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Studies of malaria immunity in Pongonon, Mali

Location: Mali (ML).

Mosquito

Partner study description

Researchers at the Malaria Research and Training Centre, University of Bamako contributed samples from individuals in the Pongonon village in the rural Dogon region of Mali. In this region, malaria is primarily transmitted during the rainy season (June to October).

The 463 samples contributed come from two studies. The first was a prospective chloroquine efficacy study, spanning the transmission seasons of 2006-2008, where 293 uncomplicated symptomatic cases that presented at a clinic were treated with chloroquine and their infection was monitored for 28 days. The second was a cross sectional study in the rainy season of 2006-2007. In this study, 170 infected but asymptomatic individuals were identified and followed for 28 days as in the first study, but without drug treatment. Uniquely in the Consortial Project (CP2) context, all parasites were subsequently tested by polymerase chain reaction (PCR) for mutation in PfCRT. This resulted in a nested case-control study of patients that could or could not clear chloroquine resistant parasites.

Study population

The study population is almost exclusively of Dogon ethnic background. Since most malaria patients are children (0-15), this group makes up most of the study population. Of the recruited children, two fifths were under 5 years old.

Morbidity and infection density

Infection with P. falciparum parasites was determined by inspection of blood smears on slides. Asexual (blood stage) and sexual (gametocyte) forms of the parasites were counted and parasite density calculated per microlitre of blood. Infection levels were followed first daily (for three days), then weekly for the four weeks of the follow-up.

Clinical information

Clinical information, namely temperature and haemoglobin level, were recorded at several time-points for all individuals in this survey.

Study summary

One prospective and one cross-sectional survey with follow-up

448 samples

Age range: 1-61
< 5 years: 170 (38%)
5-15 years: 261 (58%)
> 15 years: 17 (4%)

Female: 192 (43%)

All individuals infected

Publications