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PLoS Neglected Tropical Diseases Sep 2021Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa, where people may be co-infected with more than one species of the...
Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa, where people may be co-infected with more than one species of the parasite. Infection risk for any single species is determined, in part, by the distribution of its obligate intermediate host snail. As the World Health Organization reprioritizes snail control to reduce the global burden of schistosomiasis, there is renewed importance in knowing when and where to target those efforts, which could vary by schistosome species. This study estimates factors associated with schistosomiasis risk in 16 villages located in the Senegal River Basin, a region hyperendemic for Schistosoma haematobium and S. mansoni. We first analyzed the spatial distributions of the two schistosomes' intermediate host snails (Bulinus spp. and Biomphalaria pfeifferi, respectively) at village water access sites. Then, we separately evaluated the relationships between human S. haematobium and S. mansoni infections and (i) the area of remotely-sensed snail habitat across spatial extents ranging from 1 to 120 m from shorelines, and (ii) water access site size and shape characteristics. We compared the influence of snail habitat across spatial extents because, while snail sampling is traditionally done near shorelines, we hypothesized that snails further from shore also contribute to infection risk. We found that, controlling for demographic variables, human risk for S. haematobium infection was positively correlated with snail habitat when snail habitat was measured over a much greater radius from shore (45 m to 120 m) than usual. S. haematobium risk was also associated with large, open water access sites. However, S. mansoni infection risk was associated with small, sheltered water access sites, and was not positively correlated with snail habitat at any spatial sampling radius. Our findings highlight the need to consider different ecological and environmental factors driving the transmission of each schistosome species in co-endemic landscapes.
Topics: Adolescent; Adult; Animal Distribution; Animals; Child; Disease Reservoirs; Ecosystem; Female; Humans; Male; Middle Aged; Rivers; Rural Population; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis haematobia; Schistosomiasis mansoni; Senegal; Snails; Young Adult
PubMed: 34570777
DOI: 10.1371/journal.pntd.0009712 -
PLoS Neglected Tropical Diseases Mar 2022Female genital schistosomiasis (FGS) is a neglected and disabling gynecological disease that can result from infection with the parasitic trematode Schistosoma...
Validation of the isothermal Schistosoma haematobium Recombinase Polymerase Amplification (RPA) assay, coupled with simplified sample preparation, for diagnosing female genital schistosomiasis using cervicovaginal lavage and vaginal self-swab samples.
BACKGROUND
Female genital schistosomiasis (FGS) is a neglected and disabling gynecological disease that can result from infection with the parasitic trematode Schistosoma haematobium. Accurate diagnosis of FGS is crucial for effective case management, surveillance and control. However, current methods for diagnosis and morbidity assessment can be inaccessible to those at need, labour intensive, costly and unreliable. Molecular techniques such as PCR can be used to reliably diagnose FGS via the detection of Schistosoma DNA using cervicovaginal lavage (CVL) samples as well as lesser-invasive vaginal self-swab (VSS) and cervical self-swab samples. PCR is, however, currently unsuited for use in most endemic settings. As such, in this study, we assessed the use of a rapid and portable S. haematobium recombinase polymerase amplification (Sh-RPA) isothermal molecular diagnostic assay, coupled with simplified sample preparation methodologies, to detect S. haematobium DNA using CVL and VSS samples provided by patients in Zambia.
