Genetic diversity of Plasmodium falciparum among school-aged children from the Man region, western Côte d’Ivoire

Abstract

BackgroundThe genetic diversity of Plasmodium falciparum allows the molecular discrimination of otherwise microscopically identical parasites and the identification of individual clones in multiple infections. The study reported here investigated the P. falciparum multiplicity of infection (MOI) and genetic diversity among school-aged children in the Man region, western Côte d’Ivoire.MethodsBlood samples from 292 children aged seven to 15 years were collected in four nearby villages located at altitudes ranging from 340 to 883 m above sea level. Giemsa-stained thick and thin blood films were prepared and examined under a microscope for P. falciparum prevalence and parasitaemia. MOI and genetic diversity of the parasite populations were investigated using msp2 typing by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).ResultsPlasmodium falciparum prevalence and parasitaemia were both found to be significantly lower in the highest altitude village. Genotyping of the isolates revealed 25 potentially new msp2 alleles. MOI varied significantly across villages but did not correlate with altitude nor children’s age, and only to a limited extent with parasitaemia. An analysis of molecular variance (AMOVA) indicated that a small, but close to statistical significance (p = 0.07), fraction of variance occurs specifically between villages of low and high altitudes.ConclusionsHigher altitude was associated with lower prevalence of P. falciparum but not with reduced MOI, suggesting that, in this setting, MOI is not a good proxy for transmission. The evidence for partially parted parasite populations suggests the existence of local geographical barriers that should be taken into account when deploying anti-malarial interventions.

Genetic polymorphism of Merozoite Surface Protein-2 (MSP-2) in Plasmodium falciparum isolates from Pawe District, North West Ethiopia

“…The MOI reported in this study was high compared to those reported from a moderate transmission region in Kolla-Shele Southwest Ethiopia [16], but consistentwith findings from Cote d’Ivoire [30]. Thisisinagreement withprevious observations of an increased MOIwith increase ingendemicity [31].…”

Confirmation of the absence of local transmission and geographic assignment of imported falciparum malaria cases to China using microsatellite panel

“…Due to the physical proximity of the newly designed markers with the existing loci, we expected strong pairwise linkage disequilibrium between flanking microsatellites, however the pairwise LD was very low even among loci within 1000 bp on the same chromosome, suggesting very high rate of recombination in P. falciparum parasites in sub-Saharan Africa as described previously [36,37]. This observation is further evidenced by high genetic diversity in imported infection, similar to the level reported from local parasite populations [34,38,39] and the lack of detectable geographic clusters.…”

Acquisition, maintenance and adaptation of invasion inhibitory antibodies against Plasmodium falciparum invasion ligands involved in immune evasion

“…Importantly, the scenario observed in which infection intensity (mean parasitaemia) was slightly higher in the rainy season and lower in the dry season, but with a common occurrence of parasites detectable in the blood throughout the seasons, may suggest that the upsurge in malaria cases or parasite intensity usually recorded in the rainy seasons is due to transmission of antigenically distinct malaria parasites between individuals. Indeed, a recent study in a west African country has shown that the number of clonal infections per individual could range from 1 to 8, depending on other characteristics of an area [ 45 ]. The sustained parasite prevalence through the seasons shown here is also in agreement with previous results obtained from our study site that showed 42% and 48% prevalence for the dry and rainy seasons, respectively [ 46 ].…”