title: Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands.
abstract: BACKGROUND
  Temotu Province, Solomon Islands is progressing toward malaria elimination. A baseline survey conducted in 2008 showed that most Plasmodium infections in the province were of low parasite density and asymptomatic infections. To better understand mechanisms underlying these malaria transmission characteristics genetic diversity and relationships among Plasmodium falciparum and Plasmodium vivax populations in the province were examined.
  
  
  METHODS
  Forty-five P. falciparum and 67 P. vivax samples collected in the 2008 baseline survey were successfully genotyped using eight P. falciparum and seven P. vivax microsatellite markers. Genetic diversity, relationships and distribution of both P. falciparum and P. vivax populations were analysed.
  
  
  RESULTS
  Plasmodium falciparum population exhibited low diversity with 19 haplotypes identified and had closely related clusters indicating clonal expansion. Interestingly, a dominant haplotype was significantly associated with fever and high parasite density. In contrast, the P. vivax population was highly diverse with 58 haplotypes identified that were not closely related. Parasite populations between different islands in the province showed low genetic differentiation.
  
  
  CONCLUSIONS
  The low diversity and clonal population of P. falciparum population may partially account for clinical immunity developed against illness. However, it is possible that importation of a new P. falciparum strain was the major cause of illness. High diversity in P. vivax population and low relatedness between strains suggested clinical immunity to P. vivax may be maintained by different mechanisms. The genetic diversity, population structure and distribution of strains indicate that transmission of P. falciparum was low, but that of P. vivax was still high in 2008. These data will be useful for assessing changes in malaria transmission resulting from interventions.
authors.affiliation: Drug Resistance and Diagnostics, Australian Army Malaria Institute, Weary Dunlop Drive, Gallipoli Barracks, Enoggera, QLD, 4051, Australia. qin.cheng@defence.gov.au.
authors.forename: Karen-Ann
authors.initials: KA
authors.lastname: Gray
authors.forename: Simone
authors.initials: S
authors.lastname: Dowd
authors.forename: Lisa
authors.initials: L
authors.lastname: Bain
authors.forename: Albino
authors.initials: A
authors.lastname: Bobogare
authors.forename: Lyndes
authors.initials: L
authors.lastname: Wini
authors.forename: G Dennis
authors.initials: GD
authors.lastname: Shanks
authors.forename: Qin
authors.initials: Q
authors.lastname: Cheng
mesh_terms: D058070:Asymptomatic Diseases / Q000453:epidemiology; D003430:Cross-Sectional Studies; D016054:DNA, Protozoan / Q000032:analysis; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology*; D016780:Malaria, Vivax / Q000453:epidemiology / Q000469:parasitology*; D008542:Melanesia / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics*; D010966:Plasmodium vivax / Q000145:classification / Q000235:genetics*
chemical_list: D016054:DNA, Protozoan