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Tabo Z, Breuer L, Fabia C, Samuel G, Albrecht C. A machine learning approach for modeling the occurrence of the major intermediate hosts for schistosomiasis in East Africa. Sci Rep 2024; 14:4274. [PMID: 38383705 PMCID: PMC10881506 DOI: 10.1038/s41598-024-54699-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 02/15/2024] [Indexed: 02/23/2024] Open
Abstract
Schistosomiasis, a prevalent water-borne disease second only to malaria, significantly impacts impoverished rural communities, primarily in Sub-Saharan Africa where over 90% of the severely affected population resides. The disease, majorly caused by Schistosoma mansoni and S. haematobium parasites, relies on freshwater snails, specifically Biomphalaria and Bulinus species, as crucial intermediate host (IH) snails. Targeted snail control is advisable, however, there is still limited knowledge about the community structure of the two genera especially in East Africa. Utilizing a machine learning approach, we employed random forest to identify key features influencing the distribution of both IH snails in this region. Our results reveal geography and climate as primary factors for Biomphalaria, while Bulinus occurrence is additionally influenced by soil clay content and nitrogen concentration. Favorable climate conditions indicate a high prevalence of IHs in East Africa, while the intricate connection with geography might signify either dispersal limitations or environmental filtering. Predicted probabilities demonstrate non-linear patterns, with Bulinus being more likely to occur than Biomphalaria in the region. This study provides foundational framework insights for targeted schistosomiasis prevention and control strategies in the region, assisting health workers and policymakers in their efforts.
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Affiliation(s)
- Zadoki Tabo
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany.
- Institute for Landscape Ecology and Resource Management, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany.
| | - Lutz Breuer
- Institute for Landscape Ecology and Resource Management, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany
- Centre for International Development and Environmental Research (ZEU), Justus Liebig University Giessen, Senckenbergstrasse 3, 35390, Giessen, Germany
| | - Codalli Fabia
- Institute for Landscape Ecology and Resource Management, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany
| | - Gorata Samuel
- Institute for Landscape Ecology and Resource Management, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany
- Department of Environmental Science, Faculty of Science, University of Botswana, P/Bag UB00704, Gaborone, Botswana
| | - Christian Albrecht
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff-Ring 26 (iFZ), 35392, Giessen, Germany
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Gurarie D, Mondal A, Ndeffo-Mbah ML. Improved Assessment of Schistosoma Community Infection Through Data Resampling Method. Open Forum Infect Dis 2024; 11:ofad659. [PMID: 38328495 PMCID: PMC10847808 DOI: 10.1093/ofid/ofad659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 12/18/2023] [Indexed: 02/09/2024] Open
Abstract
Background The conventional diagnostic for Schistosoma mansoni infection is stool microscopy with the Kato-Katz (KK) technique to detect eggs. Its outcomes are highly variable on a day-to-day basis and may lead to biased estimates of community infection used to inform public health programs. Our goal is to develop a resampling method that leverages data from a large-scale randomized trial to accurately predict community infection. Methods We developed a resampling method that provides unbiased community estimates of prevalence, intensity and other statistics for S mansoni infection when a community survey is conducted using KK stool microscopy with a single sample per host. It leverages a large-scale data set, collected in the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) project, and allows linking single-stool specimen community screening to its putative multiday "true statistics." Results SCORE data analysis reveals the limited sensitivity of KK stool microscopy and systematic bias of single-day community testing versus multiday testing; for prevalence estimate, it can fall up to 50% below the true value. The proposed SCORE cluster method reduces systematic bias and brings the estimated prevalence values within 5%-10% of the true value. This holds for a broad swath of transmission settings, including SCORE communities, and other data sets. Conclusions Our SCORE cluster method can markedly improve the S mansoni prevalence estimate in settings using stool microscopy.
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Affiliation(s)
- David Gurarie
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, Ohio, USA
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Anirban Mondal
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, Ohio, USA
| | - Martial L Ndeffo-Mbah
- Department of Veterinary and Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
- Department of Epidemiology and Biostatistics, School of Public Health, Texas A&M University, College Station, Texas, USA
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Singer BJ, Coulibaly JT, Park HJ, Andrews JR, Bogoch II, Lo NC. Development of prediction models to identify hotspots of schistosomiasis in endemic regions to guide mass drug administration. Proc Natl Acad Sci U S A 2024; 121:e2315463120. [PMID: 38181058 PMCID: PMC10786280 DOI: 10.1073/pnas.2315463120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/13/2023] [Indexed: 01/07/2024] Open
Abstract
Schistosomiasis is a neglected tropical disease affecting over 150 million people. Hotspots of Schistosoma transmission-communities where infection prevalence does not decline adequately with mass drug administration-present a key challenge in eliminating schistosomiasis. Current approaches to identify hotspots require evaluation 2-5 y after a baseline survey and subsequent mass drug administration. Here, we develop statistical models to predict hotspots at baseline prior to treatment comparing three common hotspot definitions, using epidemiologic, survey-based, and remote sensing data. In a reanalysis of randomized trials in 589 communities in five endemic countries, a regression model predicts whether Schistosoma mansoni infection prevalence will exceed the WHO threshold of 10% in year 5 ("prevalence hotspot") with 86% sensitivity, 74% specificity, and 93% negative predictive value (NPV; assuming 30% hotspot prevalence), and a regression model for Schistosoma haematobium achieves 90% sensitivity, 90% specificity, and 96% NPV. A random forest model predicts whether S. mansoni moderate and heavy infection prevalence will exceed a public health goal of 1% in year 5 ("intensity hotspot") with 92% sensitivity, 79% specificity, and 96% NPV, and a boosted trees model for S. haematobium achieves 77% sensitivity, 95% specificity, and 91% NPV. Baseline prevalence is a top predictor in all models. Prediction is less accurate in countries not represented in training data and for a third hotspot definition based on relative prevalence reduction over time ("persistent hotspot"). These models may be a tool to prioritize high-risk communities for more frequent surveillance or intervention against schistosomiasis, but prediction of hotspots remains a challenge.
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Affiliation(s)
- Benjamin J. Singer
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA94304
| | - Jean T. Coulibaly
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, Basel, Allschwil4123Switzerland
- University of Basel, Basel4001, Switzerland
| | - Hailey J. Park
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA94304
| | - Jason R. Andrews
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA94304
| | - Isaac I. Bogoch
- Department of Medicine, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - Nathan C. Lo
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA94304
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Makaula P, Kayuni SA, Mamba KC, Bongololo G, Funsanani M, Juziwelo LT, Musaya J, Furu P. Mass drug administration campaigns: comparing two approaches for schistosomiasis and soil-transmitted helminths prevention and control in selected Southern Malawi districts. BMC Health Serv Res 2024; 24:11. [PMID: 38172854 PMCID: PMC10765822 DOI: 10.1186/s12913-023-10489-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Mass drug administration is one of the key interventions recommended by WHO to control certain NTDs. With most support from donors, health workers distribute antihelminthic drugs annually in Malawi. Mean community coverage of MDA from 2018 to 2020 was high at 87% for praziquantel and 82% for albendazole. However, once donor support diminishes sustaining these levels will be challenging. This study intended to compare the use of the community-directed intervention approach with the standard practice of using health workers in delivery of MDA campaigns. METHODS This was a controlled implementation study carried out in three districts, where four health centres and 16 villages in each district were selected and randomly assigned to intervention and control arms which implemented MDA campaigns using the CDI approach and the standard practice, respectively. Cross-sectional and mixed methods approach to data collection was used focusing on quantitative data for coverage and knowledge levels and qualitative data to assess perceptions of health providers and beneficiaries at baseline and follow-up assessments. Quantitative and qualitative data were analyzed using IBM SPSS software version 26 and NVivo 12 for Windows, respectively. RESULTS At follow-up, knowledge levels increased, majority of the respondents were more knowledgeable about what schistosomiasis was (41%-44%), its causes (41%-44%) and what STH were (48%-64%), while knowledge on intermediate host for schistosomiasis (19%-22%), its types (9%-13%) and what causes STH (15%-16%) were less known both in intervention and control arm communities. High coverage rates for praziquantel were registered in intervention (83%-89%) and control (86%-89%) communities, intervention (59%-79) and control (53%-86%) schools. Costs for implementation of the study indicated that the intervention arm used more resources than the control arm. Health workers and community members perceived the use of the CDI approach as a good initiative and more favorable over the standard practice. CONCLUSIONS The use of the CDI in delivery of MDA campaigns against schistosomiasis and STH appears feasible, retains high coverages and is acceptable in intervention communities. Despite the initial high costs incurred, embedding into community delivery platforms could be considered as a possible way forward addressing the sustainability concern when current donor support wanes. TRIAL REGISTRATION Pan-African Clinical Trials Registry PACTR202102477794401, date: 25/02/2021.
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Affiliation(s)
- Peter Makaula
- Research for Health Environment and Development, P.O. Box 345, Mangochi, Malawi.
- Malawi Liverpool Wellcome Research Programme, Private Bag 30096, Blantyre 3, Malawi.
| | - Sekeleghe Amos Kayuni
- Malawi Liverpool Wellcome Research Programme, Private Bag 30096, Blantyre 3, Malawi
- Medical Aid Society of Malawi (MASM) Medi Clinics Limited, Area 12 Medi Clinic, P.O. Box 31659, Lilongwe 3, Malawi
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | - Grace Bongololo
- Research for Health Environment and Development, P.O. Box 345, Mangochi, Malawi
| | - Mathias Funsanani
- Research for Health Environment and Development, P.O. Box 345, Mangochi, Malawi
| | - Lazarus Tito Juziwelo
- Ministry of Health, Community Health Sciences Unit, National Schistosomiasis and Soil-Transmitted Helminths Control Programme, Private Bag 65, Lilongwe, Malawi
| | - Janelisa Musaya
- Malawi Liverpool Wellcome Research Programme, Private Bag 30096, Blantyre 3, Malawi
- Department of Pathology, Kamuzu University of Health Sciences, Private Bag 360, Blantyre 3, Malawi
| | - Peter Furu
- Department of Public Health, Global Health Section, University of Copenhagen, 5 Øster Farimagsgade, 1014, Copenhagen K, Denmark.
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Mathewson JD, van der Spek L, Mazigo HD, Kabona G, de Vlas SJ, Nshala A, Rood EJJ. Enabling targeted mass drug administration for schistosomiasis in north-western Tanzania: Exploring the use of geostatistical modeling to inform planning at sub-district level. PLoS Negl Trop Dis 2024; 18:e0011896. [PMID: 38227610 PMCID: PMC10817176 DOI: 10.1371/journal.pntd.0011896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 01/26/2024] [Accepted: 01/02/2024] [Indexed: 01/18/2024] Open
Abstract
INTRODUCTION Schistosomiasis is a parasitic disease in Tanzania affecting over 50% of the population. Current control strategies involve mass drug administration (MDA) campaigns at the district level, which have led to problems of over- and under-treatment in different areas. WHO guidelines have called for more targeted MDA to circumvent these problems, however a scarcity of prevalence data inhibits decision makers from prioritizing sub-district areas for MDA. This study demonstrated how geostatistics can be used to inform planning for targeted MDA. METHODS Geostatistical sub-district (ward-level) prevalence estimates were generated through combining a zero-inflated poisson model and kriging approach (regression kriging). To make predictions, the model used prevalence survey data collected in 2021 of 17,400 school children in six regions of Tanzania, along with several open source ecological and socio-demographic variables with known associations with schistosomiasis. RESULTS The model results show that regression kriging can be used to effectively predict the ward level parasite prevalence of the two species of Schistosoma endemic to the study area. Kriging was found to further improve the regression model fit, with an adjusted R-squared value of 0.51 and 0.32 for intestinal and urogenital schistosomiasis, respectively. Targeted treatment based on model predictions would represent a shift in treatment away from 193 wards estimated to be over-treated to 149 wards that would have been omitted from the district level MDA. CONCLUSIONS Geostatistical models can help to support NTD program efficiency and reduce disease transmission by facilitating WHO recommended targeted MDA treatment through provision of prevalence estimates where data is scarce.
