Real-time PCR for diagnosis of imported schistosomiasis

• Published in: PLoS neglected tropical diseases Vol. 13; no. 9; p. e0007711
• Main Authors: Guegan, Hélène, Fillaux, Judith, Charpentier, Eléna, Robert-Gangneux, Florence, Chauvin, Pamela, Guemas, Emilie, Boissier, Jérôme, Valentin, Alexis, Cassaing, Sophie, Gangneux, Jean-Pierre, Berry, Antoine, Iriart, Xavier
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11-09-2019; Public Library of Science (PLoS)
• Subjects: Animals; Antibodies; Antigens; Antiparasitic agents; Assaying; Biodiversity; Bioindicators; Biological markers; Biology and Life Sciences; Biomarkers; Biopsy; Care and treatment; Deoxyribonucleic acid; Detection; Diagnosis; DNA; DNA, Helminth - analysis; Eggs; Eggs (Food); ELISA; Enzyme-linked immunosorbent assay; Enzymes; Epidemiology; Exploration; Feces - parasitology; Funding; Humans; Infections; Life Sciences; Medicine and Health Sciences; Methods; Microscopy; Nucleotide sequence; Parasites; Parasitic diseases; Parasitology; Patients; PCR; Polymerase chain reaction; Populations and Evolution; Procedures; Public health; Real time; Real-Time Polymerase Chain Reaction - methods; Research and Analysis Methods; Samples; Schistosoma; Schistosoma haematobium - isolation & purification; Schistosoma mansoni - isolation & purification; Schistosomiasis; Schistosomiasis haematobia - blood; Schistosomiasis haematobia - diagnosis; Schistosomiasis haematobia - urine; Schistosomiasis mansoni - blood; Schistosomiasis mansoni - diagnosis; Schistosomiasis mansoni - urine; Sensitivity; Sensitivity and Specificity; Serology; Serum; Specificity; Travel; Tropical diseases; Urine; France; Corsica
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0007711

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.
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).
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.
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.