METHODOLOGY/PRINCIPAL FINDINGS
VSS and CVL samples were screened for FGS using a previously developed Sh-RPA assay. DNA was isolated from VSS and CVL samples using the QIAamp Mini kit (n = 603 and 527, respectively). DNA was also isolated from CVL samples using two rapid and portable DNA extraction methods: 1) the SpeedXtract Nucleic Acid Kit (n = 223) and 2) the Extracta DNA Tissue Prep Kit (n = 136). Diagnostic performance of the Sh-RPA using VSS DNA extacts (QIAamp Mini kit) as well as CVL DNA extracts (QIAamp Mini kit, SpeedXtract Nucleic Acid Kit and Extracta DNA Tissue Prep Kit) was then compared to a real-time PCR reference test. Results suggest that optimal performance may be achieved when the Sh-RPA is used with PuVSS samples (sensitivity 93.3%; specificity 96.6%), however no comparisons between different DNA extraction methods using VSS samples could be carried out within this study. When using CVL samples, sensitivity of the Sh-RPA ranged between 71.4 and 85.7 across all three DNA extraction methods when compared to real-time PCR using CVL samples prepared using the QIAamp Mini kit. Interestingly, of these three DNA extraction methods, the rapid and portable SpeedXtract method had the greatest sensitivity and specificity (85.7% and 98.1%, respectively). Specificity of the Sh-RPA was >91% across all comparisons.
CONCLUSIONS/SIGNIFICANCE
These results supplement previous findings, highlighting that the use of genital self-swab sampling for diagnosing FGS should be explored further whilst also demonstrating that rapid and portable DNA isolation methods can be used to detect S. haematobium DNA within clinical samples using RPA. Although further development and assessment is needed, it was concluded that the Sh-RPA, coupled with simplified sample preparation, shows excellent promise as a rapid and sensitive diagnostic tool capable of diagnosing FGS at the point-of-care in resource-poor schistosomiasis-endemic settings.
Topics: Animals; DNA; Female; Genitalia, Female; Humans; Nucleic Acid Amplification Techniques; Real-Time Polymerase Chain Reaction; Recombinases; Schistosoma haematobium; Schistosomiasis; Sensitivity and Specificity; Therapeutic Irrigation
PubMed: 35286336
DOI: 10.1371/journal.pntd.0010276 -
Malawi Medical Journal : the Journal of... Mar 2017The prevalence of infection has been shown to be about 23.7% among children living in the lakeshore areas of Malawi, with reinfection rates of about 30% to 40%. This...
BACKGROUND
The prevalence of infection has been shown to be about 23.7% among children living in the lakeshore areas of Malawi, with reinfection rates of about 30% to 40%. This study aimed to determine the current prevalence and distribution of infection in school children along the southwestern shores of Lake Malawi and examine the control interventions present in the area.
METHODS
This prospective cross-sectional study was conducted in primary schools. School children were enrolled, demographic data were collected, and urine samples were submitted for analysis on macrohaematuria, microhaematuria, and eggs. A questionnaire was administered to 3 health facilities on diagnosis and treatment of schistosomiasis, as well as the control interventions against it.
RESULTS
Four hundred children (174 males and 226 females) were enrolled from 7 primary schools. Mean participant age was 9.57 years (range 7 to 12 years). Fifty children (12.5%) had eggs detected in their urine, with the mean egg count being 15/10 mL. The highest infection intensity category (≥ 50 eggs/10mL) was seen in 10 children (2.5%). Prevalence varied significantly between the schools, with rates ranging from 0% to 20%. Schools with higher prevalence rates were located farther away from the nearest public hospital that provides treatment free of charge. Prevalence correlated with previous history of mass chemotherapy in schools. Mass chemotherapy, health education, and improved water supply and sanitation were some of the interventions that contributed to lower prevalence rates in some areas.
CONCLUSIONS
Schistosomiasis prevalence around southwestern Lake Malawi was lower than previously reported, owing to control interventions focusing on health education, improved water supply, sanitation, and mass chemotherapy. Consistent and uniform interventions can reduce prevalence further and sustain control. As prevalence falls, diagnostics can identify high transmission areas, monitor disease trends, and guide evidence-based control strategies.
Topics: Animals; Child; Cross-Sectional Studies; Female; Humans; Lakes; Malawi; Male; Prevalence; Prospective Studies; Schistosoma haematobium; Schistosomiasis haematobia; School Health Services; Schools; Surveys and Questionnaires; Urine
PubMed: 28567191
DOI: 10.4314/mmj.v29i1.4 -
Parasites & Vectors Aug 2023Although schistosomiasis is a public health issue in Mali, little is known about the parasite genetic profile. The purpose of this study was to analyze the genetic...