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Affiliation(s)
- Jake D. Mathewson
- Kit-Royal Tropical Institute, Epidemiology, Center for Applied Spatial Epidemiology (CASE), Amsterdam, The Netherlands
| | - Linda van der Spek
- Kit-Royal Tropical Institute, Epidemiology, Center for Applied Spatial Epidemiology (CASE), Amsterdam, The Netherlands
| | - Humphrey D. Mazigo
- School of Medicine, Department of Medical Parasitology & Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - George Kabona
- Ministry of Health, National Neglected Tropical Diseases Control Programme, Dodoma, Tanzania
| | - Sake J. de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | - Ente J. J. Rood
- Kit-Royal Tropical Institute, Epidemiology, Center for Applied Spatial Epidemiology (CASE), Amsterdam, The Netherlands
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Lim RM, Arme TM, Pedersen AB, Webster JP, Lamberton PHL. Defining schistosomiasis hotspots based on literature and shareholder interviews. Trends Parasitol 2023; 39:1032-1049. [PMID: 37806786 DOI: 10.1016/j.pt.2023.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/11/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023]
Abstract
The World Health Organization (WHO) recently proposed a new operational definition which designates communities with ≥10% prevalence of Schistosoma spp. infection as a persistent hotspot, when, after at least two rounds of high-coverage annual preventive chemotherapy, there is a lack of appropriate reduction. However, inconsistencies and challenges from both biological and operational perspectives remain, making the prescriptive use of this definition difficult. Here, we present a comprehensive analysis of the use of the term 'hotspot' across schistosomiasis research over time, including both literature searches and opinions from a range of stakeholders, to assess the utility and generalisability of the new WHO definition of a persistent hotspot. Importantly, we propose an updated definition based on our analyses.
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Affiliation(s)
- Rivka M Lim
- Institute of Evolution and Ecology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK.
| | - Thomas M Arme
- School of Biodiversity, One Health and Veterinary Medicine, Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Amy B Pedersen
- Institute of Evolution and Ecology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Joanne P Webster
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield, Herts, UK
| | - Poppy H L Lamberton
- School of Biodiversity, One Health and Veterinary Medicine, Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
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Nyangiri OA, Mulindwa J, Namulondo J, Kitibwa A, Nassuuna J, Elliott A, Kimuda MP, Boobo A, Nerima B, Adriko M, Dunton NJ, Madhan GK, Kristiansen M, Casacuberta-Partal M, Noyes H, Matovu E. Variants of IL6, IL10, FCN2, RNASE3, IL12B and IL17B loci are associated with Schistosoma mansoni worm burden in the Albert Nile region of Uganda. PLoS Negl Trop Dis 2023; 17:e0011796. [PMID: 38033168 PMCID: PMC10715658 DOI: 10.1371/journal.pntd.0011796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 12/12/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
BACKGROUND Individuals genetically susceptible to high schistosomiasis worm burden may contribute disproportionately to transmission and could be prioritized for control. Identifying genes involved may guide development of therapy. METHODOLOGY/PRINCIPAL FINDINGS A cohort of 606 children aged 10-15 years were recruited in the Albert Nile region of Uganda and assessed for Schistosoma mansoni worm burden using the Up-Converting Particle Lateral Flow (UCP-LF) test detecting circulating anodic antigen (CAA), point-of-care Circulating Cathodic Antigen (POC-CCA) and Kato-Katz tests. Whole genome genotyping was conducted on 326 children comprising the top and bottom 25% of worm burden. Linear models were fitted to identify variants associated with worm burden in preselected candidate genes. Expression quantitative trait locus (eQTL) analysis was conducted for candidate genes with UCP-LF worm burden included as a covariate. Single Nucleotide Polymorphism loci associated with UCP-LF CAA included IL6 rs2066992 (OR = 0.43, p = 0.0006) and rs7793163 (OR = 2.0, p = 0.0007); IL21 SNP kgp513476 (OR 1.79, p = 0.0025) and IL17B SNP kgp708159 (OR = 0.35, p = 0.0028). A haplotype in the IL10 locus was associated with lower worm burden (OR = 0.53, p = 0.015) and overlapped SNPs rs1800896, rs1800871 and rs1800872. Significant haplotypes (p<0.05, overlapping significant SNP) associated with worm burden were observed in IL6 and the Th17 pathway IL12B and IL17B genes. There were significant eQTL in the IL6, IL5, IL21, IL25 and IFNG regions. CONCLUSIONS Variants associated with S. mansoni worm burden were in IL6, FCN2, RNASE3, IL10, IL12B and IL17B gene loci. However only eQTL associations remained significant after Bonferroni correction. In summary, immune balance, pathogen recognition and Th17 pathways may play a role in modulating Schistosoma worm burden. Individuals carrying risk variants may be targeted first in allocation of control efforts to reduce the burden of schistosomiasis in the community.
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Affiliation(s)
- Oscar Asanya Nyangiri
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Julius Mulindwa
- Department of Biochemistry and Sports Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Joyce Namulondo
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Anna Kitibwa
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Jacent Nassuuna
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Alison Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Magambo Phillip Kimuda
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Alex Boobo
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Barbara Nerima
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Moses Adriko
- Vector Borne & NTD Control Division, Ministry of Health, Uganda
| | - Nathan J. Dunton
- UCL Genomics core facility, University College London, London, United Kingdom
| | | | - Mark Kristiansen
- UCL Genomics core facility, University College London, London, United Kingdom
| | | | - Harry Noyes
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Enock Matovu
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
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Dorkenoo AM, Phillips AE, Klein L, Lack F, Ataba E, Yakpa K, Tagba AE, Assoti BE, Sossou E, Tchalim M, Datagni G, Seim A, Milord MD, Kassankogno Y. Progress from morbidity control to elimination as a public health problem of schistosomiasis and the status of soil-transmitted helminth infection in Togo: a second impact assessment after ten rounds of mass drug administration. Parasit Vectors 2023; 16:314. [PMID: 37667301 PMCID: PMC10478252 DOI: 10.1186/s13071-023-05882-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/14/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Due to the burden of schistosomiasis (SCH) and soil-transmitted helminths (STH), Togo Ministry of Health launched a program for Preventive Chemotherapy Neglected Tropical Diseases (PC-NTDs) in 2009, initiating integrated mass drug administration (MDA) the following year for the three PC-NTDs: SCH, STH and onchocerciasis. Significant reduction of infection across the country was noted in 2015 during the first impact assessment, following 5 years of high-coverage MDA implemented at the sub-district level for SCH and district level for STH. After another 5 years of effective MDA, a second survey was conducted in 2021 to re-evaluate the situation of SCH and STH. METHODS A cross-section of school-aged children was taken across ten districts of Togo. A total of 302 schools in 92 sub-districts were sampled, with 24 school-aged children per school resulting in 7248 children surveyed. Urine samples were tested by haemastix® for Schistosoma haematobium, with urine filtration for the presence of eggs conducted on haematuria-positive samples. Stool samples were collected in a subset of 34 sub-districts in seven out of the ten surveyed districts, where STH and Schistosoma mansoni endemicity was high during the 2015 impact assessment. Duplicate (two) Kato-Katz analysis was performed for each stool sample. Sociodemographic and school-level water, sanitation and hygiene information was also collected. RESULTS Overall, SCH prevalence was 5.90% (95% CI: 5.4-6.5), with 5.09% (95% CI: 4.64-5.67) for S. haematobium and 2.56% (95% CI: 1.98-3.29) for S. mansoni. STH prevalence was 19.7% (95% CI: 18.2-21.4), with 19.6% (95% CI: 18.1-21.3) hookworm, 0.08% (95% CI: 2.2-5.8) Trichuris trichiura and 0.04% (95% CI: 0.01-0.33) Ascaris lumbricoides. Compared to baseline, a significant reduction in both SCH (22.2% to 5.90%) and STH (29.2% t0 19.7%) prevalence was observed. Children aged 5-9 years were less infected than older peers aged 10-14 years: 4.76% vs. 7.53% (P < 0.01) for SCH and 17.2% vs. 23.0% (P < 0.01) for STH. CONCLUSIONS After 10 years of high coverage integrated MDA, Togo has achieved low prevalence SCH infection through the sub-district MDA implementation with considerable infection heterogeneity within sub-districts. As STH infection has not reached a level where the infections are not a public health problem, the sub-district treatment strategy could also be adopted in addition to improvement of treatment coverage among preschool age children and hygiene and sanitation practices.
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Affiliation(s)
- Ameyo M Dorkenoo
- National Program for the Control of NTDs, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo.
- Department of Biological and Basic Sciences, Faculty of Health Sciences, University of Lomé, Lomé, Togo.
| | | | - Luke Klein
- Family Health International 360, Washington, DC, USA
| | - Fiali Lack
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Essoham Ataba
- Programme National de Lute Contre le Paludisme, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Kossi Yakpa
- Programme National de Lute Contre le Paludisme, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Atna-Edi Tagba
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Bozi-Esso Assoti
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Efoe Sossou
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Mawèké Tchalim
- National Program for the Control of NTDs, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | | | - Anders Seim
- Health and Development International, Fjellstrand, Norway
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Ismail HAHA, Cha S, Jin Y, Hong ST. Programmatic Implications for Schistosomiasis Elimination Based on Community-Based Survey in the Blue Nile, North Kordofan, and Sennar States, Sudan. Life (Basel) 2023; 13:life13041049. [PMID: 37109578 PMCID: PMC10143570 DOI: 10.3390/life13041049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
Schistosomiasis prevalence has remained high in some areas due to reinfection despite repeated mass drug administration interventions. We aimed to explore its risk factors in order to help to design adequate interventions in such high-transmission areas. A total of 6225 individuals residing in 60 villages in 8 districts of North Kordofan, Blue Nile, or Sennar States, Sudan participated in the community-based survey in March 2018. First, we investigated Schistosoma haematobium and Schistosoma mansoni prevalences among school-aged children and adults. Second, the associations between risk factors and schistosomiasis were explored. Those without any type of latrine in their households had higher odds of being infected with schistosomiasis than those with a latrine (odds ratio (OR) = 1.53; 95% confidence interval (CI) 1.20-1.94; p = 0.001), and the odds of being positive for schistosomiasis among people living in a household without an improved latrine were higher than for their counterparts with an improved latrine (OR = 1.63; CI 1.05-2.55; p = 0.03). Furthermore, people with households or outside compounds found to contain human faeces had higher odds of being infected with schistosomiasis than their counterparts (OR = 1.36, 95% CI 1.01-1.83, p = 0.04). Installing an improved latrine and eliminating open defecation should be highlighted in schistosomiasis elimination projects in high-transmission areas.
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Affiliation(s)
| | - Seungman Cha
- Department of Global Development and Entrepreneurship, Graduate School of Global Development and Entrepreneurship, Handong Global University, Pohang 37554, Republic of Korea
| | - Yan Jin
- Department of Microbiology, Dongguk University College of Medicine, Gyeongju 10326, Republic of Korea
| | - Sung-Tae Hong
- Department of Tropical Medicine and Parasitology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
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Lo NC, Bezerra FSM, Colley DG, Fleming FM, Homeida M, Kabatereine N, Kabole FM, King CH, Mafe MA, Midzi N, Mutapi F, Mwanga JR, Ramzy RMR, Satrija F, Stothard JR, Traoré MS, Webster JP, Utzinger J, Zhou XN, Danso-Appiah A, Eusebi P, Loker ES, Obonyo CO, Quansah R, Liang S, Vaillant M, Murad MH, Hagan P, Garba A. Review of 2022 WHO guidelines on the control and elimination of schistosomiasis. Lancet Infect Dis 2022; 22:e327-e335. [PMID: 35594896 DOI: 10.1016/s1473-3099(22)00221-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/13/2022] [Accepted: 03/21/2022] [Indexed: 01/13/2023]
Abstract
Schistosomiasis is a helminthiasis infecting approximately 250 million people worldwide. In 2001, the World Health Assembly (WHA) 54.19 resolution defined a new global strategy for control of schistosomiasis through preventive chemotherapy programmes. This resolution culminated in the 2006 WHO guidelines that recommended empirical treatment by mass drug administration with praziquantel, predominately to school-aged children in endemic settings at regular intervals. Since then, school-based and community-based preventive chemotherapy programmes have been scaled-up, reducing schistosomiasis-associated morbidity. Over the past 15 years, new scientific evidence-combined with a more ambitious goal of eliminating schistosomiasis and an increase in the global donated supply of praziquantel-has highlighted the need to update public health guidance worldwide. In February, 2022, WHO published new guidelines with six recommendations to update the global public health strategy against schistosomiasis, including expansion of preventive chemotherapy eligibility from the predominant group of school-aged children to all age groups (2 years and older), lowering the prevalence threshold for annual preventive chemotherapy, and increasing the frequency of treatment. This Review, written by the 2018-2022 Schistosomiasis Guidelines Development Group and its international partners, presents a summary of the new WHO guideline recommendations for schistosomiasis along with their historical context, supporting evidence, implications for public health implementation, and future research needs.
