Radwa Galal Diab1, Rasha Fadly Mady1, Mona Mohamed Tolba2, Rasha Abdelmawla Ghazala3. 1. Medical Parasitology Department, Faculty of Medicine, University of Alexandria, Alexandria, Egypt. 2. Parasitology Department, Medical Research Institute, University of Alexandria, Alexandria, Egypt. 3. Medical Biochemistry Department, Faculty of Medicine, University of Alexandria, Alexandria, Egypt.
Abstract
OBJECTIVE: To evaluate three non-invasive assays for the diagnosis of schistosomiasis mansoni in an Egyptian village. METHODS: Urine was collected for the detection of circulating cathodic antigen (CCA) and cell-free parasite DNA (cfpd) by Point-of-contact (POC)-cassette assay and PCR, respectively. These tests were compared to Kato-Katz (KK) faecal thick smear for detection of Schistosoma mansoni eggs. RESULTS: Disease prevalence by POC-CCA assay was 86%; by PCR it was 39% vs. 27% by KK. Compared to KK, the sensitivity of POC-CCA reached 100%, but its specificity was only 19.2% with 41% accuracy. Sensitivity of the PCR assay for cfpd was 55.56%, and specificity was 67.12% with 64% accuracy. A new end point was calculated for combined analysis of KK, POC-CCA assay and PCR. Sensitivity for the three tests was 52.94%, 90.2% and 76.47%; specificity was 100% for KK and PCR and 18.37% for POC-CCA. The accuracy calculated for the three tests at the end point was 76% for KK, 55% for POC-CCA assay and 88% for PCR. CONCLUSION: Conventional PCR assay for detection of cfpd provides a potential screening tool for intestinal schistosomiasis with reliable specificity, reasonable accuracy and affordable financial and technical cost.
OBJECTIVE: To evaluate three non-invasive assays for the diagnosis of schistosomiasis mansoni in an Egyptian village. METHODS: Urine was collected for the detection of circulating cathodic antigen (CCA) and cell-free parasite DNA (cfpd) by Point-of-contact (POC)-cassette assay and PCR, respectively. These tests were compared to Kato-Katz (KK) faecal thick smear for detection of Schistosoma mansoni eggs. RESULTS: Disease prevalence by POC-CCA assay was 86%; by PCR it was 39% vs. 27% by KK. Compared to KK, the sensitivity of POC-CCA reached 100%, but its specificity was only 19.2% with 41% accuracy. Sensitivity of the PCR assay for cfpd was 55.56%, and specificity was 67.12% with 64% accuracy. A new end point was calculated for combined analysis of KK, POC-CCA assay and PCR. Sensitivity for the three tests was 52.94%, 90.2% and 76.47%; specificity was 100% for KK and PCR and 18.37% for POC-CCA. The accuracy calculated for the three tests at the end point was 76% for KK, 55% for POC-CCA assay and 88% for PCR. CONCLUSION: Conventional PCR assay for detection of cfpd provides a potential screening tool for intestinal schistosomiasis with reliable specificity, reasonable accuracy and affordable financial and technical cost.