A cohort of 250 Ghanaian schoolchildren aged 5-15 years was followed clinically and parasitologically for 4 months in 1997/98 in order to study the effect of asymptomatic Plasmodium falciparum infections on haematological indices and bone-marrow responses. Of the 250 children 65 met the predefined study criteria. Thus, 14 children were parasite-free throughout (group 1), 44 had P. falciparum in all blood samples collected but no symptoms of malaria (group 2), and 7 had 1 malaria attack during the study period (group 3). At the end of the study the mean haemoglobin (Hb) level in group 1 was 123 g/L, significantly higher than the value of 114 g/L in groups 2 and 3 (P < 0.02, adjusted for age and splenomegaly). The low Hb in group 2 was associated with subnormal plasma iron. Low Hb was associated with elevated erythropoietin (EPO) levels, and there was a positive correlation between EPO and reticulocyte counts. However, the reticulocyte response to EPO was more pronounced in uninfected than in infected children, suggesting a partial interference with erythropoiesis in asymptomatic infections. Children with asymptomatic infections had significantly higher plasma levels of tumour necrosis factor than uninfected children (geometric means 50 ng/L and 27 ng/L, respectively, P < 0.001) and this cytokine may contribute to bone-marrow suppression and disturbed iron metabolism. We suggest that asymptomatic malaria leads to a homeostatic imbalance in which erythrocyte loss due to parasite replication is only partially compensated for by increased erythropoiesis. The consequences of the reduced Hb levels on the development and cognitive abilities of children with asymptomatic infections, and the risk of precipitation of iron deficiency, deserve further study and should be considered in malaria control programmes that aim at reducing morbidity rather than transmission.
BackgroundABO blood group antigens are formed by terminal glycosylation of glycoproteins and glycolipid chains present on cell surfaces. Glycosylation modulates all kinds of cell-to-cell interactions and this may be relevant in malaria pathophysiology, in which adhesion has been increasingly implicated in disease severity. This study was done to determine the association between ABO phenotypes and the severity of P. falciparum malaria in children.MethodsOne hundred and twenty one children were assessed at the Department of Child Health, KBTH from May to August 2008. ABO blood groups were determined by agglutination. The haemoglobin measurement was done with the haematology analyzer, Sysmex KX-21N. Malaria parasites were enumerated and the presence of malaria pigment noted. Identification of P. falciparum was done. Statistical tests used were odds ratio and chi square at a significance level of p<0.05.Results24.3% of the 121 children had severe falciparum malaria, and their mean haemoglobin was 4.49 g/dl (SD ±1.69). No significant association was found between the ABO phenotypes and malaria infection (p>0.05). Blood group A was associated with more severe malaria as compared to the blood group O individuals (Odds ratio=0.79, p>0.05); blood group AB (Odds ratio=0.14, p>0.05) and also there was a significant difference in severity of malaria between blood group O and blood group B (Odds ratio=1.28, p>0.05).ConclusionNon-O blood group children are more prone to severe malaria caused by P. falciparum malaria than the group O, despite the lack of significant association between ABO blood groups and falciparum malaria.
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