title: Diagnostic performance of Schistosoma real-time PCR in urine samples from Kenyan children infected with Schistosoma haematobium: day-to-day variation and follow-up after praziquantel treatment.
abstract: BACKGROUND
  In an effort to enhance accuracy of diagnosis of Schistosoma haematobium, this study explores day-to-day variability and diagnostic performance of real-time PCR for detection and quantification of Schistosoma DNA compared to other diagnostic tools in an endemic area before and after treatment.
  
  
  METHODS
  Previously collected urine samples (N = 390) from 114 preselected proven parasitological and/or clinical S. haematobium positive Kenyan schoolchildren were analyzed by a Schistosoma internal transcribed spacer-based real-time PCR after 14 years of storage. Pre-treatment day-to-day fluctuations of PCR and microscopy over three consecutive days were measured for 24 children using intra-class correlation coefficient. A combined 'gold standard' (PCR and/or microscopy positive) was used to measure sensitivity and negative predictive value (NPV) of several diagnostic tools at baseline, two and 18 months post-treatment with praziquantel.
  
  
  RESULTS
  All 24 repeatedly tested children were PCR-positive over three days with little daily variation in median Ct-values, while 83.3% were found to be egg-positive for S. haematobium at day 1 and 75.0% at day 2 and 3 pre-treatment, signifying daily fluctuations in microscopy diagnosis. Of all 114 preselected schoolchildren, repeated microscopic measurements were required to detect 96.5% versus 100% of positive pre-treatment cases by single PCR. At two months post-treatment, microscopy and PCR detected 22.8% versus 69.3% positive children, respectively. Based on the 'gold standard', PCR showed high sensitivity (>92%) as compared to >31% sensitivity for microscopy, both pre- and post-treatment.
  
  
  CONCLUSIONS
  Detection and quantification of Schistosoma DNA in urine by real-time PCR was shown to be a powerful and specific diagnostic tool for detection of S. haematobium infections, with less day-to-day variation and higher sensitivity compared to microscopy. The superior performance of PCR before, and two and 18 months post-treatment provides a compelling argument for PCR as an accurate and reproducible tool for monitoring treatment efficacy.
authors.affiliation: Leiden University Medical Centre, Department of Parasitology, Centre of Infectious Diseases, Leiden, The Netherlands.
authors.forename: Natalie V S
authors.initials: NV
authors.lastname: Vinkeles Melchers
authors.affiliation: Leiden University Medical Centre, Department of Parasitology, Centre of Infectious Diseases, Leiden, The Netherlands.
authors.forename: Govert J
authors.initials: GJ
authors.lastname: van Dam
authors.affiliation: Leiden University Medical Centre, Department of Parasitology, Centre of Infectious Diseases, Leiden, The Netherlands.
authors.forename: David
authors.initials: D
authors.lastname: Shaproski
authors.affiliation: Division of Vector Borne Diseases, Ministry of Health, Nairobi, Kenya.
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Kahama
authors.affiliation: Leiden University Medical Centre, Department of Parasitology, Centre of Infectious Diseases, Leiden, The Netherlands.
authors.forename: Eric A T
authors.initials: EA
authors.lastname: Brienen
authors.affiliation: Section for Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Birgitte J
authors.initials: BJ
authors.lastname: Vennervald
authors.affiliation: Leiden University Medical Centre, Department of Parasitology, Centre of Infectious Diseases, Leiden, The Netherlands.
authors.forename: Lisette
authors.initials: L
authors.lastname: van Lieshout
mesh_terms: D000293:Adolescent; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use; D002648:Child; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006801:Humans; D007630:Kenya; D008297:Male; D008853:Microscopy; D010274:Parasitology / Q000379:methods*; D011223:Praziquantel / Q000627:therapeutic use; D011237:Predictive Value of Tests; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012189:Retrospective Studies; D012548:Schistosoma haematobium / Q000302:isolation & purification*; D012553:Schistosomiasis haematobia / Q000175:diagnosis* / Q000188:drug therapy / Q000469:parasitology*; D012680:Sensitivity and Specificity; D014556:Urine / Q000469:parasitology*
chemical_list: D000871:Anthelmintics; D021903:DNA, Ribosomal Spacer; D011223:Praziquantel
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