Veenemans, Jacobien, Andang'o, Pauline E. A., Mbugi, Erasto V., Kraaijenhagen, Rob J., Mwaniki, David L., Mockenhaupt, Frank P., Roewer, Susanne, Olomi, Raimos M., Shao, John F., van der Meer, Jos W. M., Savelkoul, Huub F. J., and Verhoef, Hans
Background. In hospital-based studies,α+-thalassemia has been found to protect against severe, life-threatening falciparum malaria. α+-Thalassemia does not seem to prevent infection or high parasite densities but rather limits progression to severe disease—in particular, severe malarial anemia. We assessed to what extent α+-thalassemia influences the association between mild, asymptomatic Plasmodium falciparum infection and hemoglobin concentration. Methods. The study was based on 2 community-based surveys conducted among afebrile children (0.5—8 years old; n =801) in Kenya and Tanzania. Results. Among children without inflammation (whole-blood C-reactive protein concentration ⩽10 mg/L), P. falciparum infection was associated with only small reductions in hemoglobin concentration, and effects were similar across α-globin genotypes. By contrast, the reduction in hemoglobin concentration associated with P. falciparum infection accompanied by inflammation was larger and strongly depended on genotype (normal, —21.8 g/L; heterozygous, —16.7 g/L; and homozygous,—.6 g/L). Relative to children with a normal genotype, this difference in effect was 5.1 g/L (95% confidence interval [CI], —1.0 to 11.1 g/L) for heterozygotes and 17.2 g/L (95% CI, 8.3 to 26.2 g/L) for homozygotes (estimates are adjusted for study site, age, height-for-age z score, and iron deficiency). Conclusions. α+-Thalassemia limits the decline in hemoglobin concentration that is associated with afebrile infections, particularly those that are accompanied by inflammation. [ABSTRACT FROM AUTHOR]