title: A model of parity-dependent immunity to placental malaria.
abstract: Plasmodium falciparum placental infection during pregnancy is harmful for both mother and child. Protection from placental infection is parity-dependent, that is, acquired over consecutive pregnancies. However, the infection status of the placenta can only be assessed at delivery. Here, to better understand the mechanism underlying this parity-dependence, we fitted a model linking malaria dynamics within the general population to observed placental histology. Our results suggest that immunity resulting in less prolonged infection is a greater determinant of the parity-specific patterns than immunity that prevents placental sequestration. Our results also suggest the time when maternal blood first flows into the placenta is a high-risk period. Therefore, preventative strategies implementable before or early in pregnancy, such as insecticide-treated net usage in women of child-bearing age or any future vaccine, could substantially reduce the number of women who experience placental infection.
authors.affiliation: MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK. patrick.walker@imperial.ac.uk
authors.forename: Patrick G T
authors.initials: PG
authors.lastname: Walker
authors.forename: Jamie T
authors.initials: JT
authors.lastname: Griffin
authors.forename: Matt
authors.initials: M
authors.lastname: Cairns
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rogerson
authors.forename: Anna M
authors.initials: AM
authors.lastname: van Eijk
authors.forename: Feiko
authors.initials: F
authors.lastname: ter Kuile
authors.forename: Azra C
authors.initials: AC
authors.lastname: Ghani
mesh_terms: D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000276:immunology*; D010922:Placenta Diseases / Q000276:immunology*; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000276:immunology*