For this Consortial Project 2 study the Institut Pasteur de Dakar contributed samples from individuals in two communities, Dielmo and Ndiop, about 300km south of Dakar (circled on map). Of special interest for CP2 is that while in Dielmo, malaria is transmitted throughout the year (holoendemic), in Ndiop, transmission is seasonal, namely primarily during the rainy season from June to October (mesoendemic). Furthermore, since malaria-related studies have been conducted in these villages for over 20 years, a wealth of historical and background data is available.

The 541 samples (259 from Ndiop) contributed to CP2 were taken in January 2007 as part of a long-term longitudinal survey from July 2006 to June 2007. During this survey, the participating adults and children were visited daily to record general health and detect any disease episodes.

Description of Study Population

In Dielmo, there are 10 ethnic groups, by far the largest being Serere Niominka (60%). In Ndiop around 70% of the population is Wolof and four other ethnic groups are present. Fulani are found in both villages - around 5% in Dielmo and almost 20% in Ndiop.

About half of the study population are adults (>15 years) and children account for 15% of the participating individuals in both communities.

Morbidity and Infection Density

Infection with malaria parasites (Plasmodium falciparum, malariae and ovale) was determined by inspection of blood smears on slides for both asexual (blood stage) and sexual (gametocyte) forms. Around 40% of all participating individuals (33% in Dielmo, 47% in Ndiop) suffered at least one malaria episode during the surveillance period. Of these, the majority had exactly one episode, but some individuals suffered up to 7.

Clinical Information

For any individual with a symptomatic malaria attack, the maximum temperature during any one attack and the mean temperature over all attacks were recorded.