Dataset Information

Real-time PCR for diagnosis of imported schistosomiasis.

ABSTRACT:

Background

The diagnosis of schistosomiasis currently relies on microscopic detection of schistosome eggs in stool or urine samples and serological assays. The poor sensitivity of standard microscopic procedures performed in routine laboratories, makes molecular detection methods of increasing interest. The aim of the study was to evaluate two in-house real-time Schistosoma PCRs, targeting respectively S. mansoni [Sm] and S. haematobium [Sh] in excreta, biopsies and sera as potential tools to diagnose active infections and to monitor treatment efficacy.

Methods

Schistosoma PCRs were performed on 412 samples (124 urine, 86 stools, 8 biopsies, 194 sera) from patients with suspected schistosomiasis, before anti-parasitic treatment. Results were compared to microscopic examination and serological assays (enzyme-linked immunosorbent assay (ELISA), indirect haemagglutination (HA) and Western Blot (WB) assay).

Results

Compared to microscopy, PCRs significantly increased the sensitivity of diagnosis, from 4% to 10.5% and from 33.7% to 48.8%, for Sh in urine and Sm in stools, respectively. The overall sensitivity of PCR on serum samples was 72.7% and reached 94.1% in patients with positive excreta (microscopy). The specificity of serum PCR was 98.9%. After treatment, serum PCR positivity rates slowly declined from 93.8% at day 30 to 8.3% at day 360, whereas antibody detection remained positive after 1 year.

Conclusion

Schistosoma PCRs clearly outperform standard microscopy on stools and urine and could be part of reference methods combined with WB-based serology, which remains a gold standard for initial diagnosis. When serological assays are positive and microscopy is negative, serum PCRs provide species information to guide further clinical exploration. Biomarkers such as DNA and antibodies are of limited relevance for early treatment monitoring but serum PCR could be useful when performed at least 1 year after treatment to help confirm a cured infection.

SUBMITTER: Guegan H

PROVIDER: S-EPMC6756557 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Publications

Real-time PCR for diagnosis of imported schistosomiasis.

Guegan Hélène H Fillaux Judith J Charpentier Eléna E Robert-Gangneux Florence F Chauvin Pamela P Guemas Emilie E Boissier Jérôme J Valentin Alexis A Cassaing Sophie S Gangneux Jean-Pierre JP Berry Antoine A Iriart Xavier X

PLoS neglected tropical diseases 20190911 9

<h4>Background</h4>The diagnosis of schistosomiasis currently relies on microscopic detection of schistosome eggs in stool or urine samples and serological assays. The poor sensitivity of standard microscopic procedures performed in routine laboratories, makes molecular detection methods of increasing interest. The aim of the study was to evaluate two in-house real-time Schistosoma PCRs, targeting respectively S. mansoni [Sm] and S. haematobium [Sh] in excreta, biopsies and sera as potential too ...[more]

PMID: 31509538

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Project description:The laboratorial diagnosis of the intestinal schistosomiasis is always performed using Kato-Katz technique. However, this technique presents low sensitivity for diagnosis of individuals with low parasite burden, which constitutes the majority in low endemicity Brazilian locations for the disease. The objective of this study was developed and to validate a real-time PCR assay (qPCR) targeting 121 bp sequence to detect Schistosoma spp. DNA for the diagnosis of intestinal schistosomiasis and a sequence of the human β-actin gene as internal control. Firstly, the qPCR was standardized and next it was evaluated for diagnosis and cure assessment of intestinal schistosomiasis in the resident individuals in Tabuas and Estreito de Miralta, two locations in Brazil endemic for intestinal schistosomiasis. The qPCR assay results were compared with those of the Kato-Katz (KK) test, examining 2 or 24 slides, Saline Gradient (SG) and "reference test" (24 KK slides + SG). The cure assessment was measured by these diagnostic techniques at 30, 90, and 180 days post-treatment. In Tabuas, the positivity rates obtained by the qPCR was 30.4% (45/148) and by "reference test" was of 31.0% (46/148), with no statistical difference (p = 0.91). The presumed cure rates at 30, 90, and 180 days post-treatment were 100, 94.4, and 78.4% by the analysis of 24 KK slides, 100, 94.4, and 78.4% by the SG, and 100, 83.3, and 62.1% by the qPCR assay. In Estreito de Miralta, the positivity obtained by qPCR was 18.3% (26/142) and with "reference test" was 24.6% (35/142), with no statistical difference (p = 0.20). The presumed cure rates were 93.3, 96.9, and 96.5% by the KK, 93.3, 96.9, and 100% by the SG, and 93.3, 93.9, and 96.5% by the qPCR at 30, 90, and 180 days post-treatment, respectively. This study showed that the diagnostic techniques presented different performance in the populations from the two districts (Tabuas and Estreito de Miralta) and reinforces the need of combining techniques to improve diagnosis accuracy, increasing the detection of individuals with low parasite burden. This combination of techniques consists an important strategy for controlling the disease transmission.

Project description:BACKGROUND: Nucleic acid amplification of the IS481 region by PCR is more sensitive than culture for detection and diagnosis of Bordetella pertussis but the assay has known cross-reactivity for Bordetella holmesii and its use as a routine diagnostic assay has not been widely evaluated. METHODS: The objectives of this study were: 1) to assess the diagnostic utility of real-time IS481 PCR by comparison of results with culture and direct fluorescent antigen (DFA) testing for B. pertussis, 2) to employ a PCR assay designed against a different insertion sequence (IS1001) to assess the incidence of B. holmesii in symptomatic individuals and 3) to design and evaluate a new PCR-based assay which could be used for B. pertussis confirmation. A total of 808 nasopharyngeal specimens were included in the study the majority of which were submitted in charcoal transport medium (88%) with the rest submitted in Regan-Lowe medium. RESULTS: Concordant results for PCR, DFA and culture were obtained for 21 B. pertussis positive and 729 B. pertussis negative specimens. DFA was prone to false positive and negative reactions when compared with both PCR and culture. The IS481 PCR identified 28 positive results for specimens that were DFA and culture negative. A novel real-time PCR targeting the B. pertussis toxin promoter was found to be specific and useful for confirming the majority of IS481 positive specimens as B. pertussis. B. holmesii was not detected in any of the submitted samples. CONCLUSION: The potential pick up of B. holmesii by the IS481 PCR had minimal diagnostic relevance in the Alberta population during the time period of our study. The IS481 PCR assay is now used in our laboratory routinely for front-line screening of samples for B. pertussis with associated enhancement in diagnostic sensitivity compared with DFA and culture. Retrospectively, patients' samples are batched and tested by the IS1001 MB and TPR assays for research purposes and to ensure there is no change in B. holmesii incidence in the population.

Dataset Information

Real-time PCR for diagnosis of imported schistosomiasis.

Background

Methods

Results

Conclusion

Publications

Real-time PCR for diagnosis of imported schistosomiasis.

Similar Datasets

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