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PLoS Neglected Tropical Diseases Dec 2014Access to "safe" water and "adequate" sanitation are emphasized as important measures for schistosomiasis control. Indeed, the schistosomes' lifecycles suggest that... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Access to "safe" water and "adequate" sanitation are emphasized as important measures for schistosomiasis control. Indeed, the schistosomes' lifecycles suggest that their transmission may be reduced through safe water and adequate sanitation. However, the evidence has not previously been compiled in a systematic review.
METHODOLOGY
We carried out a systematic review and meta-analysis of studies reporting schistosome infection rates in people who do or do not have access to safe water and adequate sanitation. PubMed, Web of Science, Embase, and the Cochrane Library were searched from inception to 31 December 2013, without restrictions on year of publication or language. Studies' titles and abstracts were screened by two independent assessors. Papers deemed of interest were read in full and appropriate studies included in the meta-analysis. Publication bias was assessed through the visual inspection of funnel plots and through Egger's test. Heterogeneity of datasets within the meta-analysis was quantified using Higgins' I2.
PRINCIPAL FINDINGS
Safe water supplies were associated with significantly lower odds of schistosomiasis (odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.47-0.61). Adequate sanitation was associated with lower odds of Schistosoma mansoni, (OR = 0.59, 95% CI: 0.47-0.73) and Schistosoma haematobium (OR = 0.69, 95% CI: 0.57-0.84). Included studies were mainly cross-sectional and quality was largely poor.
CONCLUSIONS/SIGNIFICANCE
Our systematic review and meta-analysis suggests that increasing access to safe water and adequate sanitation are important measures to reduce the odds of schistosome infection. However, most of the studies were observational and quality was poor. Hence, there is a pressing need for adequately powered cluster randomized trials comparing schistosome infection risk with access to safe water and adequate sanitation, more studies which rigorously define water and sanitation, and new research on the relationships between water, sanitation, hygiene, human behavior, and schistosome transmission.
Topics: Cross-Sectional Studies; Humans; Sanitation; Schistosomiasis; Water Quality; Water Supply
PubMed: 25474705
DOI: 10.1371/journal.pntd.0003296 -
PLoS Neglected Tropical Diseases Mar 2021We were tasked by the World Health Organization (WHO) to address the following question: What techniques should be used to diagnose Schistosoma infections in snails and...
BACKGROUND
We were tasked by the World Health Organization (WHO) to address the following question: What techniques should be used to diagnose Schistosoma infections in snails and in the water in potential transmission sites? Our goal was to review and evaluate the available literature and provide recommendations and insights for the development of WHO's Guidelines Development Group for schistosomiasis control and elimination.
METHODOLOGY
We searched several databases using strings of search terms, searched bibliographies of pertinent papers, and contacted investigators who have made contributions to this field. Our search covered from 1970 to Sept 2020. All papers were considered in a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, and retained papers were grouped by technique and subjected to our GRADE (Grading of Recommendations, Assessment, Development and Evaluations) evidence assessment profile determined in consultation with WHO. We also considered issues of sensitivity, specificity, coverage, cost, robustness, support needs, schistosome species discrimination, and relevant detection limits.
PRINCIPAL FINDINGS
Our PRISMA process began with the perusal of 949 articles, of which 158 were retained for data extraction and evaluation. We identified 25 different techniques and for each applied a GRADE assessment considering limitations, inconsistency, imprecision, indirectness, and publication bias. We also provide advantages and disadvantages for each category of techniques.
CONCLUSIONS
Our GRADE analysis returned an assessment of moderate quality of evidence for environmental DNA (eDNA), qPCR and LAMP (Loop-mediated isothermal amplification). No single ideal diagnostic approach has yet been developed, but considerable recent progress has been made. We note a growing trend to use eDNA techniques to permit more efficient and replicable sampling. qPCR-based protocols for follow-up detection offer a versatile, mature, sensitive, and specific platform for diagnosis though centralized facilities will be required to favor standardization. Droplet digital PCR (ddPCR) can play a complementary role if inhibitors are a concern, or more sensitivity or quantification is needed. Snail collection, followed by shedding, is encouraged to provide specimens for sequence verifications of snails or schistosomes. LAMP or other isothermal detection techniques offer the prospect of less expensive and more distributed network of analysis but may face standardization and verification challenges related to actual sequences amplified. Ability to detect schistosome infections in snails or in the water is needed if control and elimination programs hope to succeed. Any diagnostic techniques used need to be regularly verified by the acquisition of DNA sequences to confirm that the detected targets are of the expected species. Further improvements may be necessary to identify the ideal schistosome or snail sequences to target for amplification. More field testing and standardization will be essential for long-term success.
