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

Mara SE, Silué KD, Raso G, N'guetta SP, N'goran EK, Tanner M, Utzinger J, Ding XC - Malar. J. (2013)

Bottom Line: Plasmodium falciparum prevalence and parasitaemia were both found to be significantly lower in the highest altitude village.MOI varied significantly across villages but did not correlate with altitude nor children's age, and only to a limited extent with parasitaemia.Higher 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Côte d'Ivoire. xavier.ding@gmail.com.

ABSTRACT

Background: The 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.

Methods: Blood 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).

Results: Plasmodium 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.

Conclusions: Higher 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.

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Study sites location. Four villages located in the Man region, western Côte d’Ivoire, were selected for this study. Bogouiné II and Bloleu are in a plain at relatively low altitude (340 and 346 m above sea level, respectively). Mélapleu and Sandougou-soba are in a mountainous area at relatively high altitude (529 and 883 m, respectively). Maps have been generated using GPS Visualizer [24].
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Figure 1: Study sites location. Four villages located in the Man region, western Côte d’Ivoire, were selected for this study. Bogouiné II and Bloleu are in a plain at relatively low altitude (340 and 346 m above sea level, respectively). Mélapleu and Sandougou-soba are in a mountainous area at relatively high altitude (529 and 883 m, respectively). Maps have been generated using GPS Visualizer [24].

Mentions: A large study of the demographic, environmental and socioeconomic risk factors associated with malaria, schistosomiasis and soil-transmitted helminthiasis was previously conducted in 57 villages of the mountainous region of Man in western Côte d’Ivoire [18-21]. The local topography is an extension of the Fouta Djallon highland area and is characterized by rounded mountains in the north, ranging in altitudes from 200 to 1,300 m above sea level, and an abrupt transition to plains in the south. The area is hyperendemic for P. falciparum infection and polyparasitism (concurrent infection with different species of helminths, intestinal protozoa and Plasmodium) is very common [22]. In the work presented here, the MOI with P. falciparum is further explored. Additionally, the genetic diversity of the local P. falciparum populations is assessed for a subset of the previously collected samples. Specifically, four villages located in close proximity to each other but at various altitudes have been selected (Figure 1). Emphasis is placed on a small-scale comparison of P. falciparum msp2 allelic diversity in close but geographically contrasted areas of western Côte d’Ivoire. The importance of the findings in the context of the current malaria elimination and eradication agenda [23] is discussed.


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

Mara SE, Silué KD, Raso G, N'guetta SP, N'goran EK, Tanner M, Utzinger J, Ding XC - Malar. J. (2013)

Study sites location. Four villages located in the Man region, western Côte d’Ivoire, were selected for this study. Bogouiné II and Bloleu are in a plain at relatively low altitude (340 and 346 m above sea level, respectively). Mélapleu and Sandougou-soba are in a mountainous area at relatively high altitude (529 and 883 m, respectively). Maps have been generated using GPS Visualizer [24].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842749&req=5

Figure 1: Study sites location. Four villages located in the Man region, western Côte d’Ivoire, were selected for this study. Bogouiné II and Bloleu are in a plain at relatively low altitude (340 and 346 m above sea level, respectively). Mélapleu and Sandougou-soba are in a mountainous area at relatively high altitude (529 and 883 m, respectively). Maps have been generated using GPS Visualizer [24].
Mentions: A large study of the demographic, environmental and socioeconomic risk factors associated with malaria, schistosomiasis and soil-transmitted helminthiasis was previously conducted in 57 villages of the mountainous region of Man in western Côte d’Ivoire [18-21]. The local topography is an extension of the Fouta Djallon highland area and is characterized by rounded mountains in the north, ranging in altitudes from 200 to 1,300 m above sea level, and an abrupt transition to plains in the south. The area is hyperendemic for P. falciparum infection and polyparasitism (concurrent infection with different species of helminths, intestinal protozoa and Plasmodium) is very common [22]. In the work presented here, the MOI with P. falciparum is further explored. Additionally, the genetic diversity of the local P. falciparum populations is assessed for a subset of the previously collected samples. Specifically, four villages located in close proximity to each other but at various altitudes have been selected (Figure 1). Emphasis is placed on a small-scale comparison of P. falciparum msp2 allelic diversity in close but geographically contrasted areas of western Côte d’Ivoire. The importance of the findings in the context of the current malaria elimination and eradication agenda [23] is discussed.

Bottom Line: Plasmodium falciparum prevalence and parasitaemia were both found to be significantly lower in the highest altitude village.MOI varied significantly across villages but did not correlate with altitude nor children's age, and only to a limited extent with parasitaemia.Higher 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Côte d'Ivoire. xavier.ding@gmail.com.

ABSTRACT

Background: The 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.

Methods: Blood 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).

Results: Plasmodium 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.

Conclusions: Higher 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.

Show MeSH
Related in: MedlinePlus