Increased efficacy of sulfadoxine-pyrimethamine in the treatment of uncomplicated falciparum malaria among children with sickle cell trait in western Kenya

The role of the sickle cell hemoglobin type as a determinant of treatment outcome with sulfadoxine-pyrimethamine was retrospectively studied in young children with uncomplicated falciparum malaria who lived in an area with intense perennial malaria transmission. Between 1993 and 1997, 2795 treatments involving 813 children were monitored. Sickle cell trait (HbAS) was present in 17.7% of the children. Two-and-a-half percent of the children experienced early clinical treatment failure by day 2-3, and 17.3% of the children were parasitemic on day 7. Treatments in HbAS children were less likely than those in HbAA children to result in persistence of parasitemia by day 3 (relative risk [RR], 0.66; 95% confidence interval [CI], 0.47-0.93; P = .02) or in parasitologic treatment failure on day 7 (RR, 0.51; 95% CI, 0.36- 0.71; P <.0001). These results suggest that the HbAS phenotype should be included among factors that determine sulfadoxine-pyrimethamine treatment outcome