Amal F. Allam
Alexandria University, Egypt
Amal Farahat Mohamed Allam is an acting Dean of medical Research Institute, Alexandria University she is also the Vice Dean of community service and environmental affairs & Professor of Parasitology in Parasitology Department. She published her papers in many international Journals. She participates in many national health education campaigns and help in the treatment of poor population.
Objective: To compare the performance of urine circulating cathodic antigen (CCA) cassette test and real time PCR cycle threshold values in cases of Schistosomaisis mansoni of different infection intensities.
Methods: Stool and urine samples were collected from 110 school children after obtaining the consent of school guardians and children’s parents. Stool samples were microscopically examined using double Kato slides (41.7 mg each). Midstream urine specimens were tested for S. mansoni by using CCA and were tested for S. haematobium by filtration technique . Part of each stool sample was kept at -20 °C and further processed by SYBR Green PCR.
Results: All the examined cases were negative for S. haematobium. In spite of the high prevalence of S.mansoni , the majority of children had light infection intensity (64.3%) as estimated by Kato- Katz. The highest infection rate of S. mansoni was detected by real time PCR (82.7%), followed by CCA test (60%) while the lowest infection rate was diagnosed by Kato-Katz (50.9%). The three tests showed similar performance in moderate and heavy infections. On the contrary, among the 54 negative schistosomiasis individuals after Kato-Katz, real time PCR diagnosed higher positive cases (70%) in comparison to CCA (22%). Cycle threshold values higher than 25, suggest the absence of heavy infection.
Conclusion: Real time PCR was the most detector of positive S. mansoni cases missed by Kato- Katz and CCA test and it would enhance the effectiveness of surveillance and control programs of schistosomiasis. To detect low infection intensity and missed cases after Kato- Katz, it is recommended to increase the cycle threshold during application of real time PCR to 40 cycles.
Keywords: Schistosoma mansoni, Kato-Katz, circulating cathodic antigen (CCA) cassette test, SYBR Green, real-time PCR.