Placental Malaria: Histological Findings and Immune Cell Infiltrates in Submicroscopic Infections

Abstract Most research on placental malaria is focused on microscopic infection by Plasmodium falciparum; there are very few studies on submicroscopic infection. This study aimed to assess alterations of placental tissue associated with placental malaria, to describe the immune cell populations in the placental tissue, and to explore the relationships between the histopathological changes and cell infiltrates. A descriptive, prospective and cross-sectional study was carried out. Women were recruited at hospital obstetric facilities in three municipalities in Northwest Colombia. The histopathological analysis was performed in a total of 132 placentas including 66 placentas with submicroscopic plasmodial infection and 66 that were negatives. Immunohistochemistry was performed on a subset of 75 placentas to determine the distribution of immune cells. Based on histology, there were more immune cells in placentas with submicroscopic plasmodial infection compared with those without infection. The quantity of syncytial knots and calcifications was greater with submicroscopic plasmodial infection, but the quantity of abruption and thrombi was greater in placentas without infection. By immunohistochemistry, we observed a significant increase of CD56+ and CD68+ cells in the infected placentas. Submicroscopic plasmodial infection in the placenta causes tissue alterations and increased immune cell infiltrates. Submicroscopic plasmodial infection is very common in Colombia and can represent a serious threat to mothers and newborns.