title: Further Evidence of Increasing Diversity of Plasmodium vivax in the Republic of Korea in Recent Years.
abstract: BACKGROUND
  Vivax malaria was successfully eliminated from the Republic of Korea (ROK) in the late 1970s but re-emerged in 1993. Two decades later as the ROK enters the final stages of malaria elimination, dedicated surveillance of the local P. vivax population is critical. We apply a population genetic approach to gauge P. vivax transmission dynamics in the ROK between 2010 and 2012.
  
  
  RESULTS
  P. vivax positive blood samples from 98 autochthonous cases were collected from patients attending health centers in the ROK in 2010 (n = 27), 2011 (n = 48) and 2012 (n = 23). Parasite genotyping was undertaken at 9 tandem repeat markers. Although not reaching significance, a trend of increasing population diversity was observed from 2010 (HE = 0.50 ± 0.11) to 2011 (HE = 0.56 ± 0.08) and 2012 (HE = 0.60 ± 0.06). Conversely, linkage disequilibrium declined during the same period: IAS = 0.15 in 2010 (P = 0.010), 0.09 in 2011 (P = 0.010) and 0.05 in 2012 (P = 0.010). In combination with data from other ROK studies undertaken between 1994 and 2007, our results are consistent with increasing parasite divergence since re-emergence. Polyclonal infections were rare (3% infections) suggesting that local out-crossing alone was unlikely to explain the increased divergence. Cases introduced from an external reservoir may therefore have contributed to the increased diversity. Aside from one isolate, all infections carried a short MS20 allele (142 or 149 bp), not observed in other studies in tropical endemic countries despite high diversity, inferring that these regions are unlikely reservoirs.
  
  
  CONCLUSIONS
  Whilst a number of factors may explain the observed population genetic trends, the available evidence suggests that an external geographic reservoir with moderate diversity sustains the majority of P. vivax infection in the ROK, with important implications for malaria elimination.
authors.affiliation: Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea.
authors.forename: Jung-Yeon
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea.|Department of Parasitology and Tropical Medicine, Kyungpook National University School of Medicine, Daegu, 700-422, Republic of Korea.
authors.forename: Youn-Kyoung
authors.initials: YK
authors.lastname: Goo
authors.affiliation: Department of Molecular Parasitology, Sungkyunkwan University School of Medicine and Center for Molecular Medicine, Samsung Biomedical Research Institute, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Young-Gun
authors.initials: YG
authors.lastname: Zo
authors.affiliation: Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Ji
authors.affiliation: Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta Pusat, 10430, Indonesia.|Agency for Assessment and Application of Technology, Jl. MH Thamrin 8, Jakarta, 10340, Indonesia.
authors.forename: Hidayat
authors.initials: H
authors.lastname: Trimarsanto
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia.
authors.forename: Sheren
authors.initials: S
authors.lastname: To
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom.|Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom.
authors.forename: Taane G
authors.initials: TG
authors.lastname: Clark
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia.|Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Ric N
authors.initials: RN
authors.lastname: Price
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Auburn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D015810:Linkage Disequilibrium; D016780:Malaria, Vivax / Q000469:parasitology*; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D010966:Plasmodium vivax / Q000235:genetics* / Q000472:pathogenicity; D056910:Republic of Korea; D055815:Young Adult