Effect of ABO/Rhesus blood group phenotypes on immunosurveillance to plasmodium falciparum malaria in children in Kisumu town, Kenya

Malaria is the world leading cause of deaths among the tropical infectious diseases particularly in children and pregnant women. A safe and effective vaccine would have been the easiest way to control this disease, but the development of vaccine has not been successful despite decades of research. The periodic mutation and production of parasite variants has not only posed a challenge to the vaccine production but also drug resistance. Also important is host-related factors that contribute to disease susceptibility and resistance. Although ABO Blood group phenotypes have been correlated with protection against malaria infection especially in Sir Lanka and Gabon, little study has been done in Africa and Kenya in particular. This study aimed at investigating the effect of ~01Rh blood group phenotypes on immunosurveillance to P. falciparum infection in children 1-10 years in Kisumu town. The study design adopted was simple cross sectional study, while population sampling technique used was probability proportion to size. The study was done with 78 malaria symptomatic children both males and females who presented at Nyanza Provincial General Hospital and living within Kisumu town. Children age between I10 years whose parents or guardians consented to the study were enrolled. The study population exhibited a predominance of group 0+, in the order of 0+ >A+ >B+ > AB+ and 0-. Blood group 0 was negatively correlated with malaria infection. Parasitaemia levels were significantly higher in blood group A+ and B+ than in group O+. It was further established that blood group A+ registered the highest percentage malaria severity (45.8%) while group 0+ recorded the least severity (8 .6%). Helper CD/ and cytotoxic CD8+ subsets of T-lymphocytes cells were both inversely correlated with parasitaemia levels (r = -162, P = 0.04; r = -0.348, P = 0.002) respectively. Nevertheless, no significant association was observed between parasitaemia levels and differential leukocyte counts (P = 0.05). ANOVA revealed significant difference in malaria infection between and females with males having higher infection (p = 0.04). However age was inversely correlated with parasitaemia levels (r = -0.0278, P = 0.007) with younger children having higher parasitaemia levels than the older ones. Parasitaemia levels were significantly higher in males than female children, sex was positively correlated with malaria parasite infection (r = 0.199, P = 0.040). The results of this study therefore implicate blood group 0 in protection against malaria while group A and B are likely to predispose the victims to the infection. Since blood group A correlated with malaria infection and disease severity, its advisable that blood group A individuals traveling to malaria endemic areas be given prophylaxis. T-helper and cytotoxic T-lymphocyte cell levels decrease in severe malaria cases hence malaria infected individuals have reduced immunosurveillance. Since Helper 'I'-cell (CD4+) and cytotoxic (CD8+) subsets ofTlymphocytes cells were reduced in malaria cases it is therefore imperative for the clinicians to monitor the levels of such cells in severe malaria cases and if possible immunopotentiaters be given since reduced levels of Helper T-cells and cytotoxic Tlymphocytes cells may subject the victim to prolonged healing and coinfections. Higher parasitaemia levels in males than in females living in the same malaria holoendemic areas are an indicator that males are more vulnerable to malaria infection than females.