Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host

Farghaly, Adel; Saleh, Ayman A.; Mahdy, Soad; El-Khalik, Dalia Abd; Fathy, Ghada; Abdelrahman, Sara

doi:10.1007/s12639-014-0583-7

Cited by 13 publications

(18 citation statements)

References 24 publications

(29 reference statements)

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“…Thus, the success of the assay is likely to depend both on snail abundance and infection prevalence. Importantly, all the locations where we identified schistosome-positive snails had much higher rates of infection than is typically observed, which can be around 2% [19], although we recognize that the PCR-based tests of snail infection may have revealed cases of prepatent infections in non-shedding snails [41].…”

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 96%

“…Analyses were conducted using the qPCR approach as described above, although only presence or absence of an amplification is reported herein. We chose a PCR-based screening approach as it allowed us the opportunity to collect the samples in the field and screen the samples at a later date accurately for the focal species; however, the method can amplify individuals with prepatent infections that are not currently shedding cercariae [41]. To confirm the identity of PCR products amplified during these tissue assays, the PCR products from three Biomphalaria pfeifferi samples and three Bulinus globosus samples were Sanger sequenced.…”

Section: Environmental Dna From Aquarium Water Samplesmentioning

confidence: 99%

“…Despite large integrated control programs during the last few decades, disease transmission continues due to the absence of rapid and reliable diagnostic tools to detect the schistosomes in endemic areas [12]. Historically the presence of schistosomes has been established by snail-based surveys coupled with microscopic and/or molecular detection of parasitic larvae within the snails [13][14][15][16][17][18]. These surveys are labour intensive and demand specific training and expertise.…”

Section: Introductionmentioning

confidence: 99%

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Schistosoma species detection by environmental DNA assays in African freshwaters

et al. 2020

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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

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Section: Plos Neglected Tropical Diseasesmentioning

confidence: 96%

Section: Environmental Dna From Aquarium Water Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Schistosoma species detection by environmental DNA assays in African freshwaters

et al. 2020

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“…Another study 23 , also in Pernambuco, showed that of the 64 verified breeding sites of B. straminea, 4 (6.25%) of them had snails releasing cercariae when exposed to artificial light, while the infection of 54 (84.4%) could only be determined by using a molecular biology technique. Other studies have also shown that the method of artificial photostimulation of snails is not able to detect infection in these animals 24 and that molecular techniques are more sensitive in detecting infection of snails by S. mansoni 21,[25][26][27] .…”

Section: Discussionmentioning

confidence: 99%

New epidemiological profile of schistosomiasis from an area of low prevalence in Brazil

Santos

Bezerra

Cirilo

et al. 2020

Rev. Soc. Bras. Med. Trop.

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Introduction: Schistosomiasis, caused by infection from Schistosoma mansoni, is a disease that represents an important public health problem for Brazil, especially for states in the Northeast region. Thus, the aim of this study is to present a new epidemiological profile for the disease in a municipality with low prevalence in the state of Alagoas, Brazil. Methods: A cross-sectional study was conducted through a coproparasitological and malacological survey. A structured questionnaire was applied to the study participants to survey possible risk factors and a spatial analysis (kernel density) was used to measure the risk of infection. Results: Of the 347 participants, 106 (30.5%) were infected by Schistosoma mansoni, most of them from the urban area of the municipality (68.9%; 73/106). A 3-fold risk of infection was found for individuals living in the urban area and a risk of 2.15 times for self-declared farmers. Biomphalaria glabrata and B. straminea were the species found in the municipality, but no animals were diagnosed as infected by the parasite. Spatial analysis showed a random distribution of vectors and human cases of the disease, and the formation of two clusters of human cases in the urban area was seen. Conclusions: A new epidemiological profile for schistosomiasis from S. mansoni infection was presented in a municipality of low endemicity: a high proportion of positive individuals in the urban area; presence of snails without positive diagnosis for S. mansoni infection; random distribution of vectors and human cases; and absence of association between classical risk factors and human infection.

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“…Microscopical examination of schistosome cercariae is then used to determine the infection status of snails [10][11][12], and the method requires considerable time, effort and expertise in the taxonomic identification of schistosome cercariae using microscopy. Alternatively, it is possible to test infection status of individual snails using molecular xenomonitoring tests for the presence of Schistosoma DNA in snail tissue using conventional endpoint PCR [13][14][15][16] or quantitative PCR [17,18]. While these methods requiring testing of individual snails have been very effective, they are limited by the need to test large numbers, as often only a small proportion of a total snail population are infected [19,20].…”

Section: Introductionmentioning

confidence: 99%

Environmental DNA-based xenomonitoring for determining Schistosoma presence in tropical freshwaters

et al. 2020

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Background: Schistosomiasis is a neglected tropical disease that infects over 200 million people worldwide. Control measures can benefit from improved surveillance methods in freshwaters, with environmental DNA (eDNA) surveys having the potential to offer effective and rapid detection of schistosomes. However, sampling eDNA directly from natural water bodies can lead to inaccurate estimation of infection risk if schistosome eDNA is rare in the environment. Here we report a xenomonitoring method that allows schistosome infections of host snail species to be determined from eDNA in water used to house those snails. Methods: Host snail species were collected and placed in containers of water and allowed to shed cercariae, and then water samples were filtered and tested using qPCR assays specific to the African species Schistosoma mansoni and Schistosoma haematobium. We evaluated this "eDNA-based xenomonitoring" approach by experimentally comparing the results to those obtained from direct qPCR screening of tissue sourced from the snails in the experiment. Results: We found that our method accurately diagnosed the presence of S. mansoni-infected snails in all tests, and S. haematobium-infected snails in 92% of tests. Moreover, we found that the abundance of Schistosoma eDNA in experiments was directly dependent on the number and biomass of infected snails. Conclusions: These results provide a strong indication that this surveillance method combining the utility of eDNAbased monitoring with the reliability of traditional xenomonitoring approaches could be used to accurately assay the presence of Schistosoma species in natural habitats. This approach may be well-suited for epidemiological studies and monitoring in endemic areas, where it can assist schistosomiasis control by indicating infection risk from freshwaters and guiding necessary interventions to eliminate the disease.

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Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host

Cited by 13 publications

References 24 publications

Schistosoma species detection by environmental DNA assays in African freshwaters

Schistosoma species detection by environmental DNA assays in African freshwaters

New epidemiological profile of schistosomiasis from an area of low prevalence in Brazil

Environmental DNA-based xenomonitoring for determining Schistosoma presence in tropical freshwaters

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