The role of red blood cell polymorphisms in resistance and susceptibility to malaria

In regions highly endemic for Plasmodium falciparum malaria, red cell polym orphisms that confer resistance to severe disease are widespread. Sickle ce ll trait, alpha-thalassemia, glucose-6-phosphate dehydrogenase deficiency, and blood groups were determined in 100 children from Gabon with severe mal aria who were matched with 100 children with mild malaria and followed up f or evaluation of reinfections. The sickle cell trait was significantly asso ciated with mild malaria and blood group A with severe malaria. During foll ow-up, the original severe cases had significantly higher rates of reinfect ion than the original mild cases, with higher parasitemia and lower hematoc rit values. Incidence rates did not differ in the contest of erythrocyte po lymorphisms, but patients with sickle cell trait presented with markedly lo wer levels of parasitemia than those without, Thus, the severity of malaria is partly determined by the presence of blood group A and the sickle cell trait. The different presentation of reinfections in severe versus mild cas es probably reflects different susceptibility to malaria.