Plasmodium falciparum: effect of infected erythrocytes on clotting time of plasma.

Procoagulant activity of erythrocytes infected with Plasmodium falciparum was determined by measuring the effect of infected erythrocytes on the clotting time of platelet-poor human plasma in the presence of Russell's viper venom. We found that erythrocytes infected with P. falciparum enhanced clotting. In the presence of the infected erythrocytes, clotting times were significantly shortened compared to clotting times in the presence of uninfected erythrocytes. Procoagulant activity of infected erythrocytes, especially at high parasitemia, may be a factor in the pathogenesis of disease in falciparum malaria.