title: Plasmodium vivax populations are more genetically diverse and less structured than sympatric Plasmodium falciparum populations.
abstract: BACKGROUND
  The human malaria parasite, Plasmodium vivax, is proving more difficult to control and eliminate than Plasmodium falciparum in areas of co-transmission. Comparisons of the genetic structure of sympatric parasite populations may provide insight into the mechanisms underlying the resilience of P. vivax and can help guide malaria control programs.
  
  
  RESULTS
  P. vivax isolates representing the parasite populations of four areas on the north coast of Papua New Guinea (PNG) were genotyped using microsatellite markers and compared with previously published microsatellite data from sympatric P. falciparum isolates. The genetic diversity of P. vivax (He = 0.83-0.85) was higher than that of P. falciparum (He = 0.64-0.77) in all four populations. Moderate levels of genetic differentiation were found between P. falciparum populations, even over relatively short distances (less than 50 km), with 21-28% private alleles and clear geospatial genetic clustering. Conversely, very low population differentiation was found between P. vivax catchments, with less than 5% private alleles and no genetic clustering observed. In addition, the effective population size of P. vivax (30353; 13043-69142) was larger than that of P. falciparum (18871; 8109-42986).
  
  
  CONCLUSIONS
  Despite comparably high prevalence, P. vivax had higher diversity and a panmictic population structure compared to sympatric P. falciparum populations, which were fragmented into subpopulations. The results suggest that in comparison to P. falciparum, P. vivax has had a long-term large effective population size, consistent with more intense and stable transmission, and limited impact of past control and elimination efforts. This underlines suggestions that more intensive and sustained interventions will be needed to control and eventually eliminate P. vivax. This research clearly demonstrates how population genetic analyses can reveal deeper insight into transmission patterns than traditional surveillance methods.
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
authors: Charlie
authors: C
authors: Jennison
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
authors: Alicia
authors: A
authors: Arnott
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
authors: Natacha
authors: N
authors: Tessier
authors: Papua New Guinea Institute for Medical Research, Goroka, Eastern Highlands Province, Papua New Guinea.
authors: Livingstone
authors: L
authors: Tavul
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
authors: Cristian
authors: C
authors: Koepfli
authors: Swiss Tropical and Public Health Institute, Basel, Switzerland.
authors: Ingrid
authors: I
authors: Felger
authors: Papua New Guinea Institute for Medical Research, Goroka, Eastern Highlands Province, Papua New Guinea.
authors: Peter M
authors: PM
authors: Siba
authors: Centre for Population Health, Burnet Institute, Melbourne, Victoria, Australia.
authors: John C
authors: JC
authors: Reeder
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia; Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia.
authors: Melanie
authors: M
authors: Bahlo
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Barcelona Centre for International Health Research, Barcelona, Spain.
authors: Ivo
authors: I
authors: Mueller
authors: Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
authors: Alyssa E
authors: AE
authors: Barry
mesh_terms: D000483:Alleles; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D008288:Malaria / Q000453:epidemiology* / Q000469:parasitology / Q000517:prevention & control*; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010219:Papua New Guinea / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000235:genetics*; D010966:Plasmodium vivax / Q000235:genetics*; D015995:Prevalence