FcγRIIa polymorphism and anti-malaria-specific IgG and IgG subclass responses in populations differing in susceptibility to malaria in Burkina Faso.

FcγRIIa is known to be polymorphic; and certain variants are associated with different susceptibilities to malaria. Studies involving the Fulani ethnic group reported an ethnic difference in FcγRIIa-R131H genotype frequencies between the Fulani and other sympatric groups. No previous studies have addressed these questions in Burkina Faso. This study aimed to assess the influence of FcγRIIa-R131H polymorphism on anti-falciparum malaria IgG and IgG subclass responses in the Fulani and the Mossi ethnic groups living in Burkina Faso. Healthy adults more than 20 years old belonging to the Mossi or the Fulani ethnic groups were enrolled for the assessment of selected parasitological, immunological and genetic variables in relation to their susceptibility to malaria. The prevalence of the Plasmodium falciparum infection frequency was relatively low in the Fulani ethnic group compared to the Mossi ethnic group. For all tested antigens, the Fulani had higher antibody levels than the Mossi group. In both ethnic groups, a similar distribution of FcγRIIa R131H polymorphism was found. Individuals with the R allele of FcγRIIa had higher antibody levels than those with the H allele. This study confirmed that malaria infection affected less the Fulani group than the Mossi group. FcγRIIa-R131H allele distribution is similar in both ethnic groups, and higher antibody levels are associated with the FcγRIIa R allele compared to the H allele.

[Comparative impact of three malaria preventive regimens during pregnancy on maternal anemia due to malaria in Burkina Faso]. / Impact comparatif de trois schémas de prévention du paludisme pendant la grossesse sur l'anémie maternelle, associée à l'infection palustre au Burkina Faso.

OBJECTIVES: The main objective of this study was to compare the efficacy of three regimens of malaria prevention during pregnancy for the reduction of anemia between the first and third antenatal consultations. The first treatment arm was the classical weekly chemoprophylaxis with chloroquine; the other two were the intermittent preventive treatment using either three doses of chloroquine or sulfadoxine-pyrimethamine. DESIGN: We conducted an open, randomized, three-arm study in a rural district of Burkina Faso. A cohort was constituted by 648 pregnant women of any parity. RESULTS: The hemoglobin gain was more significant with the intermittent preventive treatment using sulfadoxine-pyrimethamine compared to the other treatment arms. The hemoglobin increased from 10.3g/dl (at the first antenatal consultation) to 11.4 g/dl (at the third antenatal consultation). In the three arms of treatment, the chemoprophylaxis reduced the prevalence of moderate anemia and severe anemia. The reduction of moderate anemia was more substantial in the sulfadoxine-pyrimethamine arm (65.6 to 36.7%) at second antenatal consultation (p=0.069) and third antenatal consultation (p=0.014). Conversely, in the two chloroquine arms, there was no significant reduction either at second antenatal consultation (p=0.72) or third antenatal consultation (p=0.55). The prevalence of peripheral parasitemia decreased in all treatment groups. However, it was significantly higher in the sulfadoxine-pyrimethamine group (44.3%). CONCLUSIONS: Intermittent preventive treatment with three doses of sulfadoxine-pyrimethamine is a more effective strategy to prevent maternal anemia during pregnancy in Burkina Faso.

Morbidite du paludisme en zone hyper-endemique du Burkina Faso : etude de l'indice plasmodique et de l'incidence des formes cliniques

Dans le but de mesurer la morbidite du paludisme en zone hyper-endemique; l'indice plasmodique et l'incidence du paludisme ont ete mesurees pendant la saison de haute transmission 2002 (septembre en novembre) sur une cohorte de 403 sujets residant a Tensobentenga. Situe a 50 km a l'Est de Ouagadougou; le taux d'inoculation entomo- logique dans ce village etait d'environ 1;7 piqures infectees par personne et par nuit.. La cohorte composee de 228 enfants de 0-10 ans et 175 adultes a fait l'objet d'un suivi actif quotidien. Un passage transversal a ete effectue en octobre 02. Durant la periode de suivi; 636 episodes de fievre ont ete declares soit en moyenne 1;6 episodes par personne (2;4 chez les enfants et 0;5 chez les adultes; p 0;001). 303 episodes d'acces palustre (fievre observee ou rapportee associee a une parasitemie); ont ete notes dont 26 episodes chez les 18 a 40 ans et 277 chez les moins de 10 ans. Les acces palustres etaient associes a des vomissements dans 13;2et la diarrhee dans 6. Le nombre moyen d'acces palustres chez les adultes et chez les enfants etait respectivement de 0;15 et de 1;21 (p 0;001). Le nombre d'episode decroissait selon que l'on avancait dans la saison de transmission. Le taux d'incidence du paludisme etait de 3;1 pour 1000 personnes-jours chez l'adulte et de 19;5 pour 1000 personnes jours chez l'enfant (p 0;001). Au passage transversal; l'indice plasmodique global etait de 61;2; 29;7chez les adultes et 78chez les enfants; (p 0;001). La densite parasitaire moyenne etait de 1309 parasites/ l et diminuait significativement avec l'age (p0;001). Le taux de portage des gametocytes etait 12; et diminuait avec l'age jusqu' a 30 ans (p0;001). En conclusion; les enfants sont les plus infectes par le plasmodium en zone d'endemie. Il apparait aussi clairement que la prise en charge correcte des cas constitue une autre forme de prophylaxie du paludisme en periode de haute transmission