Real-time PCR for diagnosis of imported schistosomiasis

Type Article
Date 2019-09
Language English
Author(s) Guegan Hélène1, Fillaux Judith2, Charpentier Elena3, Robert-Gangneux Florence4, Chauvin Pamela5, Guemas Emilie6, Boissier Jérôme7, Valentin Alexis8, Cassaing Sophie9, Gangneux Jean-Pierre10, Berry Antoine11, Iriart Xavier12
Affiliation(s) 1 : Univ Rennes, CHU Rennes, Inserm, EHESP, IRSET (Institut de Recherche en Santé Environnement et Travail) – UMR_S 1085, Rennes, France, Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
2 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
3 : Université de Toulouse, CNRS, INSERM, UPS, Toulouse, France
4 : Univ Rennes, CHU Rennes, Inserm, EHESP, IRSET (Institut de Recherche en Santé Environnement et Travail) – UMR_S 1085, Rennes, France
5 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
6 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
7 : Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
8 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
9 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France
10 : Univ Rennes, CHU Rennes, Inserm, EHESP, IRSET (Institut de Recherche en Santé Environnement et Travail) – UMR_S 1085, Rennes, France
11 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France, Centre de Physiopathologie de Toulouse Purpan (CPTP), Université de Toulouse, CNRS, INSERM, UPS, Toulouse, France
12 : Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France, Centre de Physiopathologie de Toulouse Purpan (CPTP), Université de Toulouse, CNRS, INSERM, UPS, Toulouse, France
Source Plos Neglected Tropical Diseases (1935-2735) (Public Library of Science (PLoS)), 2019-09 , Vol. 13 , N. 9 , P. e0007711 (18p.)
DOI 10.1371/journal.pntd.0007711
WOS© Times Cited 12
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. Author summary Schistosomiasis is one of the most important human parasitic neglected tropical diseases. It is a major source of morbidity and mortality in Africa but also in South America, the Caribbean, the Middle East, and Asia. It is transmitted by skin penetration of schistosome cercariae via contact with freshwater. Schistosoma mansoni and S. haematobium are the most common species and are frequent causes of infection in travelers and migrants returning from endemic areas. Chronic infections with these two species can cause irreversible damage to the liver or genitourinary tract. Diagnosis mainly relies on serological screening and microscopic procedures from urine and stool specimens that can, however, fail to detect low parasite burden and depend on operator competence. So there is a need to improve the detection of this disease. With this retrospective study, we evaluate the accuracy of a specific Schistosoma PCR assay for the diagnosis of schistosomiasis on a large cohort of migrants and travelers returning from endemic areas. Our study showed that PCR, a technique allowing Schistosoma DNA amplification and detection, greatly improved the diagnosis of both parasite species in urine, feces and biopsies. We also demonstrate that the detection of circulating Schistosoma DNA in blood by PCR is useful to confirm schistosomiasis diagnosis, to provide a species identification when the microscopy research is negative and to monitor the treatment efficacy.
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Guegan Hélène, Fillaux Judith, Charpentier Elena, Robert-Gangneux Florence, Chauvin Pamela, Guemas Emilie, Boissier Jérôme, Valentin Alexis, Cassaing Sophie, Gangneux Jean-Pierre, Berry Antoine, Iriart Xavier (2019). Real-time PCR for diagnosis of imported schistosomiasis. Plos Neglected Tropical Diseases, 13(9), e0007711 (18p.). Publisher's official version : https://doi.org/10.1371/journal.pntd.0007711 , Open Access version : https://archimer.ifremer.fr/doc/00514/62534/