Impact of Haemoglobin Variants AS and AC on Asymptomatic Falciparum Malaria among Adults in Iwo, Southwestern Nigeria

The aim of this study was to examine the impact of haemoglobin variants HbAS and HbAC on asymptomatic malaria compared to normal HbAA among adults living in a malaria hyperendemic area. Seemingly healthy individuals, 2,237 (≥16 years) without clinical symptoms in Iwo, Southwestern Nigeria were screened for this study after informed consent was obtained. A sample of 5 mL of blood was withdrawn from each participant for examination of malaria parasite and haemoglobin genotype. Thick and thin Giemsa stained blood smear were prepared for malaria parasite identification and quantification. Haemoglobin genotype was determined by cellulose acetate electrophoresis. The results showed that compared to HbAA, malaria infection and parasite densities were significantly lower in Hb AS (χ2 = 26.66, p < 0.001; t = 5.05, p < 0.001) and HbAC (χ2 = 6.51, p = 0.01; t = 3.70, p = 0.002). However, there was no significant difference between HbAS and HbAC individuals with respect to malaria infection and parasite density (χ2 = 0.21, p = 0.64; t = 0.22, p = 0.83). These findings suggested that among adults living in Iwo, Southwestern Nigeria, HbAS or HbAC offered better protection against asymptomatic falciparum malaria infection than HbAA while HbAS and HbAC offered similar protection.