BACKGROUND
Although schistosomiasis is a public health issue in Mali, little is known about the parasite genetic profile. The purpose of this study was to analyze the genetic profile of the schistosomes of Schistosoma haematobium group in school-aged children in various sites in Mali.
METHODS
Urine samples were collected from 7 to 21 November 2021 and subjected to a filtration method for the presence S. haematobium eggs. The study took place in two schistosomiasis endemic villages (Fangouné Bamanan and Diakalèl), qualified as hotspots according to the World Health Organization (WHO) definition. Molecular genotyping on both Cox1 and ITS2/18S was used for eggs' taxonomic assignation.
RESULTS
A total of 970 miracidia were individually collected from 63 school-aged children and stored on Whatman FTA cards for molecular analysis. After genotyping 42.0% (353/840) and 58.0% (487/840) of miracidia revealed Schistosoma bovis and S. haematobium Cox1 profiles, respectively; 95.7 (885/925) and 4.3% (40/925) revealed S. haematobium and S. haematobium/S. curassoni profiles for ITS/18S genes, respectively. There was a significant difference in the Cox1 and ITS2/18S profile distribution according to the village (P < 0.0001). Overall, 45.6% (360/789) were hybrids, of which 72.0% (322/447) were from Diakalèl. Three hybrids' profiles (Sb/Sc_ShxSc with 2.3%; Sb/Sc_ShxSh with 40.5%; Sh_ShxSc with 2.8%) and one pure profile (Sh_ShxSh with 54.4%) were identified.
CONCLUSION
Our findings show, for the first time to our knowledge, high prevalence of hybrid schistosomes in Mali. More studies are needed on population genetics of schistosomes at the human and animal interface to evaluate the parasite's gene flow and its consequences on epidemiology of the disease as well as the transmission to humans.
Topics: Child; Animals; Humans; Schistosoma haematobium; Parasites; Disease Hotspot; Genetic Profile; Schistosoma; Schistosomiasis; Schistosomiasis haematobia
PubMed: 37542265
DOI: 10.1186/s13071-023-05860-8 -
Memorias Do Instituto Oswaldo Cruz 2020BACKGROUND Key genes control the infectivity of the Schistosoma haematobium causing schistosomiasis. A method for understanding the regulation of these genes might help...
BACKGROUND Key genes control the infectivity of the Schistosoma haematobium causing schistosomiasis. A method for understanding the regulation of these genes might help in developing new disease strategies to control schistosomiasis, such as the silencing mediated by microRNAs (miRNAs). The miRNAs have been studied in schistosome species and they play important roles in the post-transcriptional regulation of genes, and in parasite-host interactions. However, genome-wide identification and characterisation of novel miRNAs and their pathway genes and their gene expression have not been explored deeply in the genome and transcriptome of S. haematobium. OBJECTIVES Identify and characterise mature and precursor miRNAs and their pathway genes in the S. haematobium genome. METHODS Computational prediction and characterisation of miRNAs and genes involved in miRNA pathway from S. haematobium genome on SchistoDB. Conserved domain analysis was performed using PFAM and CDD databases. A robust algorithm was applied to identify mature miRNAs and their precursors. The characterisation of the precursor miRNAs was performed using RNAfold, RNAalifold and Perl scripts. FINDINGS We identified and characterised 14 putative proteins involved in miRNA pathway including ARGONAUTE and DICER in S. haematobium. Besides that, 149 mature miRNAs and 131 precursor miRNAs were identified in the genome including novel miRNAs. MAIN CONCLUSIONS miRNA pathway occurs in the S. haematobium, including endogenous miRNAs and miRNA pathway components, suggesting a role of this type of non-coding RNAs in gene regulation in the parasite. The results found in this work will open up a new avenue for studying miRNAs in the S. haematobium biology in helping to understand the mechanism of gene silencing in the human parasite Schistosome.
