Fc gamma receptor IIa-H131R polymorphism and malaria susceptibility in sympatric ethnic groups, Fulani and Dogon of Mali.

It has been previously shown that there are some interethnic differences in susceptibility to malaria between two sympatric ethnic groups of Mali, the Fulani and the Dogon. The lower susceptibility to Plasmodium falciparum malaria seen in the Fulani has not been fully explained by genetic polymorphisms previously known to be associated with malaria resistance, including haemoglobin S (HbS), haemoglobin C (HbC), alpha-thalassaemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Given the observed differences in the distribution of FcγRIIa allotypes among different ethnic groups and with malaria susceptibility that have been reported, we analysed the rs1801274-R131H polymorphism in the FcγRIIa gene in a study of Dogon and Fulani in Mali (n = 939). We confirm that the Fulani have less parasite densities, less parasite prevalence, more spleen enlargement and higher levels of total IgG antibodies (anti-CSP, anti-AMA1, anti-MSP1 and anti-MSP2) and more total IgE (P < 0.05) compared with the Dogon ethnic group. Furthermore, the Fulani exhibit higher frequencies of the blood group O (56.5%) compared with the Dogon (43.5%) (P < 0.001). With regard to the FcγRIIa polymorphism and allele frequency, the Fulani group have a higher frequency of the H allele (Fulani 0.474, Dogon 0.341, P < 0.0001), which was associated with greater total IgE production (P = 0.004). Our findings show that the FcγRIIa polymorphism might have an implication in the relative protection seen in the Fulani tribe, with confirmatory studies required in other malaria endemic settings.

[Place of malaria among febrile illnesses in two ethnic tribes living in sympatry in Mali from 1998 to 2008]. / Place du paludisme dans les syndromes fébriles dans deux groupes ethniques vivant en sympatrie au Mali de 1998 à 2008.

In Africa, malaria is responsible for 25-40% of all outpatient visits and 20-50% of all hospitalizations. In malaria-endemic areas, individuals do not behave the same toward the outcome of clinical malaria. The aim of this study is to determine the prevalence of malaria in the locality among the different ethnic groups, evaluate the place of malaria among febrile illnesses, and assess the relationship between fever and parasite density of Plasmodium falciparum. Studies on susceptibility to malaria between the Fulani and Dogon groups in Mali were conducted in Mantéourou and the surrounding villages from 1998 to 2008. We carried out six cross-sectional studies during the malaria transmission and longitudinal surveys (July to December depending on the year) during the 10-year duration. In longitudinal studies, clinical data on malaria and other diseases frequently observed in the population were recorded. It appears from this work that malaria is the leading cause of febrile syndromes. We observed a significant reduction in malaria morbidity in the study population from 1998 to 2008. The pyrogenic threshold of parasitaemia was 1,000 parasites/mm(3) of blood in the Dogon and 5,000 parasites/mm(3) of blood in the Fulani.We have also found that high parasitical densities were not always associated with fever. Malaria morbidity was higher among the Dogon than in Fulani. The immunogenetic factors might account for this difference in susceptibility to malaria between Fulani and Dogon in the area under study. With regard to this study, it is important to take into account the ethnic origin of subjects when interpreting data of clinical and malarial vaccine trials.

[Relationship between malaria and anemia in two ethnic groups living in sympatry in Mali]. / Relation entre l'anémie et le paludisme dans deux groupes ethniques vivant en sympatrie au Mali.

Studies performed in Burkina Faso and Mali showed differences in susceptibility to malaria between the Fulani and other sympatric ethnic groups, the Mossi and Dogon. We carried out a longitudinal survey and three cross-sectional studies from 2003 to 2005 in order to assess the prevalence of anemia in Dogon and Fulani. The distribution of the study population by sex was comparable between the two ethnic groups (p = ns). The Fulani are mainly cattle breeders and the Dogons, farmers. They were exposed to similar entomological inoculation rates, and studies on "knowledge, attitude, and practices" showed no difference between the two ethnic groups. The cross-sectional studies were performed during the intense malaria transmission season (in September 2003 and 2005) and during the dry season (in March 2004). Longitudinal clinical follow-up studies were performed from August to December 2005 using the WHO 28 days in vivo test, after administration of a curative dose of antimalarial drugs to patients with mild malaria. During the cross-sectional studies, both Fulani men and women had significantly lower hemoglobin levels than their Dogon counterparts; this difference was most evident in the women (in 2005: 9.4 g/dl in Fulani vs 10.7 g/dl in Dogon, p = 0.0002). Clinical longitudinal follow-up data showed that Fulani children aged 10-14 years have lower hemoglobin levels than Dogon children. At day 0, the mean of hemoglobin level was 9.6 g/dl in Dogon children vs. 8.7 g/dl in Fulani children (p = 0.01). At day 28, after malaria treatment, we also observed a significant difference in hemoglobin levels in children (10.6 g/dl in Dogon vs 9.3 g/dl in Fulani, p < 0.001). A stronger association between anemia and spleen enlargement was found in the Fulani (53.2% with spleen enlargement) than in the Dogon (32.9%) [p = 0.005]. The Fulani suffer more from anemia than the Dogon, despite their lower susceptibility to malaria. The difference in anemia between Dogon and Fulani must be further investigated to determine possible factors involved in malaria susceptibility.

[Frequency of glucose-6-phosphate dehydrogenase deficiency (A-376/202) in three Malian ethnic groups]. / Fréquence du déficit en glucose-6-phosphate déshydrogénase (A-376/202) dans trois groupes ethniques vivant en zone d'endémie palustre au Mali.

Erythrocyte G6PD deficiency is the most common worldwide enzymopathy. The aim of this study was to determine erythrocyte G6PD deficiency in 3 ethnic groups of Mali and to investigate whether erythrocyte G6PD deficiency was associated to the observed protection against malaria seen in Fulani ethnic group. The study was conducted in two different areas of Mali: in the Sahel region of Mopti where Fulani and Dogon live as sympatric ethnic groups and in the Sudanese savannah area where lives mostly the Malinke ethnic group. The study was conducted in 2007 in Koro and in 2008 in Naguilabougou. It included a total 90 Dogon, 42 Fulani and 80 Malinke ethnic groups. Malaria was diagnosed using microscopic examination after Giemsa-staining of thick and thin blood smear. G6PD deficiency (A-(376/202)) samples were identified using RFLP (Restriction Fragment Length Polymorphism) assay and analysis of PCR-amplified DNA amplicon. G6PD deficiency (A-(376/202)) rate was 11.1%, 2.4%, and 13.3% in Dogon, Fulani, and Malinke ethnic group respectively. Heterozygous state for G6PD (A-(376/202)) was found in 7.8% in Dogon; 2.4% in Fulani and 9.3% in Malinke ethnic groups while hemizygous state was found at the frequency of 2.2% in Dogon and 4% in Malinke. No homozygous state was found in our study population.We conclude that G6PD deficiency is not differing significantly between the three ethnic groups, Fulani, Dogon and Malinke.