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

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.methodology: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.principal findings: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/significance: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. © 2014 vinkeles melchers et al.