Topics: Animals; Computational Biology; Gene Expression Regulation; Humans; MicroRNAs; Schistosoma haematobium; Schistosomiasis; Sequence Analysis, RNA; Transcriptome
PubMed: 32401998
DOI: 10.1590/0074-02760190378 -
BMC Public Health Jan 2018To achieve a world free of schistosomiasis, the objective is to scale up control and elimination efforts in all endemic countries. Where interruption of transmission is... (Randomized Controlled Trial)
Randomized Controlled Trial
Interrupting seasonal transmission of Schistosoma haematobium and control of soil-transmitted helminthiasis in northern and central Côte d'Ivoire: a SCORE study protocol.
BACKGROUND
To achieve a world free of schistosomiasis, the objective is to scale up control and elimination efforts in all endemic countries. Where interruption of transmission is considered feasible, countries are encouraged to implement a comprehensive intervention package, including preventive chemotherapy, information, education and communication (IEC), water, sanitation and hygiene (WASH), and snail control. In northern and central Côte d'Ivoire, transmission of Schistosoma haematobium is seasonal and elimination might be achieved. In a cluster-randomised trial, we will assess different treatment schemes to interrupt S. haematobium transmission and control soil-transmitted helminthiasis over a 3-year period. We will compare the impact of (i) arm A: annual mass drug administration (MDA) with praziquantel and albendazole before the peak schistosomiasis transmission season; (ii) arm B: annual MDA after the peak schistosomiasis transmission season; (iii) arm C: two yearly treatments before and after peak schistosomiasis transmission; and (iv) arm D: annual MDA before peak schistosomiasis transmission, coupled with chemical snail control using niclosamide.
METHODS/DESIGN
The prevalence and intensity of S. haematobium and soil-transmitted helminth infections will be assessed using urine filtration and Kato-Katz thick smears, respectively, in six administrative regions in northern and central parts of Côte d'Ivoire. Once a year, urine and stool samples will be collected and examined from 50 children aged 5-8 years, 100 children aged 9-12 years and 50 adults aged 20-55 years in each of 60 selected villages. Changes in S. haematobium and soil-transmitted helminth prevalence and intensity will be assessed between years and stratified by intervention arm. In the 15 villages randomly assigned to intervention arm D, intermediate host snails will be collected three times per year, before niclosamide is applied to the selected freshwater bodies. The snail abundance and infection rates over time will allow drawing inference on the force of transmission.
DISCUSSION
This cluster-randomised intervention trial will elucidate whether in an area with seasonal transmission, the four different treatment schemes can interrupt S. haematobium transmission and control soil-transmitted helminthiasis. Lessons learned will help to guide schistosomiasis control and elimination programmes elsewhere in Africa.
TRIAL REGISTRATION
ISRCTN ISRCTN10926858 . Registered 21 December 2016. Retrospectively registered.
Topics: Adult; Albendazole; Animals; Anthelmintics; Child; Child, Preschool; Cluster Analysis; Cote d'Ivoire; Disease Eradication; Female; Humans; Male; Middle Aged; Niclosamide; Praziquantel; Prevalence; Schistosoma haematobium; Schistosomiasis; Seasons; Soil; Treatment Outcome; Young Adult
PubMed: 29378542
DOI: 10.1186/s12889-018-5044-2 -
BioMed Research International 2021World Health Organization (WHO) has approved only one treatment for schistosomiasis, praziquantel (PZQ), but some poor efficacy was noticed in patients during the early...
World Health Organization (WHO) has approved only one treatment for schistosomiasis, praziquantel (PZQ), but some poor efficacy was noticed in patients during the early stage of infection. Therefore, researchers have intensified their efforts to research new alternative medicines to treat schistosomiasis. In the present study, as well as studies have been accomplished to evaluate the effect of , , and extracts in a different concentration 500, 250, 125, 62.5, and 31.25 g/ml on golden hamster infected by Egyptian strains of schistosome (). , the adult worms and schistosomula of were investigated in RPMI-1640 medium for 48 hrs. The results showed that the concentration 500, 250, and 125 g/ml of , and caused dead of 100% of Egyptian strains of adult worm and schistosomula of within 6 to 12 hrs of incubation. On the other hand, the extract of at concentrations 500, 250, and 125 g/ml showed death 100% parasites after 12 to 24 hrs of incubation. Inclusion, , and showed effectiveness against Egyptian strains (), a slight decrease in was observed. Therefore, these medical plant extracts may be used as a safe and effective treatment for schistosomiasis.
