Limited influence of haemoglobin variants on Plasmodium falciparum msp1 and msp2 alleles in symptomatic malaria

Abstract 

Haemoglobin (Hb) S, HbC, and α⁺-thalassaemia confer protection from malaria. Accordingly, these traits may influence the multiplicity of infection (MOI) of Plasmodium falciparum and the presence of distinct parasite genotypes. In 840 febrile children in northern Ghana, we typed the P. falciparum merozoite surface protein genes (msp1, msp2) and examined effects of the Hb variants on MOI and parasite diversity. HbAC, HbAS, heterozygous, and homozygous α⁺-thalassaemia occurred in 21, 5, 29 and 4% of the children, respectively. Plasmodium falciparum was detected in 95%. The haemoglobinopathies did not influence MOI, nor did the Hb type bias the distribution of the msp allelic families. However, IC type parasites were most common among patients with homozygous α⁺-thalassaemia (93%), less frequent in heterozygotes (89%), and least frequent in α-globin normal children (84%, P_(χtrend²)=0.03). The opposite was seen for Mad20 type parasites (34%, 47%, 53%, P_(χtrend²)=0.02). Only a few of the 72 individual msp alleles were selected by the haemoglobinopathies. HbC and α⁺-thalassaemia are frequent in northern Ghana. In symptomatic children, the effect of Hb variants on parasite multiplicity and diversity appears to be limited. This may reflect an actual lack of influence or indicate abrogation in symptomatic malaria.

Keywords:  Malaria, HbC, Thalassaemia, msp, MOI, Ghana