infected erythrocytes were also seen in the fetal blood of the placenta. We review malaria in pregnancy, parasitic involvement of the placenta and emphasize that Plasmodium-infected erythrocytes may persist in the placenta even after clearance of parasites from the peripheral blood.