Topics: Animals; Antiprotozoal Agents; Chlorocebus aethiops; In Vitro Techniques; Male; Mesocricetus; Microscopy, Electron, Scanning; Origanum; Plant Extracts; Praziquantel; Salvia; Schistosoma haematobium; Schistosomiasis haematobia; Treatment Outcome; Vero Cells; Ziziphus
PubMed: 34235218
DOI: 10.1155/2021/5545331 -
PLoS Neglected Tropical Diseases Mar 2020Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may...
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 likely to optimise its performance. We anticipate that environmental DNA-based approaches will help to inform epidemiological studies and contribute to efforts to control and eliminate schistosomiasis in endemic areas.
Topics: Animals; DNA, Environmental; DNA, Helminth; Environmental Monitoring; Fresh Water; Genes, Helminth; Nucleic Acid Amplification Techniques; Phylogeny; Real-Time Polymerase Chain Reaction; Schistosoma; Schistosoma haematobium; Schistosoma japonicum; Schistosoma mansoni; Schistosomiasis; Schistosomiasis mansoni; Snails; Species Specificity; Tanzania
PubMed: 32203507
DOI: 10.1371/journal.pntd.0008129 -
Clinical Microbiology Reviews Jan 2008Schistosomiasis, caused by trematode blood flukes of the genus Schistosoma, is recognized as the most important human helminth infection in terms of morbidity and... (Review)
Review
Schistosomiasis, caused by trematode blood flukes of the genus Schistosoma, is recognized as the most important human helminth infection in terms of morbidity and mortality. Infection follows direct contact with freshwater harboring free-swimming larval (cercaria) forms of the parasite. Despite the existence of the highly effective antischistosome drug praziquantel (PZQ), schistosomiasis is spreading into new areas, and although it is the cornerstone of current control programs, PZQ chemotherapy does have limitations. In particular, mass treatment does not prevent reinfection. Furthermore, there is increasing concern about the development of parasite resistance to PZQ. Consequently, vaccine strategies represent an essential component for the future control of schistosomiasis as an adjunct to chemotherapy. An improved understanding of the immune response to schistosome infection, both in animal models and in humans, suggests that development of a vaccine may be possible. This review considers aspects of antischistosome protective immunity that are important in the context of vaccine development. The current status in the development of vaccines against the African (Schistosoma mansoni and S. haematobium) and Asian (S. japonicum) schistosomes is then discussed, as are new approaches that may improve the efficacy of available vaccines and aid in the identification of new targets for immune attack.
Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Humans; Schistosoma; Schistosoma haematobium; Schistosoma japonicum; Schistosomiasis; Schistosomiasis mansoni; Vaccination; Vaccines; Vaccines, DNA; Vaccines, Synthetic
PubMed: 18202444
DOI: 10.1128/CMR.00046-07 -
Trends in Parasitology Jul 2014Urogenital schistosomiasis, infection with Schistosoma haematobium, is linked to increased risk for the development of bladder cancer, but the importance of various... (Review)
Review
Urogenital schistosomiasis, infection with Schistosoma haematobium, is linked to increased risk for the development of bladder cancer, but the importance of various mechanisms responsible for this association remains unclear, in part, owing to lack of sufficient and appropriate animal models. New advances in the study of this parasite, bladder regenerative processes, and human schistosomal bladder cancers may shed new light on the complex biological processes that connect S. haematobium infection to bladder carcinogenesis.
Topics: Animals; Humans; Inflammation; Intestines; Research; Schistosoma haematobium; Schistosomiasis haematobia; Urinary Bladder; Urinary Bladder Neoplasms
PubMed: 24913983
DOI: 10.1016/j.pt.2014.05.004