title: Population genetics analysis during the elimination process of Plasmodium falciparum in Djibouti.
abstract: BACKGROUND
  Case management of imported malaria within the context of malaria pre-elimination is increasingly considered to be relevant because of the risk of resurgence. The assessment of malaria importation would provide key data i) to select countries with propitious conditions for pre-elimination phase and ii) to predict its feasibility. Recently, a sero-prevalence study in Djibouti indicated low malaria prevalence, which is propitious for the implementation of pre-elimination, but data on the extent of malaria importation remain unknown.
  
  
  METHODS
  Djiboutian plasmodial populations were analysed over an eleven-year period (1998, 1999, 2002 and 2009). The risk of malaria importation was indirectly assessed by using plasmodial population parameters. Based on 5 microsatellite markers, expected heterozygosity (H.e.), multiplicity of infection, pairwise Fst index, multiple correspondence analysis and individual genetic relationship were determined. The prevalence of single nucleotide polymorphisms associated with pyrimethamine resistance was also determined.
  
  
  RESULTS
  Data indicated a significant decline in genetic diversity (0.51, 0.59, 0.51 and 0 in 1998, 1999, 2002 and 2009, respectively) over the study period, which is inconsistent with the level of malaria importation described in a previous study. This suggested that Djiboutian malaria situation may have benefited from the decline of malaria prevalence that occurred in neighbouring countries, in particular in Ethiopia. The high Fst indices derived from plasmodial populations from one study period to another (0.12 between 1999 and 2002, and 0.43 between 2002 and 2009) suggested a random sampling of parasites, probably imported from neighbouring countries, leading to oligo-clonal expansion of few different strains during each transmission season. Nevertheless, similar genotypes observed during the study period suggested recurrent migrations and imported malaria.
  
  
  CONCLUSIONS
  In the present study, the extent of genetic diversity was used to assess the risk of malaria importation in the low malaria transmission setting of Djibouti. The molecular approach highlights i) the evolution of Djiboutian plasmodial population profiles that are consistent and compatible with Djiboutian pre-elimination goals and ii) the necessity to implement the monitoring of plasmodial populations and interventions at the regional scale in the Horn of Africa to ensure higher efficiency of malaria control and elimination.
authors.affiliation: Unité de Parasitologie, Département d'Infectiologie de Terrain, Institut de Recherche Biomédicale des Armées, Allée du Médecin Colonel E, Jamot, Parc du Pharo, BP 60109, 13262 Marseille Cedex 07, France.
authors.forename: Bouh Abdi
authors.initials: BA
authors.lastname: Khaireh
authors.forename: Ashenafi
authors.initials: A
authors.lastname: Assefa
authors.forename: Hawa Hassan
authors.initials: HH
authors.lastname: Guessod
authors.forename: Leonardo K
authors.initials: LK
authors.lastname: Basco
authors.forename: Mohamed Abdi
authors.initials: MA
authors.lastname: Khaireh
authors.forename: Aurélie
authors.initials: A
authors.lastname: Pascual
authors.forename: Sébastien
authors.initials: S
authors.lastname: Briolant
authors.forename: Samatar Mohamed
authors.initials: SM
authors.lastname: Bouh
authors.forename: Ismaïl Hassan
authors.initials: IH
authors.lastname: Farah
authors.forename: Habib Moussa
authors.initials: HM
authors.lastname: Ali
authors.forename: Abdoul-Ilah Ahmed
authors.initials: AI
authors.lastname: Abdi
authors.forename: Mouna Osman
authors.initials: MO
authors.lastname: Aden
authors.forename: Zamzam
authors.initials: Z
authors.lastname: Abdillahi
authors.forename: Souleiman Nour
authors.initials: SN
authors.lastname: Ayeh
authors.forename: Houssein Youssouf
authors.initials: HY
authors.lastname: Darar
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Koeck
authors.forename: Christophe
authors.initials: C
authors.lastname: Rogier
authors.forename: Bruno
authors.initials: B
authors.lastname: Pradines
authors.forename: Hervé
authors.initials: H
authors.lastname: Bogreau
mesh_terms: D000962:Antimalarials / Q000494:pharmacology; D016054:DNA, Protozoan / Q000235:genetics; D060740:Disease Eradication; D015730:Djibouti; D004351:Drug Resistance; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000517:prevention & control*; D018895:Microsatellite Repeats; D017720:Molecular Epidemiology; D010963:Plasmodium falciparum / Q000145:classification* / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D011739:Pyrimethamine / Q000494:pharmacology
chemical_list: D000962:Antimalarials; D016054:DNA, Protozoan; D011739:Pyrimethamine