Schistosoma species detection by environmental DNA assays in African freshwaters

Abstract

Background Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may benefit from specific and sensitive diagnostic methods to detect Schistosoma trematodes in aquatic environments. Here we report the development of novel environmental DNA (eDNA) qPCR assays for the presence of the human-infecting species Schistosoma mansoni, S. haematobium and S. japonicum. Methodology/Principal findings We first tested the specificity of the assays across the three species using genomic DNA preparations which showed successful amplification of target sequences with no cross amplification between the three focal species. In addition, we evaluated the specificity of the assays using synthetic DNA of multiple Schistosoma species, and demonstrated a high overall specificity; however, S. japonicum and S. haematobium assays showed cross-species amplification with very closely-related species. We next tested the effectiveness of the S. mansoni assay using eDNA samples from aquaria containing infected host gastropods, with the target species revealed as present in all infected aquaria. Finally, we evaluated the effectiveness of the S. mansoni and S. haematobium assays using eDNA samples from eight discrete natural freshwater sites in Tanzania, and demonstrated strong correspondence between infection status established using eDNA and conventional assays of parasite prevalence in host snails. Conclusions/Significance Collectively, our results suggest that eDNA monitoring is able to detect schistosomes in freshwater bodies, but refinement of the field sampling, storage and assay methods are PLOS NEGLECTED TROPICAL DISEASES

Detecting and identifying Schistosoma infections in snails and aquatic habitats: A systematic review

“…As noted in Table 3 , there are pros and cons to each. One notable development to go along with the increasing use of eDNA is qPCR-based technology to analyze extracted specimens [ 20 – 24 ]. A quenchable fluorescent probe designed to detect a particular sequence of the target organism of interest is typically included (FRET-qPCR).…”

Polarization of intestinal tumour-associated macrophages regulates the development of schistosomal colorectal cancer

“…Moreover, the proportion of patients older than 60 years in the schistosomal group was significantly higher compared to the nonschistosomal group (P=0.002). Both groups had more males than females, but the proportion of males in the schistosomal group was significantly higher compared to the non-schistosomal group (P=0.001), which may be due to differences in water exposure or diet [21,22]. Studies have shown that dietary intakes differ between women and men [23].…”

Schistosoma mansoni Vector Snails in Antigua and Montserrat, with Snail-Related Considerations Pertinent to a Declaration of Elimination of Human Schistosomiasis

“…Environmental DNA (eDNA) methods particularly offer promise for detecting the presence of either vector snails or schistosomes in water samples. [44][45][46] Environmental DNA offers the advantages that signals in water samples are integrated across time and space permitting broader coverage, and specific identifications based on DNA sequences recovered can be acquired if desired. In our view, increased use of eDNA approaches is an important goal for future surveys.…”