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A longitudinal study was undertaken in Burkina Faso among 293 children aged 6 months to 9 years in order to determine the correlation between an antibody response to several individual malarial antigens and malarial infection. It was found that the presence of a positive antibody response at the beginning of the rainy season to three long synthetic peptides corresponding toPlasmodium falciparumExp-1 101–162, MSP-3 154–249 and GLURP 801–920 but not to CSP 274–375 correlated with a statistically significant decrease in malarial infection during the ongoing transmission season. The simultaneous presence of an antibody response to more than one antigen is indicative of a lower frequency of malarial infection. This gives scientific credibility to the notion that a successful malaria vaccine should contain multiple antigens. [ABSTRACT FROM AUTHOR]

The Fulani are less clinically susceptible and more immunologically responsive to malaria than neighbouring ethnic groups. Here we report that anti-malarial antibody levels show a wide distribution amongst the Fulani themselves, raising the possibility that quantitative analysis within the Fulani may be an efficient way of screening for important genetic factors. The Th2 cytokine interleukin-4 is an obvious candidate: in Fulani, the IL4-524 T allele is at high frequency and is associated with elevated antibody levels against malaria antigens. These data highlight the possibility of combining interand intra-ethnic comparisons to characterize critical determinants of malarial immunity in a natural setting. Genes and Immunity (2001) 2, 411-414. [ABSTRACT FROM AUTHOR]

Burkina Faso has recently changed the antimalarial drug policy to artesunate/amodiaquine or artemether/lumefantrine as the first-line antimalarial drug and sulfadoxine/pyrimethamine for the intermittent preventive treatment in pregnant woman. Before the implementation of this new strategy we conducted an in vivo efficacy study with chloroquine or sulfadoxine/pyrimethamine for treatment of uncomplicated Plasmodium falciparum malaria in urban area of Burkina from September to December 2003. Chloroquine (25 mg/kg over 3 days) or sulfadoxine/pyrimethamine (25 mg/kg + 0.025 mg/kg single dose) was administered respectively to 137 and 125 children aged from 6 to 59 months old in a randomized, opened study. Follow up extended over 28 days using modified WHO protocol. After adjusting the results by PCR, treatment failures rates were 63.4% (83/131) and 13.8% (17/123) respectively for chloroquine and sulfadoxine/pyrimethamine. These results with other observations have justified the change of malaria therapy policy in Burkina Faso in 2005.

Haemoglobin C (HbC; beta6Glu --> Lys) is common in malarious areas of West Africa, especially in Burkina Faso. Conclusive evidence exists on the protective role against severe malaria of haemoglobin S (HbS; beta6Glu --> Val) heterozygosity, whereas conflicting results for the HbC trait have been reported and no epidemiological data exist on the possible role of the HbCC genotype. In vitro studies suggested that HbCC erythrocytes fail to support the growth of P. falciparum but HbC homozygotes with high P. falciparum parasitaemias have been observed. Here we show, in a large case-control study performed in Burkina Faso on 4,348 Mossi subjects, that HbC is associated with a 29% reduction in risk of clinical malaria in HbAC heterozygotes (P = 0.0008) and of 93% in HbCC homozygotes (P = 0.0011). These findings, together with the limited pathology of HbAC and HbCC compared to the severely disadvantaged HbSS and HbSC genotypes and the low betaS gene frequency in the geographic epicentre of betaC, support the hypothesis that, in the long term and in the absence of malaria control, HbC would replace HbS in central West Africa.

The age distribution and the clinical patterns of severe malaria (SM) were compared in patients from urban areas characterized by relatively low transmission, and from rural areas where the mean inoculation rates are at least twenty fold higher. The mean age of the urban and rural patients was 4.8 +/- 3.0 and 2.2 +/- 1.9 respectively (p < 0.000). The prevalence of coma was higher in the urban subsample (53.6 vs 28.9%, p << 0.000) while that of severe anemia (hemoglobin < 5 g/dl) was higher in rural patients (47.4 vs 14.8%, p < 0.000). Our data, in line with previous results obtained comparing rural areas characterized by different inoculation rates, show that the epidemiological context influences the clinical presentation of SM.

The comparison of malaria indicators among populations with different genetic backgrounds and uniformly exposed to the same parasite strains, is one of the approaches to the study of human heterogeneities in the response to the infection. The results of our comparative studies conducted in Burkina Faso, West Africa, showed consistent interethnic differences in Plasmodium falciparum infection rates, malaria morbidity, prevalence and levels of antibodies to various P. falciparum antigens, and genetic background. The differences in the immune response were not explained by the entomological observations which indicated substantially uniform exposure to infective bites. The presence in the same epidemiological context of individuals characterized by different immune reactivity to malaria represents an ideal opportunity to study the possible relationships between the baseline level of anti-malaria immunity of a population and the protective efficacy of control measures based on the reduction of transmission. In spite of similar reduction of entomological inoculation rates obtained by permethrin-impregnated curtains, ethnic- and age-dependent efficacy was observed. These studies demonstrate the existence of marked interethnic differences in the susceptibility to P. falciparum malaria, probably involving the genetic regulation of humoral immune responses. These differences should be considered in the development of anti-malaria vaccines and in the evaluation and application of malaria control strategies.

Plasmodium falciparum parasite rate, parasite density and anti-CS antibodies were assessed in 196 subjects (age > 10 yrs) belonging to three sympatric West African ethnic groups, namely Mossi, Rimaibé and Fulani, all exposed to very high seasonal malaria transmission in the same rural village near Ouagadougou, Burkina Faso. No interethnic differences were noted in the use of antimalaria measures nor in the exposure to malaria vectors. However, interethnic differences were found in each of the three malariological indices. The Fulani appeared markedly less parasitized and more responsive to the CS-antigen than the Mossi and the Rimaibé who had very similar indices, except in the case of parasite density. These findings suggest a higher resistance to malaria of the Fulani ethnic group, possibly involving human genetic factors and/or the influence of extrinsic variables (e.g., socio-cultural) among which diet differences should be considered.