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Affiliation(s)
- Nathan C Lo
- Division of HIV, Infectious Diseases, and Global Medicine, University of California, San Francisco, CA, USA.
| | | | - Daniel G Colley
- Department of Microbiology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
| | | | - Mamoun Homeida
- Academy of Medical Sciences and Technology, Khartoum, Sudan
| | - Narcis Kabatereine
- Accelerating Resilient, Innovative, and Sustainable Elimination of NTDs, Vector Control Division, Kampala, Uganda
| | | | - Charles H King
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | | | - Nicholas Midzi
- National Institute of Health Research, Ministry of Health and Child Care, Harare, Zimbabwe
| | - Francisca Mutapi
- Institute of Immunology and Infection Research, Tackling Infections to Benefit Africa Partnership, University of Edinburgh, Edinburgh, UK
| | - Joseph R Mwanga
- Department of Epidemiology, Biostatistics and Behavioral Sciences, School of Public Health, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Reda M R Ramzy
- National Nutrition Institute, General Organization for Teaching Hospitals and Institutes, Cairo, Egypt
| | - Fadjar Satrija
- School of Veterinary Medicine and Biomedicine, IPB University, Bogor, Indonesia
| | - J Russell Stothard
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Joanne P Webster
- Department of Pathobiology and Population Science, Royal Veterinary College, University of London, London, UK
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland; University of Basel, Basel, Switzerland
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China; School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | | | - Paolo Eusebi
- Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Eric S Loker
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Charles O Obonyo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | | | - Song Liang
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA; Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Michel Vaillant
- Competence Centre for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
| | - M Hassan Murad
- Evidence-based Practice Center, Mayo Clinic, Rochester, NY, USA
| | - Paul Hagan
- Faculty of Health Sciences, University of Hull, Hull, UK
| | - Amadou Garba
- Department of Control of Neglected Tropical Diseases, WHO, Geneva, Switzerland
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11
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Grewelle RE, Perez-saez J, Tycko J, Namigai EKO, Rickards CG, De Leo GA. Modeling the efficacy of CRISPR gene drive for snail immunity on schistosomiasis control. PLoS Negl Trop Dis 2022; 16:e0010894. [DOI: 10.1371/journal.pntd.0010894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/10/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022] Open
Abstract
CRISPR gene drives could revolutionize the control of infectious diseases by accelerating the spread of engineered traits that limit parasite transmission in wild populations. Gene drive technology in mollusks has received little attention despite the role of freshwater snails as hosts of parasitic flukes causing 200 million annual cases of schistosomiasis. A successful drive in snails must overcome self-fertilization, a common feature of host snails which could prevents a drive’s spread. Here we developed a novel population genetic model accounting for snails’ mixed mating and population dynamics, susceptibility to parasite infection regulated by multiple alleles, fitness differences between genotypes, and a range of drive characteristics. We integrated this model with an epidemiological model of schistosomiasis transmission to show that a snail population modification drive targeting immunity to infection can be hindered by a variety of biological and ecological factors; yet under a range of conditions, disease reduction achieved by chemotherapy treatment of the human population can be maintained with a drive. Alone a drive modifying snail immunity could achieve significant disease reduction in humans several years after release. These results indicate that gene drives, in coordination with existing public health measures, may become a useful tool to reduce schistosomiasis burden in selected transmission settings with effective CRISPR construct design and evaluation of the genetic and ecological landscape.
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Morales-Vicente DA, Zhao L, Silveira GO, Tahira AC, Amaral MS, Collins JJ, Verjovski-Almeida S. Single-cell RNA-seq analyses show that long non-coding RNAs are conspicuously expressed in Schistosoma mansoni gamete and tegument progenitor cell populations. Front Genet 2022; 13:924877. [PMID: 36204320 PMCID: PMC9531161 DOI: 10.3389/fgene.2022.924877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/24/2022] [Indexed: 11/17/2022] Open
Abstract
Schistosoma mansoni is a flatworm that causes schistosomiasis, a neglected tropical disease that affects over 200 million people worldwide. New therapeutic targets are needed with only one drug available for treatment and no vaccine. Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with low or no protein-coding potential. In other organisms, they have been shown as involved with reproduction, stem cell maintenance and drug resistance, and they tend to exhibit tissue-specific expression patterns. S. mansoni expresses thousands of lncRNA genes; however, the cell type expression patterns of lncRNAs in the parasite remain uncharacterized. Here, we have re-analyzed publicly available single-cell RNA-sequencing (scRNA-seq) data obtained from adult S. mansoni to identify the lncRNAs signature of adult schistosome cell types. A total of 8023 lncRNAs (79% of all lncRNAs) were detected. Analyses of the lncRNAs expression profiles in the cells using statistically stringent criteria were performed to identify 74 lncRNA gene markers of cell clusters. Male gamete and tegument progenitor lineages clusters contained most of the cluster-specific lncRNA markers. We also identified lncRNA markers of specific neural clusters. Whole-mount in situ hybridization (WISH) and double fluorescence in situ hybridization were used to validate the cluster-specific expression of 13 out of 16 selected lncRNA genes (81%) in the male and female adult parasite tissues; for one of these 16 gene loci, probes for two different lncRNA isoforms were used, which showed differential isoform expression in testis and ovary. An atlas of the expression profiles across the cell clusters of all lncRNAs detected in our analysis is available as a public website resource (http://verjolab.usp.br:8081). The results presented here give strong support to a tissue-specific expression and to a regulated expression program of lncRNAs in S. mansoni. This will be the basis for further exploration of lncRNA genes as potential therapeutic targets.
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Affiliation(s)
- David A Morales-Vicente
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
- Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Lu Zhao
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Gilbert O Silveira
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
- Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Ana C Tahira
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
| | - Murilo S Amaral
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
| | - James J Collins
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Sergio Verjovski-Almeida
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
- Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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Summers S, Bhattacharyya T, Allan F, Stothard JR, Edielu A, Webster BL, Miles MA, Bustinduy AL. A review of the genetic determinants of praziquantel resistance in Schistosoma mansoni: Is praziquantel and intestinal schistosomiasis a perfect match? Front Trop Dis 2022. [DOI: 10.3389/fitd.2022.933097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Schistosomiasis is a neglected tropical disease (NTD) caused by parasitic trematodes belonging to the Schistosoma genus. The mainstay of schistosomiasis control is the delivery of a single dose of praziquantel (PZQ) through mass drug administration (MDA) programs. These programs have been successful in reducing the prevalence and intensity of infections. Due to the success of MDA programs, the disease has recently been targeted for elimination as a public health problem in some endemic settings. The new World Health Organization (WHO) treatment guidelines aim to provide equitable access to PZQ for individuals above two years old in targeted areas. The scale up of MDA programs may heighten the drug selection pressures on Schistosoma parasites, which could lead to the emergence of PZQ resistant schistosomes. The reliance on a single drug to treat a disease of this magnitude is worrying should drug resistance develop. Therefore, there is a need to detect and track resistant schistosomes to counteract the threat of drug resistance to the WHO 2030 NTD roadmap targets. Until recently, drug resistance studies have been hindered by the lack of molecular markers associated with PZQ resistance. This review discusses recent significant advances in understanding the molecular basis of PZQ action in S. mansoni and proposes additional genetic determinants associated with PZQ resistance. PZQ resistance will also be analyzed in the context of alternative factors that may decrease efficacy within endemic field settings, and the most recent treatment guidelines recommended by the WHO.
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14
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Zdesenko G, Mduluza T, Mutapi F. Pharmacogenetics of Praziquantel Metabolism: Evaluating the Cytochrome P450 Genes of Zimbabwean Patients During a Schistosomiasis Treatment. Front Genet 2022; 13:914372. [PMID: 35754834 PMCID: PMC9213834 DOI: 10.3389/fgene.2022.914372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Schistosomiasis is a parasitic disease infecting over 236 million people annually, with the majority affected residing on the African continent. Control of this disease is reliant on the drug praziquantel (PZQ), with treatment success dependent on an individual reaching PZQ concentrations lethal to schistosomes. Despite the complete reliance on PZQ to treat schistosomiasis in Africa, the characterization of the pharmacogenetics associated with PZQ metabolism in African populations has been sparse. We aimed to characterize genetic variation in the drug-metabolising cytochrome P450 enzymes (CYPs) and determine the association between each variant and the efficacy of PZQ treatment in Zimbabwean patients exposed to Schistosoma haematobium infection. Genomic DNA from blood samples of 114 case-control Zimbabweans infected with schistosomes were sequenced using the CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5 genes as targets. Bioinformatic tools were used to identify and predict functional effects of detected single nucleotide polymorphisms (SNPs). A random forest (RF) model was then used to assess SNPs most predictive of PZQ efficacy, with a misclassification rate of 29%. SNPs were detected across all six genes, with 70 SNPs identified and multiple functional changes to the CYP enzymes predicted. Only four SNPs were significantly associated with PZQ efficacy using χ2 tests, with rs951840747 (OR: 3.61, p = 0.01) in the CYP1A2 gene having the highest odds of an individual possessing this SNP clearing infection, and rs6976017 (OR: 2.19, p = 0.045) of CYP3A5 determined to be the most predictive of PZQ efficacy via the RF. Only the rs28371702 (CC) genotype (OR: 2.36, p = 0.024) of CYP2D6 was significantly associated with an unsuccessful PZQ treatment. This study adds to the genomic characterization of the diverse populations in Africa and identifies variants relevant to other pharmacogenetic studies crucial for the development and usage of drugs in these populations.
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Affiliation(s)
- Grace Zdesenko
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom.,Ashworth Laboratories, NIHR Global Health Research Unit Tackling Infections to Benefit Africa (TIBA), University of Edinburgh, Edinburgh, United Kingdom
| | - Takafira Mduluza
- Ashworth Laboratories, NIHR Global Health Research Unit Tackling Infections to Benefit Africa (TIBA), University of Edinburgh, Edinburgh, United Kingdom.,Department of Biochemistry, University of Zimbabwe, Harare, Zimbabwe
| | - Francisca Mutapi
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom.,Ashworth Laboratories, NIHR Global Health Research Unit Tackling Infections to Benefit Africa (TIBA), University of Edinburgh, Edinburgh, United Kingdom
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15
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Grover E, Paull S, Kechris K, Buchwald A, James K, Liu Y, Carlton EJ. Predictors of bovine Schistosoma japonicum infection in rural sichuan, china. Int J Parasitol 2022; 52:485-496. [DOI: 10.1016/j.ijpara.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 11/05/2022]
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Makaula P, Kayuni SA, Mamba KC, Bongololo G, Funsanani M, Musaya J, Juziwelo LT, Furu P. An assessment of implementation and effectiveness of mass drug administration for prevention and control of schistosomiasis and soil-transmitted helminths in selected southern Malawi districts. BMC Health Serv Res 2022; 22:517. [PMID: 35439991 PMCID: PMC9016207 DOI: 10.1186/s12913-022-07925-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 04/08/2022] [Indexed: 11/15/2022] Open
Abstract
Background Mass drug administration (MDA) is one of the key interventions recommended by WHO for prevention and control of neglected tropical diseases (NTD). In Malawi, MDA is widely carried out annually since 2009 for prevention and control of schistosomiasis and soil-transmitted helminths (STH). No study has been carried out to assess effectiveness of the MDA approach and to document perceptions of health providers and beneficiaries regarding use of MDA. This study was done to understand how well MDA is being implemented and to identify opportunities for improvement in MDA delivery in Malawi. Methods Designed as a cross-sectional and multi-methods research, the study was carried out in three southern Malawi districts of Chiradzulu, Mangochi and Zomba. In each district, four health centres and 16 villages were randomly selected to participate. A mixed-methods approach to data collection focusing on quantitative data for coverage and knowledge, attitudes and practices assessments; and qualitative data for assessing perceptions of health providers and beneficiaries regarding MDA was used. Quantitative data were processed and analyzed using IBM SPSS software version 26 while qualitative data were analysed using NVivo 12 for Windows. Results Knowledge levels about schistosomiasis and STH in the districts varied according to disease aspects asked about. Majority are more knowledgeable about what schistosomiasis is (78%) and whether STH are treatable with drugs (97%); with least knowledgeable about the organism that transmits schistosomiasis (18%), types of schistosomiasis (11%) and what causes STH (20%). In 2018 and 2019 the districts registered high coverage rates for praziquantel and albendazole using community-based MDA (73–100%) and using school-based MDA (75–91%). Both the health authorities and community members perceived the MDA approach as good because it brings treatment closer to people. Conclusion With the high MDA coverage obtained in communities and schools, the effectiveness of MDA in the target districts is satisfactory. There are, however, several challenges including disproportionate knowledge levels, which are hampering progress towards attainment of the 2030 global NTD goals. There is a need for promotion of community participation and partnerships as well as implementation of other recommended interventions for sustainable prevention and control of schistosomiasis and STH. Supplementary Information The online version contains supplementary material available at 10.1186/s12913-022-07925-3.
