Plasmodium vivax Malaria during Pregnancy, Bolivia

In Latin America, where malaria transmission is low and mostly unstable, Plasmodium vivax is the most prevalent malaria parasite species. Although ≈3 million pregnant women are exposed to malaria in Latin America each year, the actual number of malaria infections during pregnancy is considerably lower (1). Pregnancy-associated malaria is poorly characterized in such areas of low or unstable transmission, as in most areas in which of P. vivax is predominant (2), but malaria can be severe in all parity groups because most women of childbearing age have low levels of prepregnancy and pregnancy-specific protective immunity to malaria (3). One of the first studies that demonstrated parasitization of the placenta by P. falciparum was conducted in Latin America (4), and reported serious adverse outcomes, such as miscarriages late in pregnancy or stillbirths. No other study related to pregnancy-associated malaria was conducted in Latin America for ≈80 years until a cohort study investigating P. vivax infection during pregnancy in Honduras (5) and a case-series report of 143 pregnant women infected with P. falciparum in French Guiana (6) were reported. Both studies outlined serious adverse outcomes (anemia, preterm delivery, hypotrophy, and stillbirth) associated with malaria by parasite species during pregnancy. More recent studies in the Amazon regions of Brazil and Peru reported increased incidence rates of infection with P. falciparum, but not P. vivax, in pregnant women (7,8). Outside Latin America, a few studies reported the effect of pregnancy-associated malaria in unstable malaria settings in Africa and Asia (9–12), and described increased risks for low birthweight and for maternal anemia as consequences of P. vivax infection during pregnancy (13,14). Using a hospital-based survey of women giving birth and an antenatal survey, we assessed the prevalence rates of Plasmodium infection in pregnant women in 2 malaria-endemic areas of Bolivia. We also evaluated the consequences of malaria infection during pregnancy on the health of mothers and newborns.