Diagnostic performance of screening methods for urinary schistosomiasis among school children in a school- based antihelminthic programme in Mbozi district

Abstract

Background: Accurate diagnosis for schistosomiasis is crucial for patient management, drug efficacy evaluations, and monitoring of large-scale control programs. However diagnostic performance of screening (indirect) methods vary in different endemic zones, age groups and sexes especially when there is low prevalence after large scale Praziquantel Mass Drug Administration (MDA) in a school based antihelminthic control programme. Main Objective: To evaluate the diagnostic performance of screening (indirect diagnostic) methods for urinary schistosomiasis after wide scale use of praziquantel in a school based antihelminthic control programme in Mbozi District. Materials and methods: A cross-sectional study was conducted in Mbozi District from March to June, 2013. Multistage cluster random sampling was applied to obtain the schools and participants of the study. Twelve schools out of 156 schools (7.7% of all schools) were randomly selected. A total of 429 participants from standard I – VII were chosen proportionally from each selected school. Interviewed questionnaire was used to collect information on demographic characteristics; self reported haematuria, and status of praziquantel administration. Each study participant was provided with 50mls clean, dry wide mouthed and well caped labeled plastic containers for collecting about 20ml of clean-catch, midstream urine sample between 10:00hr and 14:00hr. The diagnostic performance of screening tests were compared with microscopic examination of urine for S. haematobium egg (filtration method, which was regarded as the gold standard) Results: The prevalence of urinary schistosomiasis in Mbozi district was 7.9%, whereby Chemical reagent strip was the most sensitive of all screening methods assessed with sensitivity of (78.8%) also with high NPV (97.8%), followed by self reported haematuria (51.9%), and visual examination of urine was least sensitive of all (42.4%). In terms of specificity, self reported haematuria was the most specific (91.7%) with positive predictive value (34.9%). vi Conclusion: Despite low prevalence of schistosomiasis, chemical reagent strips and self reported haematuria are still useful diagnostic tools for targeting the effect of Praziquantel-MDA to school children in schistosomiasis endemic areas.