Association of the sickle cell trait and the ABO blood group with clinical severity of malaria in southwest Nigeria

• Published in: Acta tropica Vol. 123; no. 2; pp. 72 - 77
• Main Authors: Amodu, O.K., Olaniyan, S.A., Adeyemo, A.A., Troye-Blomberg, M., Olumese, P.E., Omotade, O.O.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01-08-2012; Elsevier
• Subjects: ABO; ABO Blood-Group System - genetics; agglutination; anemia; Anemia - epidemiology; Anemia - genetics; Anemia - parasitology; Anemia - physiopathology; Biological and medical sciences; blood groups; blood serum; Child; Child, Preschool; childhood; children; electrophoresis; erythrocytes; Female; Gene Frequency; General aspects; Genetic Predisposition to Disease; HbS; hematocrit; hemoglobin; heterozygosity; Human protozoal diseases; Humans; indigenous species; Infant; Infectious diseases; Malaria; Malaria, Cerebral - epidemiology; Malaria, Cerebral - genetics; Malaria, Cerebral - parasitology; Malaria, Cerebral - physiopathology; Malaria, Falciparum - epidemiology; Malaria, Falciparum - genetics; Malaria, Falciparum - parasitology; Malaria, Falciparum - physiopathology; Male; males; Medical sciences; Nigeria - epidemiology; parasites; Parasitic diseases; Plasmodium falciparum; Plasmodium falciparum - pathogenicity; protective effect; Protozoal diseases; regression analysis; risk; risk reduction; Severity; Severity of Illness Index; Sickle Cell Trait - genetics; Nigeria; Africa; HbS; Plasmodium falciparum; Severity; Malaria; ABO; Protozoa; Apicomplexa; Protozoal disease; Parasitosis; Infection; Blood group; Sickle cell trait; Tropical medicine
• ISSN: 0001-706X; 1873-6254; 1873-6254
• DOI: 10.1016/j.actatropica.2012.03.013

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► We evaluate the role of HbS and ABO blood groups in malaria severity. ► The HbAS exhibits a major protective effect against severe malaria. ► The B blood group is associated with an increased risk of severe malaria. ► The HbS and ABO groups modulate the risk of severe malaria in Nigerian children.
In regions of high Plasmodium falciparum malaria endemicity, certain erythrocyte polymorphisms confer resistance to severe disease. In this study, we evaluate the role of the sickle cell trait (HbS) and ABO blood groups in the clinical manifestations of childhood malaria in Southwest Nigeria. The subjects comprised 3100 children (53% males, median age 39 months), including 1400 children with uncomplicated malaria, 1000 children with asymptomatic malaria and 700 with severe malaria. Haemoglobin (Hb) types were determined using electrophoresis and serum agglutination techniques were used to determine ABO blood groups.
Blood group O was the commonest ABO blood group (47.7%) in the study population, the others were A (22.5%), B (25.2%) and AB (4.6%). The frequencies of the HbAS and HbAC were 14.4% and 5.8%, respectively. In regression models adjusting for age, gender, parasite density and blood group, HbAS was associated with a reduced risk of severe malaria OR=0.46 (CI95%: 0.273–0.773). Among severe malaria subjects, HbAS was associated with significantly lower parasite densities. The protective effect of blood group O was demonstrated with a decreased risk of severe malaria OR=0.743 (CI95%: 0.566–0.976) after adjusting for age, gender and parasite density and Hb genotype. Blood group B was associated with increased risk of severe malaria OR=1.638 (CI95%: 1.128–2.380) after adjusting for age, gender, packed cell volume, parasite density and Hb genotype.
We have confirmed from this large study of Nigerian children the major protective effective of the sickle cell heterozygous state against both cerebral malaria and severe malarial anaemia. We also show that the B blood group is associated with an increased risk of severe malaria. In conclusion, the sickle cell haemoglobin type and ABO groups modulate the risk of severe malaria in Nigerian children.