title: Malaria prevalence defined by microscopy, antigen detection, DNA amplification and total nucleic acid amplification in a malaria-endemic region during the peak malaria transmission season.
abstract: OBJECTIVE
  To determine the malaria prevalence by microscopy, antigen detection and nucleic acid detection in a defined subpopulation in a Plasmodium falciparum-endemic region during the peak transmission season.
  
  
  METHODS
  Blood specimens were collected in a cross-sectional study involving children aged 5-10 years (n = 195) presenting with acute fever to two clinics in Western Kenya. All specimens underwent microscopy, HRP2 and aldolase antigen detection by enzyme immunoassay (EIA), parasite-specific DNA and total nucleic acid (RNA and DNA) by real-time PCR (qPCR) and reverse-transcriptase PCR (qRT-PCR).
  
  
  RESULTS
  Microscopy detected 65/195 cases of malaria infection [95% confidence interval (CI) 52-78]. HRP2 and aldolase EIA had similar sensitivity levels detecting antigen in 65/195 (95% CI, 52-78) and 57/195 (95% CI, 45-70) cases. Discordants in antigen detection vs. microscopy occurred at <470 parasites/μl and <4900 parasites/μl for HRP2 and aldolase, respectively. Detection of total nucleic acid allowed a 3 log lower limit of detection than just DNA detection by real-time PCR in vitro. In clinical specimens, 114/195 (95% CI, 100-127) were qPCR positive (DNA), and 187/195 (95% CI, 179-191) were qRT-PCR positive (DNA plus RNA).
  
  
  CONCLUSIONS
  The prevalence of submicroscopic malaria infection was significantly higher when detecting total nucleic acid than just DNA in this outpatient population during the high transmission season. Defining standards for submicroscopic infection will be important for control programmes, diagnostics development efforts and molecular epidemiology studies.
authors: Walter Reed Project, Kenya Medical Research Institute, Kisumu, Kenya.
authors: John N
authors: JN
authors: Waitumbi
authors: Jay
authors: J
authors: Gerlach
authors: Irina
authors: I
authors: Afonina
authors: Samuel B
authors: SB
authors: Anyona
authors: Joseph N
authors: JN
authors: Koros
authors: Joram
authors: J
authors: Siangla
authors: Irina
authors: I
authors: Ankoudinova
authors: Mitra
authors: M
authors: Singhal
authors: Kate
authors: K
authors: Watts
authors: Mark E
authors: ME
authors: Polhemus
authors: Nicolaas M
authors: NM
authors: Vermeulen
authors: Walt
authors: W
authors: Mahoney
authors: Matt
authors: M
authors: Steele
authors: Gonzalo J
authors: GJ
authors: Domingo
mesh_terms: D000953:Antigens, Protozoan / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D016054:DNA, Protozoan / Q000302:isolation & purification*; D019353:Endemic Diseases; D005260:Female; D005634:Fructose-Bisphosphate Aldolase / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D007630:Kenya / Q000453:epidemiology; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D008853:Microscopy; D021141:Nucleic Acid Amplification Techniques; D010270:Parasite Egg Count; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D015995:Prevalence; D015800:Protozoan Proteins / Q000302:isolation & purification*; D016053:RNA, Protozoan / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000953:Antigens, Protozoan; D016054:DNA, Protozoan; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D005634:Fructose-Bisphosphate Aldolase