Detection of low‐intensity Schistosoma mansoni infection by Percoll sedimentation and real‐time PCR techniques in a low‐endemicity Egyptian setting

Abstract

Abstractobjective 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 À20°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.

Intestinal schistosomiasis among preschool and school‐aged children in a rural setting near Alexandria: initiative for elimination

“…Two melting temperatures (Tm = 83-87°C, 89-93°C) were identified among the five S. mansonipositive real-time PCR uncured cases that perhaps indicate some sort of mutation (genetic diversity) and different genotype profiles that may be present in S. mansoni in the study area and may lead to PZQ resistance [27,28]. Moreover, the DNA melting temperature also depends on the G-C content of the amplified product [21,29]. Therefore, molecular surveillance approaches using high resolution melting curve analysis should be adopted for future assessment of S. mansoni control programmes.…”

“…A challenging task of adopting other tests with higher sensitivity is constantly brought up [18]. Real-time PCR technique based on SYBR Green was developed for the accurate diagnosis in epidemiological studies of S. mansoni, revealing DNA in foecal samples by using different primers [19][20][21]. Primers of S. mansoni (SmF/SmR) targeting the 28S rDNA region were initially used for its diagnosis in urine samples by Sandoval et al (2006) [13].…”

Antibiofilm Activity of a Trichoderma Metabolite against Xanthomonas campestris pv. campestris, Alone and in Association with a Phage

“…The primers were designed using the tool provided at https://www.eurofinsgenomics.eu/en/ecom/tools/qpcr-assaydesign/ for all genes (Supplementary Table ). Gene transcript levels were measured using Power SYBR Green PCR Master Mix as previously reported [24]. Thermocycler conditions were as follows: initial step at 95 • C for 10 min, 40 cycles of 95 • C for 15 s, (clp 57.1 • C; manA 55 • C, rpf 59.9 • C, gumB 63.7 • C) for 40 s and 72 • C for 1 min.…”

Performance of loop-mediated isothermal amplification (LAMP) for detection of Schistosoma mansoni infection compared with Kato–Katz and real-time PCR

“…Aside from the microscopic Kato–Katz technique, many Schistosoma mansoni diagnostic methods including Percoll, FLOTAC technique on faecal samples (Allam et al ., 2015; Allam et al ., 2021b) and the point-of-care circulating cathodic antigen assay (POC-CCA) in urine samples had been used in Egypt and elsewhere (Allam et al ., 2018; Okoyo et al ., 2018). POC-CCA was reported to display high accuracy and performance in moderate- and high-transmission areas but lacked specificity in low endemic settings in Brazil (Peralta et al ., 2018; Graeff-Teixeira et al ., 2021).…”