Topics: Animals; DNA, Environmental; DNA, Helminth; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Real-Time Polymerase Chain Reaction; Schistosoma; Schistosomiasis; Snails; Water
PubMed: 33760814
DOI: 10.1371/journal.pntd.0009175 -
Tropical Diseases, Travel Medicine and... Feb 2021Schistosomiasis is a common helminthic infection in the tropics and subtropics, particularly in sub-Saharan African countries including Ethiopia. In these counties,... (Review)
Review
BACKGROUND
Schistosomiasis is a common helminthic infection in the tropics and subtropics, particularly in sub-Saharan African countries including Ethiopia. In these counties, Schistosoma mansoni infection is a significant public health problem due to the risk of reinfection and recurrent disease despite implementing several rounds preventive chemotherapy. This systematic review and meta-analysis aimed at assessing the pooled prevalence of schistosomiasis in Ethiopia.
METHODS
The PRISMA guidelines were followed to perform the systematic review and meta-analysis. Published studies from January 1999 to June 2020 were searched in Medline, PubMed, Google Scholar, EMBASE, HINARI, and Cochrane Library using key words including: "prevalence", "incidence", "schistosomiasis" "Bilharziasis", "Bilharzia", "S. mansoni ", "Ethiopia". Heterogeneity of included studies was assessed using Cochran's Q test and I test statistics while publication bias was assessed using Egger's test.
RESULTS
Ninety-four studies were included in the systematic review and meta-analysis. The pooled prevalence of S. mansoni in Ethiopia was 18.0% (95%CI: 14.0-23.0). The southern region of Ethiopia had a higher S. mansoni prevalence of 25.9% (995% CI, 14.9-41.1) than the national prevalence. The burden of S. mansoni infection was also higher than the national average in rural areas and among men with pooled prevalence of 20.2% (95% CI, 13.2-28.5) and 28.5% (95%CI, 22.7,35.1), respectively. The trend analysis showed that the prevalence of S. mansoni infection in Ethiopia decreased over the past 15 years, potentially because of the repeated preventive chemotherapy.
CONCLUSION
The review unveiled a moderate prevalence of S. mansoni infection in Ethiopia. Targeted treatment of at-risk population groups ad high burden areas coupled with implementation of integrated vector control strategies are critical to address the burden of Schistosomiasis.
PubMed: 33522949
DOI: 10.1186/s40794-020-00127-x -
Parasites & Vectors Dec 2014Schistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa.... (Review)
Review
INTRODUCTION
Schistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic review of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, we reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country and identified knowledge gaps and relevant areas for future research and research governance.
METHODS
We conducted computer-aided literature searches of Medline, SCOPUS and Google Scholar using the keywords: "schistosomiasis", "Bilharzia", "Bulinus" and "Biomphalaria" in combination with "Malawi". These searches were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed international scientific journals or other media. The recovered documents were reviewed for their year of publication, location of field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regarding parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission, and infection prevalence and intensities.
REVIEW
A total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published in international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the documents addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few documents addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi, intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studies in selected communities estimated prevalence rates of up to 94.9% for Schistosoma haematobium and up to 67.0% for Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.
CONCLUSION
Transmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in space and time. Many locations have not been covered by epidemiological investigations and, thus, information on the transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.
