ABSTRACT
OBJECTIVE: To evaluate the performance of Percoll sedimentation and real-time polymerase chain reaction (PCR) for the detection of S. mansoni cases previously tested as negative by Kato-Katz technique in two low-endemic areas in Alexandria, Egypt, Abis 4 and 8 villages. METHODS: Stool samples of 824 primary schoolchildren were examined by Kato-Katz technique (three slides of 41.7 mg each). After obtaining the results of this survey, stool samples were recollected from a subset of 150 students, who gave negative results after Kato-Katz. These samples were microscopically examined after the concentration with Percoll technique. Part of the 150 negative stool samples and five positive samples (used as controls) were kept at -20 °C and further processed by SYBR Green PCR. RESULTS: Prevalence of S. mansoni infection as determined by three Kato-Katz thick smears was 1.82% (15 cases). Three more cases tested positive by Percoll sedimentation among the 150 samples that were negative by Kato-Katz. Specific amplification by SYBR Green PCR was noted in all positive controls and in three cases of Kato-Katz-negative samples, two of which were also positive by Percoll. CONCLUSION: Percoll sedimentation and SYBR Green PCR proved useful in detecting low-intensity S. mansoni infections in low-endemicity areas in Egypt.