Plasmodium falciparum malaria: association of sickle cell trait in the reduction of parasite density in symptomatic Fulani tribe living in sympatry in Mali, West Africa

Abstract

Background: Mutation of the b-chain of the globin gene due to a single base pair mutation A→T in the genome sequence has been associated with protection from severe malaria outcome. Differences in malaria susceptibility have been accorded to asymptomatic Fulani and other sympatric ethnic groups in Burkina Faso and Mali with Fulani being less parasitized, infected and more responsive to Plasmodium falciparum antigens. Methods & Materials: In this study, we have examined symptomatic individuals of different ethnicity (123 Fulani and 254 Dogon) in Mali, genotyped for haemoglobin S and also assessed their antibody levels to crude asexual blood-stage antigen. Results: We found that Fulani individuals with HbAA had a statistically significantly higher parasite density when compared with their HbAS counterparts [OR 1.9 (95% CI, 1.6-2.3, P < 0.001)]. The results also showed that parasite density in Dogon tribe were statistically higher than that of the Fulani tribe, irrespective of their haemoglobin status. We also found a significantly inverse correlation with parasite density and age of HbAS Fulani individuals (R2 = 0.549, P = 0.0018). No correlation between anti-malarial antibodies and haemoglobin AA or AS was observed. Conclusion: Sickle cell trait could be another contributing factor to the immuno-genetic differences observed in Fulani living in sympatry with other ethnic groups in West Africa.