The role of reduced red cell deformability in the pathogenesis of severe falciparum malaria and its restoration by blood transfusion.

As reduced red cell deformability (RCD) can contribute to derangement of the microcirculation, a central feature in the pathogenesis of severe malaria, RCD was measured with a laser diffraction technique in 232 consecutive patients with falciparum malaria on the Kenyan coast, of whom 99 had severe disease. RCD on admission (measured as elongation index [EI] at shear stress = 1.7 Pa) was reduced in proportion with severity of disease (fatal outcome: EI = 0.182 (SD = 0.048), survivors from severe disease: EI = 0.217 (SD = 0.043), uncomplicated malaria: EI = 0.249 (SD = 0.030), healthy controls: EI = 0.268 (SD = 0.022). All but 2 survivors with severe malaria and rigid erythrocytes received a blood transfusion restoring RCD. Reduced RCD may contribute to impaired microcirculatory flow and a fatal outcome in falciparum malaria. RCD can be improved by blood transfusion. Since severely reduced RCD has a strong predictive value for mortality, blood transfusion possibly improves disease outcome not only through its beneficial effect on anaemia but also on RCD.