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Trienekens SCM, Faust CL, Besigye F, Pickering L, Tukahebwa EM, Seeley J, Lamberton PHL. Variation in water contact behaviour and risk of Schistosoma mansoni (re)infection among Ugandan school-aged children in an area with persistent high endemicity. Parasit Vectors 2022; 15:15. [PMID: 34991702 PMCID: PMC8734346 DOI: 10.1186/s13071-021-05121-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/11/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Annual mass drug administration with praziquantel has reduced schistosomiasis transmission in some highly endemic areas, but areas with persistent high endemicity have been identified across sub-Saharan Africa, including Uganda. In these areas many children are rapidly reinfected post treatment, while some children remain uninfected or have low-intensity infections. The aim of this mixed-methods study was to better understand variation in water contact locations, behaviours and infection risk in school-aged children within an area with persistent high endemicity to inform additional control efforts. METHODS Data were collected in Bugoto, Mayuge District, Uganda. Two risk groups were identified from a longitudinal cohort, and eight children with no/low-intensity infections and eight children with reinfections were recruited. Individual structured day-long observations with a focus on water contact were conducted over two periods in 2018. In all identified water contact sites, four snail surveys were conducted quarterly over 1 year. All observed Biomphalaria snails were collected, counted and monitored in the laboratory for Schistosoma mansoni cercarial shedding for 3 weeks. RESULTS Children came into contact with water for a range of purposes, either directly at the water sources or by coming into contact with water collected previously. Although some water contact practices were similar between the risk groups, only children with reinfection were observed fetching water for commercial purposes and swimming in water sources; this latter group of children also came into contact with water at a larger variety and number of sites compared to children with no/low-intensity infection. Households with children with no/low-intensity infections collected rainwater more often. Water contact was observed at 10 sites throughout the study, and a total of 9457 Biomphalaria snails were collected from these sites over four sampling periods. Four lake sites had a significantly higher Biomphalaria choanomphala abundance, and reinfected children came into contact with water at these sites more often than children with no/low-intensity infections. While only six snails shed cercariae, four were from sites only contacted by reinfected children. CONCLUSIONS Children with reinfection have more high-risk water contact behaviours and accessed water sites with higher B. choanomphala abundance, demonstrating that specific water contact behaviours interact with environmental features to explain variation in risk within areas with persistent high endemicity. Targeted behaviour change, vector control and safe water supplies could reduce reinfection in school-aged children in these settings.
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Affiliation(s)
- Suzan C. M. Trienekens
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Institute of Health & Wellbeing, College of Social Sciences, University of Glasgow, Glasgow, UK
| | - Christina L. Faust
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Fred Besigye
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Lucy Pickering
- Institute of Health & Wellbeing, College of Social Sciences, University of Glasgow, Glasgow, UK
| | | | - Janet Seeley
- Medical Research Council/Uganda Virus Research Institute, Entebbe, Uganda
- Department of Global Health and Development, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK
| | - Poppy H. L. Lamberton
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Lund AJ, Wade KJ, Nikolakis ZL, Ivey KN, Perry BW, Pike HNC, Paull SH, Liu Y, Castoe TA, Pollock DD, Carlton EJ. Integrating genomic and epidemiologic data to accelerate progress toward schistosomiasis elimination. eLife 2022; 11:79320. [PMID: 36040013 PMCID: PMC9427098 DOI: 10.7554/elife.79320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
The global community has adopted ambitious goals to eliminate schistosomiasis as a public health problem, and new tools are needed to achieve them. Mass drug administration programs, for example, have reduced the burden of schistosomiasis, but the identification of hotspots of persistent and reemergent transmission threaten progress toward elimination and underscore the need to couple treatment with interventions that reduce transmission. Recent advances in DNA sequencing technologies make whole-genome sequencing a valuable and increasingly feasible option for population-based studies of complex parasites such as schistosomes. Here, we focus on leveraging genomic data to tailor interventions to distinct social and ecological circumstances. We consider two priority questions that can be addressed by integrating epidemiological, ecological, and genomic information: (1) how often do non-human host species contribute to human schistosome infection? and (2) what is the importance of locally acquired versus imported infections in driving transmission at different stages of elimination? These questions address processes that can undermine control programs, especially those that rely heavily on treatment with praziquantel. Until recently, these questions were difficult to answer with sufficient precision to inform public health decision-making. We review the literature related to these questions and discuss how whole-genome approaches can identify the geographic and taxonomic sources of infection, and how such information can inform context-specific efforts that advance schistosomiasis control efforts and minimize the risk of reemergence.
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Affiliation(s)
- Andrea J Lund
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
| | - Kristen J Wade
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Zachary L Nikolakis
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Kathleen N Ivey
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Blair W Perry
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Hamish NC Pike
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Sara H Paull
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
| | - Yang Liu
- Sichuan Centers for Disease Control and PreventionChengduChina
| | - Todd A Castoe
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - David D Pollock
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Elizabeth J Carlton
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
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Lund AJ, Sokolow SH, Jones IJ, Wood CL, Ali S, Chamberlin A, Sy AB, Sam MM, Jouanard N, Schacht AM, Senghor S, Fall A, Ndione R, Riveau G, De Leo GA, López-Carr D. Exposure, hazard, and vulnerability all contribute to Schistosoma haematobium re-infection in northern Senegal. PLoS Negl Trop Dis 2021; 15:e0009806. [PMID: 34610025 PMCID: PMC8525765 DOI: 10.1371/journal.pntd.0009806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 10/19/2021] [Accepted: 09/10/2021] [Indexed: 11/19/2022] Open
Abstract
Background Infectious disease risk is driven by three interrelated components: exposure, hazard, and vulnerability. For schistosomiasis, exposure occurs through contact with water, which is often tied to daily activities. Water contact, however, does not imply risk unless the environmental hazard of snails and parasites is also present in the water. By increasing reliance on hazardous activities and environments, socio-economic vulnerability can hinder reductions in exposure to a hazard. We aimed to quantify the contributions of exposure, hazard, and vulnerability to the presence and intensity of Schistosoma haematobium re-infection. Methodology/Principal findings In 13 villages along the Senegal River, we collected parasitological data from 821 school-aged children, survey data from 411 households where those children resided, and ecological data from all 24 village water access sites. We fit mixed-effects logistic and negative binomial regressions with indices of exposure, hazard, and vulnerability as explanatory variables of Schistosoma haematobium presence and intensity, respectively, controlling for demographic variables. Using multi-model inference to calculate the relative importance of each component of risk, we found that hazard (Ʃwi = 0.95) was the most important component of S. haematobium presence, followed by vulnerability (Ʃwi = 0.91). Exposure (Ʃwi = 1.00) was the most important component of S. haematobium intensity, followed by hazard (Ʃwi = 0.77). Model averaging quantified associations between each infection outcome and indices of exposure, hazard, and vulnerability, revealing a positive association between hazard and infection presence (OR = 1.49, 95% CI 1.12, 1.97), and a positive association between exposure and infection intensity (RR 2.59–3.86, depending on the category; all 95% CIs above 1) Conclusions/Significance Our findings underscore the linkages between social (exposure and vulnerability) and environmental (hazard) processes in the acquisition and accumulation of S. haematobium infection. This approach highlights the importance of implementing both social and environmental interventions to complement mass drug administration. While the impacts of natural hazards tend to be described in terms of social determinants such as exposure and vulnerability, the risk for infectious disease is often expressed in terms of environmental determinants without fully considering the socio-ecological processes that put people in contact with infective agents of disease. In the case of schistosomiasis, risk is determined by human interactions with freshwater environments where schistosome parasites circulate between people and aquatic snails. In this study, we quantified the relative contributions of exposure, hazard, and vulnerability to schistosome re-infection among schoolchildren in an endemic region of northern Senegal. We find that hazard and vulnerability influence whether a child becomes infected, while exposure and hazard influence the burden of worms once infection is acquired. Increasing numbers of worms is known to be positively associated with increasing severity of disease. Our findings underscore the importance of evaluating social and environmental determinants of disease simultaneously; omitting measures of exposure, hazard or vulnerability may limit our understanding of risk.
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Affiliation(s)
- Andrea J. Lund
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Susanne H. Sokolow
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - Isabel J. Jones
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
| | - Chelsea L. Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, United States of America
| | - Sofia Ali
- Stanford University, Stanford, California, United States of America
| | - Andrew Chamberlin
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
| | - Alioune Badara Sy
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
| | - M. Moustapha Sam
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
| | - Nicolas Jouanard
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
- Station d’Innovation Aquacole, Saint Louis, Sénégal
| | - Anne-Marie Schacht
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
- University of Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, Center for Infection and Immunity of Lille, Lille, France
| | - Simon Senghor
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
| | - Assane Fall
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
| | - Raphael Ndione
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
| | - Gilles Riveau
- Centre de Recherche Biomédicale–Espoir Pour La Sante, Saint Louis, Sénégal
- University of Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, Center for Infection and Immunity of Lille, Lille, France
| | - Giulio A. De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - David López-Carr
- Department of Geography, University of California, Santa Barbara, CA, United States of America
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20
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Jones IJ, Sokolow SH, Chamberlin AJ, Lund AJ, Jouanard N, Bandagny L, Ndione R, Senghor S, Schacht AM, Riveau G, Hopkins SR, Rohr JR, Remais JV, Lafferty KD, Kuris AM, Wood CL, De Leo G. Schistosome infection in Senegal is associated with different spatial extents of risk and ecological drivers for Schistosoma haematobium and S. mansoni. PLoS Negl Trop Dis 2021; 15:e0009712. [PMID: 34570777 PMCID: PMC8476036 DOI: 10.1371/journal.pntd.0009712] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 08/06/2021] [Indexed: 11/17/2022] Open
Abstract
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. Schistosome parasites infect more than 200 million people worldwide, mainly in sub-Saharan Africa, where many people are at-risk for infection by multiple schistosome species simultaneously. To reduce the global burden of schistosomiasis, control of the parasites’ intermediate host–specific species of freshwater snails–has been elevated in priority to complement mass drug administration campaigns in endemic areas. To maximize the efficacy and efficiency of snail control efforts, a better understanding of where to target intermediate host snails is badly needed. This includes a better understanding of the spatial scale at which snails in the environment contribute to human infection risk, and, in co-endemic settings, how ecological determinants of infection risk vary by schistosome species. We used quantitative snail sampling and remotely-sensed data at 16 villages in the Senegal River Basin to compare and contrast ecological correlates and spatial scales of infection risk from freshwater snails that transmit Schistosoma haematobium versus S. mansoni. We found that infection risk for S. haematobium was associated with snail habitat at a larger spatial radius than is typically considered for schistosomiasis monitoring and control, whereas infection risk for S. mansoni was not positively correlated with snail habitat at any spatial sampling radius, but was associated with small water access sites enclosed by emergent vegetation. Our findings highlight the need to consider the different ecological and environmental factors driving the transmission of each schistosome species in co-endemic landscapes.
