Performance of three rapid screening methods in the detection of Schistosoma haematobium infection in school-age children in Southeastern Nigeria

Abstract

Background: A cross-sectional study of primary school children was conducted to evaluate and compare the performance of some rapid screening methods in the detection of Schistosoma haematobium infection in Nigeria Cement Factory (NigerCem) and Nike Lake areas of Southeastern Nigeria.

Methods: Urine samples of school children were examined for macro-haematuria and tested for micro-haematuria and proteinuria using reagent strips followed by egg microscopy. Self-reported haematuria was assessed using simple questionnaire. The performances of these rapid diagnoses singly and in combination were calculated using egg microscopy as gold standard.

Results: The prevalence of the infection was 26·6% in NigerCem and 5·1% in Nike Lake area, classifying these areas as moderate- and low-prevalence areas (MPA and LPA); while in the subsample used for self-reported haematuria, the prevalence was 27·2 and 4·2% in MPA and LPA, respectively. The positive predictive value (PPV) of micro-haematuria was comparable in MPA (55·26%) and LPA (57·89%). Overall PPV of macro-haematuria was 87·50% in MPA and 66·70% in LPA while in the detection of heavy infection; PPV was higher in LPA (75%) than in MPA (66·67%). In LPA and MPA, combination of micro-haematuria and proteinuria, and concomitant presence of macro-haematuria, micro-haematuria, and proteinuria had PPV of 83·33 and 63·16%, and 100 versus 66·67%, respectively. Generally, the rapid screening tests had lower negative predictive values (NPVs) in MPA than in LPA. The use of simple questionnaire increased the PPV of heavy infection in MPA (77·78%). This was further increased to 80% when self-reported haematuria was combined with micro-haematuria.

Conclusion: The result suggests that in MPA with chronic infections, combination of self-reported haematuria and micro-haematuria may reduce the chance of missing those who should be treated.

Keywords: Macro-haematuria,; Predictive values; Questionnaire method,; Reagent strip,; Schistosoma haematobium,.