Topics: Humans; Malawi; Schistosomiasis
PubMed: 25490938
DOI: 10.1186/s13071-014-0570-y -
Pathogens and Global Health May 2019Schistosomiasis is a parasitic disease caused by helminths of the genus with two presentations; one intestinal and another urinary; which depend on the specie of . One... (Meta-Analysis)
Meta-Analysis
Schistosomiasis is a parasitic disease caused by helminths of the genus with two presentations; one intestinal and another urinary; which depend on the specie of . One of the species that can produce intestinal schistosomiasis is , and the specie that produces urinary schistosomiasis is . Infection can be aggravated by a deficient nutritional status, which negatively impacts the immune system and increases susceptibility to infection. The main objective of this meta-analysis is to determine if a relationship exists between multimicronutrient supplementation and the reduction of infestation with and in children and adolescents. A search was conducted through a scientific literature database, and articles that complied with the pre-established requirements were retrieved. The Review Manager (Rev Man) 5.3 computer program was used for data processing and analysis was carried out with the objective of testing whether the addition of micronutrient supplementation to treatment with broad-spectrum antiparasitic anthelmintic medication has an impact on schistosomiasis infection. Of the 257 initial articles retrieved, eight were included both quantitatively and qualitatively in the meta-analysis. Supplementation reduces infestation with 1.33 times more than placebo. In individuals infested with supplementation is 1.30 times more effective than placebo and for individuals infested with , supplementation is 1.62 times more effective than the placebo. The results show a clear relationship between supplementation and reduction of infestation. The supplementation with micronutrients decreases the presence of in children and adolescents.
Topics: Adolescent; Animals; Child; Child, Preschool; Female; Humans; Male; Micronutrients; Nutritional Status; Placebos; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis haematobia; Schistosomiasis mansoni
PubMed: 30983544
DOI: 10.1080/20477724.2019.1603902 -
PLoS Neglected Tropical Diseases Jan 2018By means of meta-analysis of information from all relevant epidemiologic studies, we examined the hypothesis that Schistosoma infection in school-aged children (SAC) is... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
By means of meta-analysis of information from all relevant epidemiologic studies, we examined the hypothesis that Schistosoma infection in school-aged children (SAC) is associated with educational loss and cognitive deficits.
METHODOLOGY/PRINCIPAL FINDINGS
This review was prospectively registered in the PROSPERO database (CRD42016040052). Medline, Biosis, and Web of Science were searched for studies published before August 2016 that evaluated associations between Schistosoma infection and cognitive or educational outcomes. Cognitive function was defined in four domains-learning, memory, reaction time, and innate intelligence. Educational outcome measures were defined as attendance and scholastic achievement. Risk of bias (ROB) was evaluated using the Newcastle-Ottawa quality assessment scale. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated to compare cognitive and educational measures for Schistosoma infected /not dewormed vs. uninfected/dewormed children. Sensitivity analyses by study design, ROB, and sequential exclusion of individual studies were implemented. Thirty studies from 14 countries, including 38,992 SAC between 5-19 years old, were identified. Compared to uninfected children and children dewormed with praziquantel, the presence of Schistosoma infection and/or non-dewormed status was associated with deficits in school attendance (SMD = -0.36, 95%CI: -0.60, -0.12), scholastic achievement (SMD = -0.58, 95%CI: -0.96, -0.20), learning (SMD = -0.39, 95%CI: -0.70, -0.09) and memory (SMD = -0.28, 95%CI: -0.52, -0.04) tests. By contrast, Schistosoma-infected/non-dewormed and uninfected/dewormed children were similar with respect to performance in tests of reaction time (SMD = -0.06, 95%CI: -0.42, 0.30) and intelligence (SMD = -0.25, 95%CI: -0.57, 0.06). Schistosoma infection-associated deficits in educational measures were robust among observational studies, but not among interventional studies. The significance of infection-associated deficits in scholastic achievement was sensitive to ROB. Schistosoma infection-related deficits in learning and memory tests were invariant by ROB and study design.
CONCLUSION/SIGNIFICANCE
Schistosoma infection/non-treatment was significantly associated with educational, learning, and memory deficits in SAC. Early treatment of children in Schistosoma-endemic regions could potentially mitigate these deficits.
TRIAL REGISTRATION
ClinicalTrials.gov CRD42016040052.
