Placental Malaria in Women With South-East Asian Ovalocytosis

Abstract

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.

Malaria in pregnancy in the Asia-Pacific region

“…In India and Papua New Guinea, P falciparum resistance to chloroquine and sulfadoxine-pyrimethamine is high. 20,29,35,36,40,41,42 Despite diff erences in transmission, this fi nding could be a result of increased clearance of parasites from the maternal and placental blood by the more eff ective artemisinin-based combination therapies. …”

“…9,31,37,60 Even asymptomatic malaria episodes could cause anaemia, 37 and women during their second or subsequent pregnancies are more anaemic than are women in their fi rst pregnancy. 37,42,48,50 Severe maternal anaemia during pregnancy increases risk of premature labour 37,41 and stillbirth, 61,62 and reduces birthweight. 37,48,58 Data from Thailand suggest that risk of P vivax malaria increases after start of haematinic supplementation (iron and folate).…”

“…Although southeast Asian ovalocytosis and α thalassaemia protect young children in Papua New Guinea against cerebral malaria, 64,65 neither genetic trait seems to change the eff ects of malaria in pregnancy. 42,59,66 The risk of thrombocytopenia is more than two times higher in pregnant women with malaria than in non-pregnant women infected with malaria, but this disorder is rarely severe (less than 10 000 platelets per μL). 60,67 Prompt antimalarial treatment can normalise platelet counts within a week.…”

“…The median reduction in birthweight in the reviewed studies was 150 g (range 1-650; fi gure 3) for P falciparum or mixed infections, 20,29,36,37,41,42,44,47,48,88,89 and 108 g (107-310) for P vivax malaria. 9,29,37 Birthweight reduction occurs mainly in fi rst pregnancies with P falciparum malaria but also in subsequent pregnancies, and even with one episode of P vivax or P falciparum malaria.…”

“…Longlasting Allen 1998 41 Benet 2006 42 Kaushik 1992 88 Nosten 1991 48 Poesproprodjo 2008 37 Singh 1999 29 Brabin 1990 Primip 89 Brabin 1990 Multip 89 Hamer 2009 Review insecticide-treated bednets are distributed in all countries, 14 but reports in the past 3 years have shown low availability or use by pregnant women. 26,34,128 Case management is available everywhere, but in reality malaria smears are obtained from pregnant women only when fever or other malarial symptoms are present and these symptoms are often not checked by health workers.…”