title: Comparison of three methods for detection of gametocytes in Melanesian children treated for uncomplicated malaria.
abstract: BACKGROUND
  Gametocytes are the transmission stages of Plasmodium parasites, the causative agents of malaria. As their density in the human host is typically low, they are often undetected by conventional light microscopy. Furthermore, application of RNA-based molecular detection methods for gametocyte detection remains challenging in remote field settings. In the present study, a detailed comparison of three methods, namely light microscopy, magnetic fractionation and reverse transcriptase polymerase chain reaction for detection of Plasmodium falciparum and Plasmodium vivax gametocytes was conducted.
  
  
  METHODS
  Peripheral blood samples from 70 children aged 0.5 to five years with uncomplicated malaria who were treated with either artemether-lumefantrine or artemisinin-naphthoquine were collected from two health facilities on the north coast of Papua New Guinea. The samples were taken prior to treatment (day 0) and at pre-specified intervals during follow-up. Gametocytes were measured in each sample by three methods: i) light microscopy (LM), ii) quantitative magnetic fractionation (MF) and, iii) reverse transcriptase PCR (RTPCR). Data were analysed using censored linear regression and Bland and Altman techniques.
  
  
  RESULTS
  MF and RTPCR were similarly sensitive and specific, and both were superior to LM. Overall, there were approximately 20% gametocyte-positive samples by LM, whereas gametocyte positivity by MF and RTPCR were both more than two-fold this level. In the subset of samples collected prior to treatment, 29% of children were positive by LM, and 85% were gametocyte positive by MF and RTPCR, respectively.
  
  
  CONCLUSIONS
  The present study represents the first direct comparison of standard LM, MF and RTPCR for gametocyte detection in field isolates. It provides strong evidence that MF is superior to LM and can be used to detect gametocytaemic patients under field conditions with similar sensitivity and specificity as RTPCR.
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Fremantle Hospital, Fremantle, Western Australia, Australia. karl@wehi.edu.au.
authors.forename: Stephan
authors.initials: S
authors.lastname: Karl
authors.forename: Moses
authors.initials: M
authors.lastname: Laman
authors.forename: Tamarah
authors.initials: T
authors.lastname: Koleala
authors.forename: Clemencia
authors.initials: C
authors.lastname: Ibam
authors.forename: Bernadine
authors.initials: B
authors.lastname: Kasian
authors.forename: Nola
authors.initials: N
authors.lastname: N'Drewei
authors.forename: Anna
authors.initials: A
authors.lastname: Rosanas-Urgell
authors.forename: Brioni R
authors.initials: BR
authors.lastname: Moore
authors.forename: Andreea
authors.initials: A
authors.lastname: Waltmann
authors.forename: Cristian
authors.initials: C
authors.lastname: Koepfli
authors.forename: Peter M
authors.initials: PM
authors.lastname: Siba
authors.forename: Inoni
authors.initials: I
authors.lastname: Betuela
authors.forename: Robert C
authors.initials: RC
authors.lastname: Woodward
authors.forename: Timothy G
authors.initials: TG
authors.lastname: St Pierre
authors.forename: Ivo
authors.initials: I
authors.lastname: Mueller
authors.forename: Timothy M E
authors.initials: TM
authors.lastname: Davis
mesh_terms: D000962:Antimalarials / Q000627:therapeutic use; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins / Q000627:therapeutic use; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods; D004338:Drug Combinations; D004983:Ethanolamines / Q000627:therapeutic use; D005260:Female; D005449:Fluorenes / Q000627:therapeutic use; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods*; D007223:Infant; D008288:Malaria / Q000188:drug therapy / Q000469:parasitology*; D008297:Male; D008853:Microscopy / Q000379:methods*; D009285:Naphthoquinones / Q000627:therapeutic use; D010219:Papua New Guinea; D010274:Parasitology / Q000379:methods*; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000302:isolation & purification*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D000962:Antimalarials; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins; D004338:Drug Combinations; D004983:Ethanolamines; D005449:Fluorenes; D009285:Naphthoquinones; C543979:artemisinin-naphthoquine combination