Topics: Adolescent; Animals; Anthelmintics; Child; Child, Preschool; Cognition; Cognitive Dysfunction; Humans; Intelligence; Learning Disabilities; Memory; Memory Disorders; Memory and Learning Tests; Praziquantel; Reaction Time; Schistosoma; Schistosomiasis
PubMed: 29329293
DOI: 10.1371/journal.pntd.0005524 -
Parasites & Vectors Mar 2015Schistosomiasis is a disease caused by infection with blood flukes of the genus Schistosoma. Transmission of, and exposure to, the parasite result from faecal or urinary... (Review)
Review
Schistosomiasis is a disease caused by infection with blood flukes of the genus Schistosoma. Transmission of, and exposure to, the parasite result from faecal or urinary contamination of freshwater containing intermediate host snails, and dermal contact with the same water. The World Health Assembly resolution 65.21 from May 2012 urges member states to eliminate schistosomiasis through preventive chemotherapy (i.e. periodic large-scale administration of the antischistosomal drug praziquantel to school-aged children and other high-risk groups), provision of water, sanitation and hygiene (WASH) and snail control. However, control measures focus almost exclusively on preventive chemotherapy, while only few studies made an attempt to determine the impact of upgraded access to safe water, adequate sanitation and good hygiene on schistosome transmission. We recently completed a systematic review and meta-analysis pertaining to WASH and schistosomiasis and found that people with safe water and adequate sanitation have significantly lower odds of a Schistosoma infection. Importantly though, the transmission of schistosomiasis is deeply entrenched in social-ecological systems, and hence is governed by setting-specific cultural and environmental factors that determine human behaviour and snail populations. Here, we provide a comprehensive review of the literature, which explores the transmission routes of schistosomes, particularly focussing on how these might be disrupted with WASH-related technologies and human behaviour. Additionally, future research directions in this area are highlighted.
Topics: Animals; Child; Fresh Water; Global Health; Humans; Hygiene; Male; Praziquantel; Sanitation; Schistosoma; Schistosomiasis; Snails; Water
PubMed: 25884172
DOI: 10.1186/s13071-015-0766-9 -
Diagnostics (Basel, Switzerland) Jun 2021Mobile health devices are emerging applications that could help deliver point-of-care (POC) diagnosis, particularly in settings with limited laboratory infrastructure,... (Review)
Review
Mobile health devices are emerging applications that could help deliver point-of-care (POC) diagnosis, particularly in settings with limited laboratory infrastructure, such as Sub-Saharan Africa (SSA). The advent of Severe acute respiratory syndrome coronavirus 2 has resulted in an increased deployment and use of mHealth-linked POC diagnostics in SSA. We performed a systematic review and meta-analysis to evaluate the accuracy of mobile-linked point-of-care diagnostics in SSA. Our systematic review and meta-analysis were guided by the Preferred Reporting Items requirements for Systematic Reviews and Meta-Analysis. We exhaustively searched PubMed, Science Direct, Google Scholar, MEDLINE, and CINAHL with full text via EBSCOhost databases, from mHealth inception to March 2021. The statistical analyses were conducted using OpenMeta-Analyst software. All 11 included studies were considered for the meta-analysis. The included studies focused on malaria infections, , , soil-transmitted helminths, and . The pooled summary of sensitivity and specificity estimates were moderate compared to those of the reference representing the gold standard. The overall pooled estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of mobile-linked POC diagnostic devices were as follows: 0.499 (95% CI: 0.458-0.541), 0.535 (95% CI: 0.401-0.663), 0.952 (95% CI: 0.60-1.324), 1.381 (95% CI: 0.391-4.879), and 0.944 (95% CI: 0.579-1.538), respectively. Evidence shows that the diagnostic accuracy of mobile-linked POC diagnostics in detecting infections in SSA is presently moderate. Future research is recommended to evaluate mHealth devices' diagnostic potential using devices with excellent sensitivities and specificities for diagnosing diseases in this setting.
PubMed: 34204848
DOI: 10.3390/diagnostics11061081 -
The Lancet. Microbe Apr 2024Accurate diagnosis is pivotal for implementing strategies for surveillance, control, and elimination of schistosomiasis. Despite their low sensitivity in low-endemicity... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Accurate diagnosis is pivotal for implementing strategies for surveillance, control, and elimination of schistosomiasis. Despite their low sensitivity in low-endemicity areas, microscopy-based urine filtration and the Kato-Katz technique are considered as reference diagnostic tests for Schistosoma haematobium and Schistosoma mansoni infections, respectively. We aimed to collate all available evidence on the accuracy of other proposed diagnostic techniques.
METHODS
In this systematic review and meta-analysis, we searched PubMed, Embase, the Cochrane Library, and LILACS for studies published from database inception to Dec 31, 2022, investigating the sensitivity and specificity of diagnostic tests for S haematobium and S mansoni infections against Kato-Katz thick smears or urine microscopy (reference tests) involving adults (aged ≥18 years), school-aged children (aged 7 to 18 years), or preschool-aged children (aged 1 month to 7 years). We extracted raw data on true positives, true negatives, false positives, and false negatives for the diagnostic tests and data on the number of participants, study authors, publication year, journal, study design, participants' age and sex, prevalence of Schistosoma infection, and treatment status. To account for imperfect reference tests, we used a hierarchical Bayesian latent class meta-analysis to model test accuracy.