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Affiliation(s)
- Isabel J Jones
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
| | - Susanne H Sokolow
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America.,Stanford Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - Andrew J Chamberlin
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
| | - Andrea J Lund
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, California, United States of America
| | - Nicolas Jouanard
- Biomedical Research Center EPLS, Saint-Louis, Senegal.,Station d'Innovation Aquacole, Saint-Louis, Senegal
| | | | | | - Simon Senghor
- Biomedical Research Center EPLS, Saint-Louis, Senegal
| | - Anne-Marie Schacht
- Biomedical Research Center EPLS, Saint-Louis, Senegal.,Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Gilles Riveau
- Biomedical Research Center EPLS, Saint-Louis, Senegal.,Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Skylar R Hopkins
- National Center for Ecological Analysis and Synthesis, Santa Barbara, California, United States of America.,Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Jason R Rohr
- Department of Biological Science, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Justin V Remais
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Kevin D Lafferty
- Western Ecological Research Center, United States Geological Survey at Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - Armand M Kuris
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America
| | - Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, United States of America
| | - Giulio De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America.,Stanford Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
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21
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Smith M, Yadav S, Fagunloye OG, Pels NA, Horton DA, Alsultan N, Borns A, Cousin C, Dixon F, Mann VH, Lee C, Brindley PJ, El-Sayed NM, Bridger JM, Knight M. PIWI silencing mechanism involving the retrotransposon nimbus orchestrates resistance to infection with Schistosoma mansoni in the snail vector, Biomphalaria glabrata. PLoS Negl Trop Dis 2021; 15:e0009094. [PMID: 34495959 PMCID: PMC8462715 DOI: 10.1371/journal.pntd.0009094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 09/24/2021] [Accepted: 07/27/2021] [Indexed: 12/23/2022] Open
Abstract
Background Schistosomiasis remains widespread in many regions despite efforts at its elimination. By examining changes in the transcriptome at the host-pathogen interface in the snail Biomphalaria glabrata and the blood fluke Schistosoma mansoni, we previously demonstrated that an early stress response in juvenile snails, manifested by induction of heat shock protein 70 (Hsp 70) and Hsp 90 and of the reverse transcriptase (RT) domain of the B. glabrata non-LTR- retrotransposon, nimbus, were critical for B. glabrata susceptibility to S. mansoni. Subsequently, juvenile B. glabrata BS-90 snails, resistant to S. mansoni at 25°C become susceptible by the F2 generation when maintained at 32°C, indicating an epigenetic response. Methodology/Principal findings To better understand this plasticity in susceptibility of the BS-90 snail, mRNA sequences were examined from S. mansoni exposed juvenile BS-90 snails cultured either at 25°C (non-permissive temperature) or 32°C (permissive). Comparative analysis of transcriptomes from snails cultured at the non-permissive and permissive temperatures revealed that whereas stress related transcripts dominated the transcriptome of susceptible BS-90 juvenile snails at 32°C, transcripts encoding proteins with a role in epigenetics, such as PIWI (BgPiwi), chromobox protein homolog 1 (BgCBx1), histone acetyltransferase (BgHAT), histone deacetylase (BgHDAC) and metallotransferase (BgMT) were highly expressed in those cultured at 25°C. To identify robust candidate transcripts that will underscore the anti-schistosome phenotype in B. glabrata, further validation of the differential expression of the above transcripts was performed by using the resistant BS-90 (25°C) and the BBO2 susceptible snail stock whose genome has now been sequenced and represents an invaluable resource for molecular studies in B. glabrata. A role for BgPiwi in B. glabrata susceptibility to S. mansoni, was further examined by using siRNA corresponding to the BgPiwi encoding transcript to suppress expression of BgPiwi, rendering the resistant BS-90 juvenile snail susceptible to infection at 25°C. Given transposon silencing activity of PIWI as a facet of its role as guardian of the integrity of the genome, we examined the expression of the nimbus RT encoding transcript at 120 min after infection of resistant BS90 piwi-siRNA treated snails. We observed that nimbus RT was upregulated, indicating that modulation of the transcription of the nimbus RT was associated with susceptibility to S. mansoni in BgPiwi-siRNA treated BS-90 snails. Furthermore, treatment of susceptible BBO2 snails with the RT inhibitor lamivudine, before exposure to S. mansoni, blocked S. mansoni infection concurrent with downregulation of the nimbus RT transcript and upregulation of the BgPiwi encoding transcript in the lamivudine-treated, schistosome-exposed susceptible snails. Conclusions and significance These findings support a role for the interplay of BgPiwi and nimbus in the epigenetic modulation of plasticity of resistance/susceptibility in the snail-schistosome relationship. Progress is being made to eliminate schistosomiasis, a tropical disease that remains endemic in the tropics and neotropics. In 2020, WHO proposed controlling the snail population as part of a strategy toward reducing schistosomiasis, a vector borne disease, by 2025. The life cycle of the causative parasite is, however, complex and in the absence of vaccines, new drugs, and access to clean water and sanitation, reduction of schistosomiasis will remain elusive. To break the parasite’s life cycle during the snail stage of its development, a better understanding of the molecular basis of how schistosomes survive, or not, in the snail is required. By examining changes in the transcriptome at the host-pathogen interface in the snail Biomphalaria glabrata and Schistosoma mansoni, we showed that early stress response, manifested by the induction of Heat Shock Proteins (Hsps) and the RT domain of the non-LTR retrotransposon, nimbus, were critical for snail susceptibility. Subsequently, juvenile B. glabrata BS-90 snails, resistant to S. mansoni at 25°C were observed to become susceptible by the F2 generation when maintained at 32°C, indicating an epigenetic response. This study confirms these earlier results and shows an interplay between PIWI and nimbus in the anti-schistosome response in the snail host.
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Affiliation(s)
- Michael Smith
- Howard University, Washington, District of Columbia, United States of America
| | - Swara Yadav
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Olayemi G. Fagunloye
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Nana Adjoa Pels
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Daniel A. Horton
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University, London, United Kingdom
| | - Nashwah Alsultan
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Andrea Borns
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Carolyn Cousin
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Freddie Dixon
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Victoria H. Mann
- Department of Microbiology, Immunology & Tropical Medicine, Research Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, The George Washington University, Washington, District of Columbia, United States of America
| | - Clarence Lee
- Division of Science & Mathematics, University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Paul J. Brindley
- Department of Microbiology, Immunology & Tropical Medicine, Research Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, The George Washington University, Washington, District of Columbia, United States of America
| | - Najib M. El-Sayed
- Department of Cell Biology and Molecular Genetics and Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - Joanna M. Bridger
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University, London, United Kingdom
| | - Matty Knight
- Howard University, Washington, District of Columbia, United States of America
- Department of Microbiology, Immunology & Tropical Medicine, Research Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, The George Washington University, Washington, District of Columbia, United States of America
- * E-mail: ,
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22
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Berger DJ, Crellen T, Lamberton PHL, Allan F, Tracey A, Noonan JD, Kabatereine NB, Tukahebwa EM, Adriko M, Holroyd N, Webster JP, Berriman M, Cotton JA. Whole-genome sequencing of Schistosoma mansoni reveals extensive diversity with limited selection despite mass drug administration. Nat Commun 2021; 12:4776. [PMID: 34362894 PMCID: PMC8346512 DOI: 10.1038/s41467-021-24958-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 07/06/2021] [Indexed: 02/07/2023] Open
Abstract
Control and elimination of the parasitic disease schistosomiasis relies on mass administration of praziquantel. Whilst these programmes reduce infection prevalence and intensity, their impact on parasite transmission and evolution is poorly understood. Here we examine the genomic impact of repeated mass drug administration on Schistosoma mansoni populations with documented reduced praziquantel efficacy. We sequenced whole-genomes of 198 S. mansoni larvae from 34 Ugandan children from regions with contrasting praziquantel exposure. Parasites infecting children from Lake Victoria, a transmission hotspot, form a diverse panmictic population. A single round of treatment did not reduce this diversity with no apparent population contraction caused by long-term praziquantel use. We find evidence of positive selection acting on members of gene families previously implicated in praziquantel action, but detect no high frequency functionally impactful variants. As efforts to eliminate schistosomiasis intensify, our study provides a foundation for genomic surveillance of this major human parasite.
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Affiliation(s)
- Duncan J Berger
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Herts, UK.
| | - Thomas Crellen
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Poppy H L Lamberton
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK
- Institute for Biodiversity, Animal Health, and Comparative Medicine, and Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Fiona Allan
- The Natural History Museum, Department of Life Sciences, London, UK
| | - Alan Tracey
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Jennifer D Noonan
- Institute of Parasitology, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Narcis B Kabatereine
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Edridah M Tukahebwa
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Moses Adriko
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Nancy Holroyd
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Joanne P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Herts, UK.
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK.
| | - Matthew Berriman
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
| | - James A Cotton
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
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23
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Spencer SA, Linder C, Penney JMS, Russell HJ, Hyde K, Sheehy C, Reid A, Andriamasy EH, Raderalazasoa GU, Rakotomampianina DAL, Nandimbiniaina AM, Ranaivoson TN, Andrianiaina A, Cruickshank SM, Bustinduy AL, Stothard JR, Edosoa GT, Rahetilahy AM. Five-Year Follow-Up on the Prevalence and Intensity of Infections of Schistosoma mansoni in a Hard-to-Reach District of Madagascar. Am J Trop Med Hyg 2021; 104:1841-1850. [PMID: 33684064 PMCID: PMC8103437 DOI: 10.4269/ajtmh.20-1433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/10/2021] [Indexed: 01/15/2023] Open
Abstract
Schistosomiasis is a major public health problem in Madagascar. The WHO recommends preventive chemotherapy by mass drug administration (MDA) with praziquantel as the primary approach to control Schistosoma mansoni-related morbidity in endemic populations, alongside complementary interventions such as health education. The impact of annual MDA and health education programs was assessed in the hard-to-reach Marolambo district of eastern Madagascar, an area endemic for S. mansoni. Repeated cross-sectional studies undertaken 2015-2019 examined between 300 and 381 school-aged children (aged 5-14 years) annually. The prevalence and infection intensity of S. mansoni were assessed by urine-circulating cathodic antigen (CCA) dipsticks and coproscopy using Kato-Katz (KK) methodologies. After four rounds of annual MDA, a reduction in S. mansoni prevalence was seen in CCA (93.9% in year 1-87.7% in year 5; P = 0.007) and KK (73.9% in year 1-59.4% in year 5; P < 0.0001). The prevalence of heavy-intensity infections roughly halved from 23.7% to 10.1% (P < 0.0001), and the mean intensity of infection fell by 55.0% (480.2-216.3 eggs per gram of feces). A malacological survey found Biomphalaria pfeifferi snail intermediate hosts in multiple water contact sites including rice paddies, streams, and Nosivolo River. Despite reductions in infection prevalence and intensity, schistosomiasis still poses a significant public health challenge in Marolambo district. Twice yearly MDA cycles and/or community-wide MDA are suggested to better reduce infections. Expanding health education, improving standards of water, sanitation and hygiene, and attention on snail-related control will also be important, especially in rice paddy irrigated areas.
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Affiliation(s)
- Stephen A. Spencer
- Royal United Hospitals Bath NHS Foundation Trust, Bath, United Kingdom;,The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom;,Address correspondence to Stephen A. Spencer, Post-Graduate Medical Centre, Royal United Hospital, Combe Park, Bath BA1 3NG, United Kingdom. E-mail:
| | - Cortland Linder
- The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom
| | - James M. StJ. Penney
- The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom
| | - Hannah J. Russell
- The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom
| | - Kate Hyde
- The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom
| | - Caitlin Sheehy
- The University of Manchester Faculty of Biology Medicine and Health, Manchester Academic Health Centre, Manchester, United Kingdom
| | - Alice Reid
- Unité d’Epidémiologie et de Recherche Clinique, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Emmanuel H. Andriamasy
- Faculté de Médecine, Université d’Antananarivo, Antananarivo, Madagascar;,Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gina U. Raderalazasoa
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Anjara M. Nandimbiniaina
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Tahiry N. Ranaivoson
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Antsa Andrianiaina
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Sheena M. Cruickshank
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Amaya L. Bustinduy
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - J. Russell Stothard
- Unité d’Epidémiologie et de Recherche Clinique, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Glenn T. Edosoa
- World Health Organization, Madagascar Country Office, Antananarivo, Madagascar;,Ministère de la Santé Publique de Madagascar, Antananarivo, Madagascar
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24
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Al-Naseri A, Al-Absi S, El Ridi R, Mahana N. A comprehensive and critical overview of schistosomiasis vaccine candidates. J Parasit Dis 2021; 45:557-580. [PMID: 33935395 PMCID: PMC8068781 DOI: 10.1007/s12639-021-01387-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 03/31/2021] [Indexed: 12/11/2022] Open
Abstract
A digenetic platyhelminth Schistosoma is the causative agent of schistosomiasis, one of the neglected tropical diseases that affect humans and animals in numerous countries in the Middle East, sub-Saharan Africa, South America and China. Several control methods were used for prevention of infection or treatment of acute and chronic disease. Mass drug administration led to reduction in heavy-intensity infections and morbidity, but failed to decrease schistosomiasis prevalence and eliminate transmission, indicating the need to develop anti-schistosome vaccine to prevent infection and parasite transmission. This review summarizes the efficacy and protective capacity of available schistosomiasis vaccine candidates with some insights and future prospects.
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Affiliation(s)
- Aya Al-Naseri
- Zoology Department, Faculty of Science, Cairo Univesity, Giza, 12613 Egypt
| | - Samar Al-Absi
- Zoology Department, Faculty of Science, Cairo Univesity, Giza, 12613 Egypt
| | - Rashika El Ridi
- Zoology Department, Faculty of Science, Cairo Univesity, Giza, 12613 Egypt
| | - Noha Mahana
- Zoology Department, Faculty of Science, Cairo Univesity, Giza, 12613 Egypt
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Mawa PA, Kincaid-Smith J, Tukahebwa EM, Webster JP, Wilson S. Schistosomiasis Morbidity Hotspots: Roles of the Human Host, the Parasite and Their Interface in the Development of Severe Morbidity. Front Immunol 2021; 12:635869. [PMID: 33790908 PMCID: PMC8005546 DOI: 10.3389/fimmu.2021.635869] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/25/2021] [Indexed: 12/14/2022] Open
Abstract
Schistosomiasis is the second most important human parasitic disease in terms of socioeconomic impact, causing great morbidity and mortality, predominantly across the African continent. For intestinal schistosomiasis, severe morbidity manifests as periportal fibrosis (PPF) in which large tracts of macro-fibrosis of the liver, visible by ultrasound, can occlude the main portal vein leading to portal hypertension (PHT), sequelae such as ascites and collateral vasculature, and ultimately fatalities. For urogenital schistosomiasis, severe morbidity manifests as pathology throughout the urinary system and genitals, and is a definitive cause of squamous cell bladder carcinoma. Preventative chemotherapy (PC) programmes, delivered through mass drug administration (MDA) of praziquantel (PZQ), have been at the forefront of schistosomiasis control programmes in sub-Saharan Africa since their commencement in Uganda in 2003. However, despite many successes, 'biological hotspots' (as distinct from 'operational hotspots') of both persistent high transmission and morbidity remain. In some areas, this failure to gain control of schistosomiasis has devastating consequences, with not only persistently high infection intensities, but both "subtle" and severe morbidity remaining prevalent. These hotspots highlight the requirement to revisit research into severe morbidity and its mechanisms, a topic that has been out of favor during times of PC implementation. Indeed, the focality and spatially-structured epidemiology of schistosomiasis, its transmission persistence and the morbidity induced, has long suggested that gene-environmental-interactions playing out at the host-parasite interface are crucial. Here we review evidence of potential unique parasite factors, host factors, and their gene-environmental interactions in terms of explaining differential morbidity profiles in the human host. We then take the situation of schistosomiasis mansoni within the Albertine region of Uganda as a case study in terms of elucidating the factors behind the severe morbidity observed and the avenues and directions for future research currently underway within a new research and clinical trial programme (FibroScHot).
