title: Detection of low-intensity Schistosoma mansoni infection by Percoll sedimentation and real-time PCR techniques in a low-endemicity Egyptian setting.
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.
  
  
  CONCLUSIONS
  Percoll sedimentation and SYBR Green PCR proved useful in detecting low-intensity S. mansoni infections in low-endemicity areas in Egypt.
authors: Department of Parasitology, Medical Research Institute, Alexandria University, Alexandria, Egypt.
authors: Amal F
authors: AF
authors: Allam
authors: Department of Parasitology, Medical Research Institute, Alexandria University, Alexandria, Egypt.
authors: Hoda F
authors: HF
authors: Farag
authors: Department of Medical Statistics, Medical Research Institute, Alexandria University, Alexandria, Egypt.
authors: Adel
authors: A
authors: Zaki
authors: Department of Microbiology, Medical Research Institute, Alexandria University, Alexandria, Egypt.
authors: Ola A
authors: OA
authors: Kader
authors: Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen.
authors: Rashad
authors: R
authors: Abdul-Ghani
authors: Department of Parasitology, Medical Research Institute, Alexandria University, Alexandria, Egypt.
authors: Amel Y
authors: AY
authors: Shehab
keywords: 
  Schistosoma mansoni
  ; Kato-Katz; PCR a tiempo real; PCR en temps réel; Percoll; SYBR Green; Schistosoma mansoni; percoll; real-time PCR