title: Plasmodium prevalence and artemisinin-resistant falciparum malaria in Preah Vihear Province, Cambodia: a cross-sectional population-based study.
abstract: BACKGROUND
  Intensified efforts are urgently needed to contain and eliminate artemisinin-resistant Plasmodium falciparum in the Greater Mekong subregion. Médecins Sans Frontières plans to support the Ministry of Health in eliminating P. falciparum in an area with artemisinin resistance in the north-east of Cambodia. As a first step, the prevalence of Plasmodium spp. and the presence of mutations associated with artemisinin resistance were evaluated in two districts of Preah Vihear Province.
  
  
  METHODS
  A cross-sectional population-based study using a two-stage cluster sampling was conducted in the rural districts of Chhaeb and Chey Saen, from September to October 2013. In each district, 30 clusters of 10 households were randomly selected. In total, blood samples were collected for 1,275 participants in Chhaeb and 1,224 in Chey Saen. Prevalence of Plasmodium spp. was assessed by PCR on dried blood spots. Plasmodium falciparum positive samples were screened for mutations in the K13-propeller domain gene (PF3D7_1343700).
  
  
  RESULTS
  The prevalence of Plasmodium spp. was estimated at 1.49% (95% CI 0.71-3.11%) in Chhaeb and 2.61% (95% CI 1.45-4.66%) in Chey Saen. Twenty-seven samples were positive for P. falciparum, giving a prevalence of 0.16% (95% CI 0.04-0.65) in Chhaeb and 2.04% (95% CI 1.04-3.99%) in Chey Saen. Only 4.0% of the participants testing positive presented with fever or history of fever. K13-propeller domain mutant type alleles (C580Y and Y493H) were found, only in Chey Saen district, in seven out of 11 P. falciparum positive samples with enough genetic material to allow testing.
  
  
  CONCLUSIONS
  The overall prevalence of P. falciparum was low in both districts but parasites presenting mutations in the K13-propeller domain gene, strongly associated with artemisinin-resistance, are circulating in Chey Saen.The prevalence might be underestimated because of the absentees - mainly forest workers - and the workers of private companies who were not included in the study. These results confirm the need to urgently develop and implement targeted interventions to contain and eliminate P. falciparum malaria in this district before it spreads to other areas.
authors.forename: Philippe
authors.initials: P
authors.lastname: Bosman
authors.affiliation: Médecins Sans Frontières, Duprestreet 94, 1090 Brussels, Belgium. jorgenstassijns@yahoo.com.
authors.forename: Jorgen
authors.initials: J
authors.lastname: Stassijns
authors.forename: Fabienne
authors.initials: F
authors.lastname: Nackers
authors.forename: Lydie
authors.initials: L
authors.lastname: Canier
authors.forename: Nimol
authors.initials: N
authors.lastname: Kim
authors.forename: Saorin
authors.initials: S
authors.lastname: Khim
authors.forename: Sweet C
authors.initials: SC
authors.lastname: Alipon
authors.forename: Meng
authors.initials: M
authors.lastname: Chuor Char
authors.forename: Nguon
authors.initials: N
authors.lastname: Chea
authors.forename: Lek
authors.initials: L
authors.lastname: Dysoley
authors.forename: Rafael
authors.initials: R
authors.lastname: Van den Bergh
authors.forename: William
authors.initials: W
authors.lastname: Etienne
authors.forename: Martin
authors.initials: M
authors.lastname: De Smet
authors.forename: Didier
authors.initials: D
authors.lastname: Ménard
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Kindermans
mesh_terms: D000293:Adolescent; D000328:Adult; D000962:Antimalarials / Q000494:pharmacology; D037621:Artemisinins / Q000494:pharmacology; D002160:Cambodia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004351:Drug Resistance; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics; D015995:Prevalence; D055815:Young Adult
chemical_list: D000962:Antimalarials; D037621:Artemisinins; C031327:artemisinin