Malaria in pregnancy: linking immunity and pathogenesis to prevention

Pregnant women are susceptible to malaria during pregnancy. Plasmodium falciparum, which sequesters in the placenta, causes the greatest disease, contributing significantly to maternal and infant mortality. Parasitized cells in the placenta express unique variant surface antigens (VSA), predominantly the VAR2CSA protein, and lack of immunity to these pregnancy-specific variant surface antigens explains some of the pregnancy-associated malaria susceptibility. Changes in acquired cellular immunity during pregnancy also appear important. Placental inflammatory responses, particularly monocyte infiltrates, predispose to fetal growth restriction and maternal anemia. Preventing malaria in pregnancy relies on insecticide treated bed nets, intermittent preventive treatment with antimalarials such as sulphadoxine-pyrimethamine, and potentially relies on the development of effective vaccines. The optimal deployment of each may depend heavily on the relationship between the timing of placental malaria infection and its deleterious consequences. Improved understanding of the relationship between pathogenesis, immunity, and pregnancy outcome will allow better targeting of our interventions to prevent the consequences of malaria in pregnancy.