Prevalence of Schistosoma mansoni using different diangnostic techniques in the Gezira State, Sudan

Abstract

The main objective of this study was to compare different diagnostic methods of Schistosoma mansoni in the Gezira State Sudan during (2005-2007). 438 pupils were selected with mean age 11.42 2.588 (6-20 yrs). 192 (43.9%) were males and 246 (56.2%) were females. All the pupils were examined for Schistosoma mansoni using Kato-Katz technique. A questionnaire as a diagnostic tool was filled by each student. 203 were selected randomly to be examined by ultrasound (U/S). Fifty S. mansoni negative stool samples were examined by Polymerase Chain Reaction (PCR). The present study showed that prevalence of S. mansoni was 29.2% by Kato-Katz technique, 27.2% by questionnaire, 50.5% by ultra sonography (U/S), and 26% by PCR. The sensitivity and specificity of the questionnaire was 34.4% and 75.8% respectively (p=0.0256), with positive predictive value (PPV) equal to 37%. Ultrasound sensitivity was 54.4% and the specificity was 51.0% (P=0.591) with a PPV of 30%. The sensitivity of PCR was 100% while the specificity was 74% with a PPV 18% (p=0.023). The study revealed that questionnaire was a good test for screening and identification of the exposure and infection, but ultrasonography cannot be used as a diagnosing technique. PCR was considered the best diagnostic tool for confirmation of S. mansoni infection. The study recommended the use of the PCR for S. mansoni diagnosis and the possibility of using Questionnaire as screening tools for this parasite in a sustainable control program.