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Affiliation(s)
- Patrice A. Mawa
- Immunomodulation and Vaccines Programme, Medical Research Council-Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, Uganda
- Department of Immunology, Uganda Virus Research Institute, Entebbe, Uganda
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Julien Kincaid-Smith
- Centre for Emerging, Endemic and Exotic Diseases (CEEED), Department of Pathobiology and Population Sciences (PPS), Royal Veterinary College, University of London, Herts, United Kingdom
| | | | - Joanne P. Webster
- Centre for Emerging, Endemic and Exotic Diseases (CEEED), Department of Pathobiology and Population Sciences (PPS), Royal Veterinary College, University of London, Herts, United Kingdom
| | - Shona Wilson
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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Trippler L, Ame SM, Hattendorf J, Juma S, Abubakar S, Ali SM, Kabole F, Rollinson D, Knopp S. Impact of seven years of mass drug administration and recrudescence of Schistosoma haematobium infections after one year of treatment gap in Zanzibar: Repeated cross-sectional studies. PLoS Negl Trop Dis 2021; 15:e0009127. [PMID: 33577601 DOI: 10.1371/journal.pntd.0009127] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 01/12/2021] [Indexed: 11/25/2022] Open
Abstract
Background Considerable progress towards the elimination of urogenital schistosomiasis was made by the Zanzibar Elimination of Schistosomiasis Transmission project from 2012 till 2016, when biannual praziquantel mass drug administration (MDA) alone or with additional snail control or behaviour change interventions were implemented. Annual MDA was continued in 2017 and 2018, but not in 2019, imposing a 16-month treatment gap. We monitored the Schistosoma haematobium prevalence from 2012 till 2020 and assessed recrudescence patterns with focus on 2020. Methodology Repeated cross-sectional surveys were conducted from 2011/12 till 2020 in 90 communities and 90 schools in Zanzibar. Annually, around 4,500 adults and up to 20,000 schoolchildren were surveyed. The S. haematobium prevalence was detected by urine filtration and reagent strips. In 2020, risk factors for infection were investigated using generalized estimated equation models. Principal findings In adults, the apparent S. haematobium prevalence was 3.9% in 2011 and 0.4% in 2020. In schoolchildren, the prevalence decreased from 6.6% in 2012 to 1.2% in 2019 with vicissitudes over the years. Prominent recrudescence of infection from 2.8% in 2019 to 9.1% (+225%) in 2020 was observed in 29 schools with historically moderate prevalences (≥10%). Compared with 2019, reinfection in 2020 was particularly striking in boys aged 9–16 years. Being male was a risk factor for infection in 2020 (adults: odds ratio (OR): 6.24, 95% confidence interval (95% CI): 1.96–19.60; schoolchildren: OR: 2.06, 95% CI: 1.52–2.78). Living near to a natural freshwater body significantly increased the odds of infection in adults (OR: 2.90, CI: 1.12–7.54). Conclusions/Significance After 11 rounds of MDA over 7 years and a 16-month treatment gap, the urogenital schistosomiasis prevalence considerably rebounded in hotspot areas. Future elimination efforts in Zanzibar should focus on re-intensifying MDA plus additional interventions in hotspot areas. In low-prevalence areas, the strategy might be adapted from MDA to targeted surveillance-response. Schistosomiasis is a neglected tropical disease caused by parasitic blood flukes of the genus Schistosoma. On the Zanzibar islands, United Republic of Tanzania, interventions to eliminate urogenital schistosomiasis commenced in 2012. From 2012 to 2016, the population was treated biannually with praziquantel and, additionally, some areas received mollusciciding against the intermediate host snail, or educational measures for behavior change. Mass drug administration (MDA) with praziquantel was continued annually in 2017 and 2018, but not in 2019. As a result of the interventions, the overall S. haematobium prevalence was reduced to 0.4% in adults and 3.4% in schoolchildren in 2020. However, in some areas, the MDA gap in 2019 resulted in a considerable rebound of infections. The recrudescence in 2020 was particularly striking for boys aged 9–16 years. In general, in 2020, male participants had higher odds of infection than females. Adults living near to a natural freshwater body also showed an increased risk of S. haematobium infection. Future elimination efforts in Zanzibar should focus on re-intensifying elimination interventions, including MDA, snail control and behavior change in hotspot areas. In low-prevalence areas, the strategy might be adapted from MDA to targeted interventions, such as surveillance-response.
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Lund AJ, Lopez-carr D, Sokolow SH, Rohr JR, De Leo GA. Agricultural Innovations to Reduce the Health Impacts of Dams. Sustainability 2021; 13:1869. [DOI: 10.3390/su13041869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Dams enable the production of food and renewable energy, making them a crucial tool for both economic development and climate change adaptation in low- and middle-income countries. However, dams may also disrupt traditional livelihood systems and increase the transmission of vector- and water-borne pathogens. These livelihood and health impacts diminish the benefits of dams to rural populations dependent on rivers, as hydrological and ecological alterations change flood regimes, reduce nutrient transport and lead to the loss of biodiversity. We propose four agricultural innovations for promoting equity, health, sustainable development, and climate resilience in dammed watersheds: (1) restoring migratory aquatic species, (2) removing submerged vegetation and transforming it into an agricultural resource, (3) restoring environmental flows and (4) integrating agriculture and aquaculture. As investment in dams accelerates in low- and middle-income countries, appropriately addressing their livelihood and health impacts can improve the sustainability of modern agriculture and economic development in a changing climate.
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Rabone M, Wiethase J, Clark PF, Rollinson D, Cumberlidge N, Emery AM. Endemicity of Paragonimus and paragonimiasis in Sub-Saharan Africa: A systematic review and mapping reveals stability of transmission in endemic foci for a multi-host parasite system. PLoS Negl Trop Dis 2021; 15:e0009120. [PMID: 33544705 PMCID: PMC7891758 DOI: 10.1371/journal.pntd.0009120] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/18/2021] [Accepted: 01/09/2021] [Indexed: 11/19/2022] Open
Abstract
Paragonimiasis is caused by zoonotic trematodes of Paragonimus spp., found in Asia, the Americas and Africa, particularly in tropical regions. These parasites have a complex, multi-host life cycle, with mammalian definitive hosts and larval stages cycling through two intermediate hosts (snails and freshwater decapod crustaceans). In Africa, paragonimiasis is particularly neglected, and remains the only human parasitic disease without a fully characterised life cycle. However paragonimiasis has potentially significant impacts on public health in Africa, and prevalence has likely been underestimated through under-reporting and misdiagnosis as tuberculosis due to a similar clinical presentation. We identified the need to synthesise current knowledge and map endemic foci for African Paragonimus spp. together with Poikilorchis congolensis, a rare, taxonomically distant trematode with a similar distribution and morphology. We present the first systematic review of the literature relating to African paragonimiasis, combined with mapping of all reported occurrences of Paragonimus spp. throughout Africa, from the 1910s to the present. In human surveys, numerous reports of significant recent transmission in Southeast Nigeria were uncovered, with high prevalence and intensity of infection. Overall prevalence was significantly higher for P. uterobilateralis compared to P. africanus across studies. The potential endemicity of P. africanus in Côte d'Ivoire is also reported. In freshwater crab intermediate hosts, differences in prevalence and intensity of either P. uterobilateralis or P. africanus were evident across genera and species, suggesting differences in susceptibility. Mapping showed temporal stability of endemic foci, with the majority of known occurrences of Paragonimus found in the rainforest zone of West and Central Africa, but with several outliers elsewhere on the continent. This suggests substantial under sampling and localised infection where potential host distributions overlap. Our review highlights the urgent need for increased sampling in active disease foci in Africa, particularly using molecular analysis to fully characterise Paragonimus species and their hosts.
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Affiliation(s)
- Muriel Rabone
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, School of Public Health, Faculty of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Joris Wiethase
- Department of Biology, University of York, Wentworth Way, York, United Kingdom
| | - Paul F. Clark
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, United Kingdom
| | - David Rollinson
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, School of Public Health, Faculty of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Neil Cumberlidge
- Department of Biology, Northern Michigan University, Marquette, Michigan, United States of America
| | - Aidan M. Emery
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, School of Public Health, Faculty of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
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Truscott JE, Hardwick RJ, Werkman M, Saravanakumar PK, Manuel M, Ajjampur SSR, Ásbjörnsdóttir KH, Khumbo K, Witek-McManus S, Simwanza J, Cottrell G, Houngbégnon P, Ibikounlé M, Walson JL, Anderson RM. Forecasting the effectiveness of the DeWorm3 trial in interrupting the transmission of soil-transmitted helminths in three study sites in Benin, India and Malawi. Parasit Vectors 2021; 14:67. [PMID: 33472677 PMCID: PMC7818558 DOI: 10.1186/s13071-020-04572-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/29/2020] [Indexed: 11/17/2022] Open
Abstract
Background The DeWorm3 project is an ongoing cluster-randomised trial assessing the feasibility of interrupting the transmission of soil-transmitted helminths (STH) through mass drug administration (MDA) using study sites in India, Malawi and Benin. In this article, we describe an approach which uses a combination of statistical and mathematical methods to forecast the outcome of the trial with respect to its stated goal of reducing the prevalence of infection to below 2%. Methods Our approach is first to define the local patterns of transmission within each study site, which is achieved by statistical inference of key epidemiological parameters using the baseline epidemiological measures of age-related prevalence and intensity of STH infection which have been collected by the DeWorm3 trials team. We use these inferred parameters to calibrate an individual-based stochastic simulation of the trial at the cluster and study site level, which is subsequently run to forecast the future prevalence of STH infections. The simulator takes into account both the uncertainties in parameter estimation and the variability inherent in epidemiological and demographic processes in the simulator. We interpret the forecast results from our simulation with reference to the stated goal of the DeWorm3 trial, to achieve a target of \documentclass[12pt]{minimal}
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\begin{document}$$\le 2\%$$\end{document}≤2% prevalence at a point 24 months post-cessation of MDA. Results Simulated output predicts that the two arms will be distinguishable from each other in all three country sites at the study end point. In India and Malawi, measured prevalence in the intervention arm is below the threshold with a high probability (90% and 95%, respectively), but in Benin the heterogeneity between clusters prevents the arm prevalence from being reduced below the threshold value. At the level of individual study arms within each site, heterogeneity among clusters leads to a very low probability of achieving complete elimination in an intervention arm, yielding a post-study scenario with widespread elimination but a few ‘hot spot’ areas of persisting STH transmission. Conclusions Our results suggest that geographical heterogeneities in transmission intensity and worm aggregation have a large impact on the effect of MDA. It is important to accurately assess cluster-level, or even smaller scale, heterogeneities in factors which influence transmission and aggregation for a clearer perspective on projecting the outcomes of MDA control of STH and other neglected tropical diseases. ![]()
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Affiliation(s)
- James E Truscott
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, London, W2 1PG, UK. .,MRC Centre for Global Infectious Disease Analysis, Imperial College London, St Mary's Campus, London, W2 1PG, UK. .,The DeWorm3 Project, The Natural History Museum, London, SW7 5BD, UK.
