Heamoglobin S protects against symptomless Plasmodium falciparum patent parasitaemia in two populations from Burkina Faso

HbS protects against clinical Plasmodium falciparum malaria and is associated with lower parasite densities in symptomatic subjects. Conclusive evidence of a protective role of HbS against symptomless P. falciparum infection has not been obtained so far. Here we show, in a large-scale epidemiological survey involving 2200 subjects studied during five cross-sectional surveys across two consecutive years in Burkina Faso, West Africa, that HbS is associated with a 70% reduction of harbouring a P. falciparum infection (OR=0.26 [0.11-0.60], P=0.002). This observation outlines a scenario made of consistent experimental and epidemiological observations. The abnormal display of parasite adhesive molecules on the surface of the HbS and HbC infected erythrocytes, disrupting the pathogenic process of sequestration, might displace the parasite from the deep to the peripheral circulation hence promoting its elimination at the spleen level.