Studies of Malaria Immunity in Burkina Faso

For this CP2 study the Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Burkina Faso, and the University of Rome La Sapienza, Italy, contributed samples from individuals in four rural villages of shrubby savannah areas to the east and north-east of Ouagadougou (circled on map). In this area malaria is endemic and occurs mainly during the rainy season from June to October, with people suffering in the order of 100-300 bites by infected mosquitoes each year.

The entire population of these villages participated in the study, which was designed with extensive consultation of their communities. The study consisted of five cross-sectional surveys and two longitudinal studies during two years (2007/8). The longitudinal studies (children only, around 660 per survey) cover the rainy seasons of the two years. Each was preceded and followed by cross sectional surveys, with an additional cross-sectional survey covering the intermittent dry season.

Description of the Study Population

The study population consists almost entirely of members of the Fulani (37%), Mossi (31%) and Rimaibe (28%) communities. Mossi and Fulani are mutually exclusive in the villages, and the Rimaibe are present in one Fulani and one Mossi site. About 60% of all individuals who contributed samples were children, of which half were under the age of 5 at the first survey.

Morbidity and Infection Density

Infection with malaria parasites (Plasmodium falciparum) was determined during the surveys by inspection of blood smears on thin slides. Asexual (blood stage) and sexual (gametocyte) forms of the parasites were counted on thick slides and parasite density calculated per microlitre of blood.

Clinical Information

Clinical parameters, namely temperature and haemoglobin level, were recorded for all individuals during each cross-sectional survey. All children under the age of 5 were then visited three times weekly during the surveillance period to record clinical signs, and children with fever or history of fever were tested for malaria parasites.

Map:

Side:

Summary

Cross-sectional surveys and longitudinal active case detection

DNA samples from 2177 individuals with 2232 matched plasma samples

Age range: 0 - 100

< 5 years: 727 (28%)

5-15 years: 791 (30%)

> 15 years: 1088 (42%)

female: 54%

50% of individuals positive during first cross-sectional survey

Background publications

Modiano D, Petrarca V et al. (1996). Different response to Plasmodium falciparum malaria in west African sympatric ethnic groups. Proc Natl Acad Sci USA 93(23): 13206-11.

Torcia MG, Santarlasci Vet al. (2008). Functional deficit of T regulatory cells in Fulani, an ethnic group with low susceptibility to Plasmodium falciparum malaria. Proc Natl Acad Sci USA 105(2):646-651.