| | - Robert J Hardwick
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum, London, SW7 5BD, UK
| | - Marleen Werkman
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | | | - Malathi Manuel
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Sitara S R Ajjampur
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Kristjana H Ásbjörnsdóttir
- The DeWorm3 Project, The Natural History Museum, London, SW7 5BD, UK.,Departments of Global Health, Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, WA, USA
| | - Kalua Khumbo
- Blantyre Institute for Community Outreach, University of Malawi, College of Medicine, Blantyre, Malawi
| | - Stefan Witek-McManus
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - James Simwanza
- Blantyre Institute for Community Outreach, University of Malawi, College of Medicine, Blantyre, Malawi
| | - Gilles Cottrell
- Institut de Recherche pour le Développement, MERIT, Université de Paris, Paris, France
| | - Parfait Houngbégnon
- Institut de Recherche Clinique du Benin, Université d'Abomey-Calavi, Cotonou, Benin
| | - Moudachirou Ibikounlé
- Institut de Recherche Clinique du Benin, Université d'Abomey-Calavi, Cotonou, Benin.,Département de Zoologie, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Cotonou, Benin
| | - Judd L Walson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum, London, SW7 5BD, UK.,Departments of Global Health, Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, WA, USA
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Imperial College London, St Mary's Campus, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum, London, SW7 5BD, UK
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Ouattara M, Diakité NR, Yao PK, Saric J, Coulibaly JT, Assaré RK, Bassa FK, Koné N, Guindo-Coulibaly N, Hattendorf J, Utzinger J, N’Goran EK. Effectiveness of school-based preventive chemotherapy strategies for sustaining the control of schistosomiasis in Côte d'Ivoire: Results of a 5-year cluster randomized trial. PLoS Negl Trop Dis 2021; 15:e0008845. [PMID: 33449924 PMCID: PMC7810315 DOI: 10.1371/journal.pntd.0008845] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 09/30/2020] [Indexed: 11/18/2022] Open
Abstract
Background Preventive chemotherapy using praziquantel is the mainstay for schistosomiasis control. However, there is little evidence on what is supposed to be the most effective school-based treatment strategy to sustain morbidity control. The aim of this study was to compare differences in Schistosoma mansoni prevalence and infection intensity between three different schedules of school-based preventive chemotherapy in an area with moderate prevalence of S. mansoni in Côte d’Ivoire. Methodology Seventy-five schools were randomly assigned to one of three intervention arms: (i) annual school-based preventive chemotherapy with praziquantel (40 mg/kg) over four years; (ii) praziquantel treatment only in the first two years, followed by two years whithout treatment; and (iii) praziquantel treatment in years 1 and 3 without treatment in-between. Cross-sectional parasitologic surveys were carried out prior to each round of preventive chemotherapy. The difference in S. mansoni prevalence and infection intensity was assessed by multiple Kato-Katz thick smears, among children aged 9–12 years at the time of each survey. First-grade children, aged 5–8 years who had never received praziquantel, were also tested at baseline and at the end of the study. Principal findings Overall, 7,410 children aged 9–12 years were examined at baseline and 7,223 at the final survey. The baseline prevalence of S. mansoni was 17.4%, 20.2%, and 25.2% in arms 1, 2, and 3, respectively. In the final year, we observed the lowest prevalence of 10.4% in arm 1, compared to 18.2% in arm 2 and 17.5% in arm 3. The comparison between arms 1 and 2 estimated an odds ratio (OR) of 0.52 but the difference was not statistically significant (95% confidence interval (CI) = 0.23–1.16). Likewise the difference between arms 1 and 3 lacked statistical significance (OR = 0.55, 95% CI = 0.23–1.29). There was no noteworthy difference observed between arms 2 and 3 (OR = 1.06, 95% CI = 0.64–1.75). The lowest S. mansoni fecal egg counts in the final year survey were observed in arm 1 (7.9 eggs per gram of stool (EPG)). However, compared with 11.5 EPG in arm 2 and 15.4 EPG in arm 3, the difference lacked statistical significance. There were 4,812 first-grade children examined at baseline and 4,513 in the final survey. The overall prevalence of S. mansoni in these children slightly decreased in arms 1 (from 4.5% to 3.6%) and 2 (from 4.7% to 4.3%), but increased in arm 3 (from 6.8% to 7.9%). However, there was no significant difference in prevalence and infection intensity observed between study arms. Conclusions/significance The three treatment schedules investigated led to a reduction in the prevalence and intensity of S. mansoni infection among children aged 9–12 years. Comparing intervention arms at the end of the study, no statistically significant differences were observed between annual treatement and the other two treatment schedules, neither in reduction of prevalence nor intensity of infection. It is important to combine our results with those of three sister trials conducted simultaneously in other African countries, before final recommendations can be drawn. The World Health Organization (WHO) recommends preventive chemotherapy with praziquantel as the global strategy for morbidity control of schistosomiasis. The guidelines include target groups and treatment frequencies based on prevalence in school-age children. However, these recommendations are based on expert opinion. The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) put forward a series of cluster-randomized trials in different African countries, including Côte d’Ivoire, to identify the most suitable approach to gain and sustain the control of schistosomiasis. Results from Côte d’Ivoire did not show statistically significant differences between three school-based treatment schedules (i.e., annual treatment over four years; treatment only in the first two years, followed by two years whithout treatment; and treatment every other year without treatment in-between) in reducing prevalence and intensity of Schistosoma mansoni infection among children aged 9–12 years. The results in first-grade children with an age of 5–8 years entering school who had never received deworming drugs showed no significant difference in the prevalence and intensity of S. mansoni infection between the different treatments at the study end, suggesting that the three strategies were not significantly different for reducing the disease transmission in affected communities. However, our data should be combined with other SCORE studies carried out elsewhere in Africa. A meta-analysis including the results of the sister trials could help to conclude and make more generic recommendations.
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Affiliation(s)
- Mamadou Ouattara
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- * E-mail:
| | - Nana R. Diakité
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
| | - Patrick K. Yao
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
| | - Jasmina Saric
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Jean T. Coulibaly
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Rufin K. Assaré
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Fidèle K. Bassa
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
| | - Naférima Koné
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
| | - Négnorogo Guindo-Coulibaly
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
| | - Jan Hattendorf
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Eliézer K. N’Goran
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
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Shen Y, Sung MH, King CH, Binder S, Kittur N, Whalen CC, Colley DG. Modeling Approaches to Predicting Persistent Hotspots in SCORE Studies for Gaining Control of Schistosomiasis Mansoni in Kenya and Tanzania. J Infect Dis 2020; 221:796-803. [PMID: 31621850 PMCID: PMC7026890 DOI: 10.1093/infdis/jiz529] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 10/10/2019] [Indexed: 11/13/2022] Open
Abstract
Background Some villages, labeled “persistent hotspots (PHS),” fail to respond adequately in regard to prevalence and intensity of infection to mass drug administration (MDA) for schistosomiasis. Early identification of PHS, for example, before initiating or after 1 or 2 years of MDA could help guide programmatic decision making. Methods In a study with multiple rounds of MDA, data collected before the third MDA were used to predict PHS. We assessed 6 predictive approaches using data from before MDA and after 2 rounds of annual MDA from Kenya and Tanzania. Results Generalized linear models with variable selection possessed relatively stable performance compared with tree-based methods. Models applied to Kenya data alone or combined data from Kenya and Tanzania could reach over 80% predictive accuracy, whereas predicting PHS for Tanzania was challenging. Models developed from one country and validated in another failed to achieve satisfactory performance. Several Year-3 variables were identified as key predictors. Conclusions Statistical models applied to Year-3 data could help predict PHS and guide program decisions, with infection intensity, prevalence of heavy infections (≥400 eggs/gram of feces), and total prevalence being particularly important factors. Additional studies including more variables and locations could help in developing generalizable models.
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Affiliation(s)
- Ye Shen
- Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, Georgia, USA
| | - Meng-Hsuan Sung
- Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, Georgia, USA
| | - Charles H King
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Nupur Kittur
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Christopher C Whalen
- Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, Georgia, USA.,Global Health Institute, University of Georgia, Athens, Georgia, USA
| | - Daniel G Colley
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA.,Department of Microbiology, University of Georgia, Athens, Georgia, USA
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King CH, Kittur N, Binder S, Campbell CH, N'Goran EK, Meite A, Utzinger J, Olsen A, Magnussen P, Kinung'hi S, Fenwick A, Phillips AE, Gazzinelli-Guimaraes PH, Dhanani N, Ferro J, Karanja DMS, Mwinzi PNM, Montgomery SP, Wiegand RE, Secor WE, Hamidou AA, Garba A, Colley DG. Impact of Different Mass Drug Administration Strategies for Gaining and Sustaining Control of Schistosoma mansoni and Schistosoma haematobium Infection in Africa. Am J Trop Med Hyg 2020; 103:14-23. [PMID: 32400356 PMCID: PMC7351298 DOI: 10.4269/ajtmh.19-0829] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This report summarizes the design and outcomes of randomized controlled operational research trials performed by the Bill & Melinda Gates Foundation–funded Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) from 2009 to 2019. Their goal was to define the effectiveness and test the limitations of current WHO-recommended schistosomiasis control protocols by performing large-scale pragmatic trials to compare the impact of different schedules and coverage regimens of praziquantel mass drug administration (MDA). Although there were limitations to study designs and performance, analysis of their primary outcomes confirmed that all tested regimens of praziquantel MDA significantly reduced local Schistosoma infection prevalence and intensity among school-age children. Secondary analysis suggested that outcomes in locations receiving four annual rounds of MDA were better than those in communities that had treatment holiday years, in which no praziquantel MDA was given. Statistical significance of differences was obscured by a wider-than-expected variation in community-level responses to MDA, defining a persistent hot spot obstacle to MDA success. No MDA schedule led to elimination of infection, even in those communities that started at low prevalence of infection, and it is likely that programs aiming for elimination of transmission will need to add supplemental interventions (e.g., snail control, improvement in water, sanitation and hygiene, and behavior change interventions) to achieve that next stage of control. Recommendations for future implementation research, including exploration of the value of earlier program impact assessment combined with intensification of intervention in hot spot locations, are discussed.
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Affiliation(s)
- Charles H King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio.,Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Nupur Kittur
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Carl H Campbell
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Eliézer K N'Goran
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.,Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Aboulaye Meite
- Programme National de Lutte Contre les Maladies Tropicales Négligées à Chimiothérapie Préventive (PNLMTN-CP), Abidjan, Côte d'Ivoire
| | - Jürg Utzinger
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Annette Olsen
- Section for Parasitology and Aquatic Pathobiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pascal Magnussen
- Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Alan Fenwick
- Schistosomiasis Control Initiative, Imperial College, London, United Kingdom
| | - Anna E Phillips
- Schistosomiasis Control Initiative, Imperial College, London, United Kingdom
| | | | - Neerav Dhanani
- Schistosomiasis Control Initiative, Imperial College, London, United Kingdom
| | - Josefo Ferro
- Catholic University of Mozambique, Beira, Mozambique
| | - Diana M S Karanja
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Pauline N M Mwinzi
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | | | - Ryan E Wiegand
- Centers for Disease Control and Prevention, Atlanta, Georgia.,University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | | | - Amina A Hamidou
- Réseau International Schistosomoses, Environnement, Aménagement et Lutte (RISEAL-Niger), Niamey, Niger
| | - Amadou Garba
- Department of Control of Neglected Tropical Diseases, Preventive Chemotherapy and Transmission Control Unit, World Health Organization, Geneva, Switzerland
| | - Daniel G Colley
- Department of Microbiology, University of Georgia, Athens, Georgia.,Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
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King CH, Yoon N, Wang X, Lo NC, Alsallaq R, Ndeffo-Mbah M, Li E, Gurarie D. Application of Schistosomiasis Consortium for Operational Research and Evaluation Study Findings to Refine Predictive Modeling of Schistosoma mansoni and Schistosoma haematobium Control in Sub-Saharan Africa. Am J Trop Med Hyg 2020; 103:97-104. [PMID: 32400357 PMCID: PMC7351296 DOI: 10.4269/ajtmh.19-0852] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
An essential mission of the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was to help inform global health practices related to the control and elimination of schistosomiasis. To provide more accurate, evidence-based projections of the most likely impact of different control interventions, whether implemented alone or in combination, SCORE supported mathematical modeling teams to provide simulations of community-level Schistosoma infection outcomes in the setting of real or hypothetical programs implementing multiyear mass drug administration (MDA) for parasite control. These models were calibrated using SCORE experience with Schistosoma mansoni and Schistosoma haematobium gaining and sustaining control studies, and with data from comparable programs that used community-based or school-based praziquantel MDA in other parts of sub-Saharan Africa. From 2010 to 2019, models were developed and refined, first to project the likely SCORE control outcomes, and later to more accurately reflect impact of MDA across different transmission settings, including the role of snail ecology and the impact of seasonal rainfall on snail abundance. Starting in 2014, SCORE modeling projections were also compared with the models of colleagues in the Neglected Tropical Diseases Modelling Consortium. To explore further possible improvement to program-based control, later simulations examined the cost-effectiveness of combining MDA with environmental snail control, and the utility of early impact assessment to more quickly identify persistent hot spots of transmission. This article provides a nontechnical summary of the 11 SCORE-related modeling projects and provides links to the original open-access articles describing model development and projections relevant to schistosomiasis control policy.
