Margination of red blood cells infected by Plasmodium falciparum in a microvessel.

We investigated numerically the mechanism of margination of Plasmodium falciparum malaria-infected red blood cells (Pf-IRBCs) in micro-scale blood flow. Our model illustrates that continuous hydrodynamic interaction between a Pf-IRBC in the trophozoite stage (Pf-T-IRBC) and healthy red blood cells (HRBCs) results in the margination of the Pf-T-IRBC and, thus, a longer duration of contact with endothelial cells. The Pf-T-IRBC and HRBCs first form a "train". The volume fraction of RBCs is then locally increased, to approximately 40%, and this value is maintained for a long period of time due to the formation of a long train in high-hematocrit conditions. Even in low-hematocrit conditions, the local volume fraction is instantaneously elevated to 40% and the Pf-T-IRBC can migrate to the wall. However, the short train formed in low-hematocrit conditions does not provide continuous interaction, and the Pf-T-IRBC moves back to the center of the channel.