FINDINGS
Overall, we included 121 studies, assessing 28 different diagnostic techniques. Most studies (103 [85%] of 121) were done in Africa, 14 (12%) in South America, one (1%) in Asia, and one (1%) in an unknown country. Compared with the reference test, Kato-Katz thick smears, circulating cathodic antigen urine cassette assay version 1 (CCA1, 36 test comparisons) had excellent sensitivity (95% [95% credible interval 88-99]) and reasonable specificity (74% [63-83]) for S mansoni. ELISA-based tests had a performance comparable to circulating cathodic antigen, but there were few available test comparisons. For S haematobium, proteinuria (42 test comparisons, sensitivity 73% [62-82]; specificity 94% [89-98]) and haematuria (75 test comparisons, sensitivity 85% [80-90]; specificity 96% [92-99]) reagent strips showed high specificity, with haematuria reagent strips having better sensitivity. Despite limited data, nucleic acid amplification tests (NAATs; eg, PCR or loop-mediated isothermal amplification [LAMP]) showed promising results with sensitivity estimates above 90%. We found an unclear risk of bias of about 70% in the use of the reference or index tests and of 50% in patient selection. All analyses showed substantial heterogeneity (I>80%).
INTERPRETATION
Although NAATs and immunological diagnostics show promise, the limited information available precludes drawing definitive conclusions. Additional research on diagnostic accuracy and cost-effectiveness is needed before the replacement of conventional tests can be considered.
FUNDING
WHO and Luxembourg Institute of Health.
Topics: Child; Child, Preschool; Adult; Animals; Humans; Adolescent; Schistosoma mansoni; Schistosoma haematobium; Hematuria; Reagent Strips; Microscopy; Bayes Theorem; Feces; Antigens, Helminth; Urinalysis; Schistosomiasis haematobia; Diagnostic Tests, Routine
PubMed: 38467130
DOI: 10.1016/S2666-5247(23)00377-4 -
Infectious Diseases of Poverty Apr 2018The speedy rate of change in the environmental and socio-economics factors may increase the incidence, prevalence and risk of schistosomiasis infections in Zambia.... (Review)
Review
BACKGROUND
The speedy rate of change in the environmental and socio-economics factors may increase the incidence, prevalence and risk of schistosomiasis infections in Zambia. However, available information does not provide a comprehensive understanding of the biogeography and distribution of the disease, ecology and population dynamics of intermediate host snails. The current study used an information-theoretical approach to understand the biogeography and prevalence schistosomiasis and identified knowledge gaps that would be useful to improve policy towards surveillance and eradication of intermediate hosts snails in Zambia.
METHODS
To summarise the existing knowledge and build on past and present experiences of schistosomiasis epidemiology for effective disease control in Zambia, a systematic search of literature for the period 2000-2017 was done on PubMed, Google Scholar and EBSCOhost. Using the key words: 'Schistosomiasis', 'Biomphalaria', 'Bulinus', 'Schistosoma mansoni', 'Schistosoma haematobium', and 'Zambia', in combination with Booleans terms 'AND' and 'OR', published reports/papers were obtained and reviewed independently for inclusion.
RESULTS
Thirteen papers published in English that fulfilled the inclusion criteria were selected for the final review. The papers suggest that the risk of infection has increased over the years and this has been attributed to environmental, socio-economic and demographic factors. Furthermore, schistosomiasis is endemic in many parts of the country with infection due to Schistosoma haematobium being more prevalent than that due to S. mansoni. This review also found that S. haematobium was linked to genital lesions, thus increasing risks of contracting other diseases such as HIV and cervical cancer.
CONCLUSIONS
For both S. haematobium and S. mansoni, environmental, socio-economic, and demographic factors were influential in the transmission and prevalence of the disease and highlight the need for detailed knowledge on ecological modelling and mapping the distribution of the disease and intermediate host snails for effective implementation of control strategies.
Topics: Animals; Humans; Prevalence; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis haematobia; Schistosomiasis mansoni; Socioeconomic Factors; Zambia
PubMed: 29706131
DOI: 10.1186/s40249-018-0424-5