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London School of Hygiene & Tropical Medicine Malaria Centre

Malaria research in parasite biology

Malaria parasite population structure and adaptation on the edge of endemic distribution in Africa.

LSHTM investigators:
Craig Duffy & David Conway
External collaborators:
Hampate Ba (Recherches en Santé Publique, Mauritania); Ambroise Ahouidi (Cheikh Anta Diop University, Senegal); Dominic Kwiatkowski (Wellcome Trust Sanger Institute, UK); Manoj Duraisingh (Harvard University, USA).
Funding body:
Medical Research Council, UK.

We are investigating population genetic structure and phenotypes of P. falciparum under selection at the north western extreme of its African range in Mauritania, where endemicity persists despite limited and highly seasonal rainfall that restricts transmission.

We predict that, genetic divergence between populations of P. falciparum in different areas of Mauritania will be high due to genetic drift with small effective population sizes, and restricted gene flow among endemic foci. This is being investigated by microsatellite and whole genome sequence polymorphism analyses. We also predict that the selective landscape will be strikingly different from elsewhere, leading to measurable effects including the following:

  • Low levels of acquired immunity in the human population will reduce diversifying selection on merozoite invasion ligands so these will be less diverse and skewed towards the use of a preferred primary ligand;
  • Alleles under strong positive selection will increase to high frequencies in local populations before sporadic gene flow events allow them to spread so there will be major local differences in drug resistance.

Understanding these processes in terms of demographic and selective constraints on the parasite will guide targeting of existing control tools including antimalarial drugs and development of new tools including vaccines.