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Affiliation(s)
- Charles H King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio.,Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Nara Yoon
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, Ohio
| | - Xiaoxia Wang
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, Ohio
| | - Nathan C Lo
- Department of Medicine, University of California, San Francisco, San Francisco, California
| | - Ramzi Alsallaq
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | | | - Emily Li
- School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - David Gurarie
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, Ohio.,Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
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Colley DG, Jacobson JA, Binder S. Schistosomiasis Consortium for Operational Research and Evaluation (SCORE): Its Foundations, Development, and Evolution. Am J Trop Med Hyg 2020; 103:5-13. [PMID: 32400343 PMCID: PMC7351300 DOI: 10.4269/ajtmh.19-0785] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was established in late 2008 to conduct operational research that would inform practices related to the control and elimination of schistosomiasis. This article traces SCORE’s beginnings and underpinnings. These include an emphasis on openness and contributing to the development of a cohesive schistosomiasis control community, building linkages between researchers and national programs, and focusing on answering questions that will help Neglected Tropical Disease program managers to better control and eliminate schistosomiasis. It describes the development and implementation of SCORE’s multiple projects. SCORE began by drawing on advice from a broad range of experts by holding wide-ranging meetings that informed the priorities and protocols for SCORE research. SCORE’s major efforts included large, multicountry field studies comparing multiple strategies for mass drug administration with praziquantel, assessment of approaches to elimination, evaluation of a point-of-care assay for field mapping Schistosoma mansoni, and increasing the sensitivity of a laboratory-based diagnostic. SCORE also supported studies on morbidity due to schistosomiasis, quantification of vector snails and the detection of schistosome infections in snails, and changes in schistosome population genetics under praziquantel drug pressure. SCORE data and specimens are archived and will remain available for future research. Although much remains to be carried out, our hope is that through the already published articles and SCORE results described in this supplement, we will have provided a body of evidence to assist policy makers in the development of judicious guidelines for the control and elimination of schistosomiasis.
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Affiliation(s)
- Daniel G Colley
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia.,Department of Microbiology, University of Georgia, Athens, Georgia
| | | | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
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Kittur N, Campbell CH, Binder S, Shen Y, Wiegand RE, Mwanga JR, Kinung'hi SM, Musuva RM, Odiere MR, Matendechero SH, Knopp S, Colley DG. Discovering, Defining, and Summarizing Persistent Hotspots in SCORE Studies. Am J Trop Med Hyg 2020; 103:24-29. [PMID: 32400365 PMCID: PMC7351310 DOI: 10.4269/ajtmh.19-0815] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) conducted large field studies on schistosomiasis control and elimination in Africa. All of these studies, carried out in low-, moderate-, and high-prevalence areas, resulted in a reduction in prevalence and intensity of Schistosoma infection after repeated mass drug administration (MDA). However, in all studies, there were locations that experienced minimal or no decline or even increased in prevalence and/or intensity. These areas are termed persistent hotspots (PHS). In SCORE studies in medium- to high-prevalence areas, at least 30% of study villages were PHS. There was no consistent relationship between PHS and the type or frequency of intervention, adequacy of reported MDA coverage, and prevalence or intensity of infection at baseline. In a series of small studies, factors that differed between PHS and villages that responded to repeated MDA as expected included sources of water for personal use, sanitation, and hygiene. SCORE studies comparing PHS with villages that responded to MDA suggest the potential for PHS to be identified after a few years of MDA. However, additional studies in different social-ecological settings are needed to develop generalizable approaches that program managers can use to identify and address PHS. This is essential if goals for schistosomiasis control and elimination are to be achieved.
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Affiliation(s)
- Nupur Kittur
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Carl H Campbell
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Ye Shen
- Department of Epidemiology & Biostatistics, University of Georgia, Athens, Georgia
| | - Ryan E Wiegand
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Joseph R Mwanga
- Department of Epidemiology, Biostatistics and Behavioral Sciences, School of Public Health, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Safari M Kinung'hi
- Mwanza Research Centre, National Institute of Medical Research, Mwanza, Tanzania
| | - Rosemary M Musuva
- Neglected Tropical Diseases Unit, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Maurice R Odiere
- Neglected Tropical Diseases Unit, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Sultani H Matendechero
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Nairobi, Kenya
| | - Stefanie Knopp
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Daniel G Colley
- Department of Microbiology, University of Georgia, Athens, Georgia.,Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
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Colley DG, Fleming FM, Matendechero SH, Knopp S, Rollinson D, Utzinger J, Castleman JD, Kittur N, King CH, Campbell CH, Kabole FM, Kinung'hi S, Ramzy RMR, Binder S. Contributions of the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) to Schistosomiasis Control and Elimination: Key Findings and Messages for Future Goals, Thresholds, and Operational Research. Am J Trop Med Hyg 2020; 103:125-134. [PMID: 32400345 PMCID: PMC7351304 DOI: 10.4269/ajtmh.19-0787] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Herein, we summarize what we consider are major contributions resulting from the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) program, including its key findings and key messages from those findings. Briefly, SCORE's key findings are as follows: i) biennial mass drug administration (MDA) with praziquantel can control schistosomiasis to moderate levels of prevalence; ii) MDA alone will not achieve elimination; iii) to attain and sustain control throughout endemic areas, persistent hotspots need to be identified following a minimal number of years of annual MDA and controlled through adaptive strategies; iv) annual MDA is more effective than biennial MDA in high-prevalence areas; v) the current World Health Organization thresholds for decision-making based on the prevalence of heavy infections should be redefined; and vi) point-of-care circulating cathodic antigen urine assays are useful for Schistosoma mansoni mapping in low-to-moderate prevalence areas. The data and specimens collected and curated through SCORE efforts will continue to be critical resource for future research. Besides providing useful information for program managers and revision of guidelines for schistosomiasis control and elimination, SCORE research and outcomes have identified additional questions that need to be answered as the schistosomiasis community continues to implement effective, evidence-based programs. An overarching contribution of SCORE has been increased cohesiveness within the schistosomiasis field-oriented community, thereby fostering new and productive collaborations. Based on SCORE's findings and experiences, we propose new approaches, thresholds, targets, and goals for control and elimination of schistosomiasis, and recommend research and evaluation activities to achieve these targets and goals.
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Affiliation(s)
- Daniel G Colley
- Department of Microbiology, University of Georgia, Athens, Georgia.,Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Fiona M Fleming
- Department of Infectious Disease Epidemiology, Schistosomiasis Control Initiative, London, United Kingdom
| | - Sultani H Matendechero
- Division of Communicable Disease Prevention and Control, Neglected Tropical Diseases Unit, Ministry of Health, Nairobi, Kenya
| | - Stefanie Knopp
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Department of Life Sciences, Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - David Rollinson
- Department of Life Sciences, Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - Jürg Utzinger
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Jennifer D Castleman
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Nupur Kittur
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Charles H King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio.,Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Carl H Campbell
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Fatma M Kabole
- Neglected Diseases Programme, Ministry of Health of Zanzibar, Zanzibar, United Republic of Tanzania
| | - Safari Kinung'hi
- National Institute for Medical Research (NIMR), Mwanza Centre, Mwanza, United Republic of Tanzania
| | - Reda M R Ramzy
- National Nutrition Institute, General Organization for Teaching Hospitals and Institutes, Cairo, Egypt
| | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
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Arnold BF, Kanyi H, Njenga SM, Rawago FO, Priest JW, Secor WE, Lammie PJ, Won KY, Odiere MR. Fine-scale heterogeneity in Schistosoma mansoni force of infection measured through antibody response. Proc Natl Acad Sci U S A 2020; 117:23174-81. [PMID: 32868437 DOI: 10.1073/pnas.2008951117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Schistosomiasis is one of the most common parasitic diseases in the world, and most infected people (90%) live in Africa. Global control efforts use measures of population-level transmission to target programs and assess progress toward elimination. Monitoring Schistosoma mansoni transmission has traditionally relied on examining stool with microscopy, which is difficult to scale in large programs and has low sensitivity as infection burdens decline. Our results show that antibody-based measures of transmission align well with stool-based measures, provide higher sensitivity at lower levels of transmission, and enable fine-scale estimates of force of infection by geography and age. The findings represent a major step toward use of serosurveillance to guide schistosomiasis control efforts in Africa. Schistosomiasis is among the most common parasitic diseases in the world, with over 142 million people infected in low- and middle-income countries. Measuring population-level transmission is centrally important in guiding schistosomiasis control programs. Traditionally, human Schistosoma mansoni infections have been detected using stool microscopy, which is logistically difficult at program scale and has low sensitivity when people have low infection burdens. We compared serological measures of transmission based on antibody response to S. mansoni soluble egg antigen (SEA) with stool-based measures of infection among 3,663 preschool-age children in an area endemic for S. mansoni in western Kenya. We estimated force of infection among children using the seroconversion rate and examined how it varied geographically and by age. At the community level, serological measures of transmission aligned with stool-based measures of infection (ρ = 0.94), and serological measures provided more resolution for between-community differences at lower levels of infection. Force of infection showed a clear gradient of transmission with distance from Lake Victoria, with 94% of infections and 93% of seropositive children in communities <1.5 km from the lake. Force of infection increased through age 3 y, by which time 65% (95% CI: 53%, 75%) of children were SEA positive in high-transmission communities—2 y before they would be reached by school-based deworming programs. Our results show that serologic surveillance platforms represent an important opportunity to guide and monitor schistosomiasis control programs, and that in high-transmission settings preschool-age children represent a key population missed by school-based deworming programs.
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Chibwana FD, Tumwebaze I, Mahulu A, Sands AF, Albrecht C. Assessing the diversity and distribution of potential intermediate hosts snails for urogenital schistosomiasis: Bulinus spp. (Gastropoda: Planorbidae) of Lake Victoria. Parasit Vectors 2020; 13:418. [PMID: 32795373 PMCID: PMC7427762 DOI: 10.1186/s13071-020-04281-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 08/03/2020] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The Lake Victoria basin is one of the most persistent hotspots of schistosomiasis in Africa, the intestinal form of the disease being studied more often than the urogenital form. Most schistosomiasis studies have been directed to Schistosoma mansoni and their corresponding intermediate snail hosts of the genus Biomphalaria, while neglecting S. haematobium and their intermediate snail hosts of the genus Bulinus. In the present study, we used DNA sequences from part of the cytochrome c oxidase subunit 1 (cox1) gene and the internal transcribed spacer 2 (ITS2) region to investigate Bulinus populations obtained from a longitudinal survey in Lake Victoria and neighbouring systems during 2010-2019. METHODS Sequences were obtained to (i) determine specimen identities, diversity and phylogenetic positions, (ii) reconstruct phylogeographical affinities, and (iii) determine the population structure to discuss the results and their implications for the transmission and epidemiology of urogenital schistosomiasis in Lake Victoria. RESULTS Phylogenies, species delimitation methods (SDMs) and statistical parsimony networks revealed the presence of two main groups of Bulinus species occurring in Lake Victoria; B. truncatus/B. tropicus complex with three species (B. truncatus, B. tropicus and Bulinus sp. 1), dominating the lake proper, and a B. africanus group, prevalent in banks and marshes. Although a total of 47 cox1 haplotypes, were detected within and outside Lake Victoria, there was limited haplotype sharing (only Haplotype 6 was shared between populations from Lake Victoria open waters and neighbouring aquatic systems) - an indication that haplotypes are specific to habitats. CONCLUSIONS The Bulinus fauna of Lake Victoria consists of at least B. truncatus, B. tropicus, Bulinus sp. 1 (B. trigonus?) and B. ugandae. The occurrence and wide distribution of Bulinus species in Lake Victoria potentially implies the occurrence of urogenital schistosomiasis in communities living along the shores and on islands of the lake who depend solely on the lake for their livelihood. More in-depth studies are needed to obtain a better picture of the extent of the disease in the Lake Victoria basin.
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Affiliation(s)
- Fred D. Chibwana
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Immaculate Tumwebaze
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
| | - Anna Mahulu
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
| | - Arthur F. Sands
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
| | - Christian Albrecht
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
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Turner HC, French MD, Montresor A, King CH, Rollinson D, Toor J. Economic evaluations of human schistosomiasis interventions: a systematic review and identification of associated research needs. Wellcome Open Res 2020; 5:45. [PMID: 32587899 PMCID: PMC7308887 DOI: 10.12688/wellcomeopenres.15754.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2020] [Indexed: 12/12/2022] Open
Abstract
Background: Schistosomiasis is one of the most prevalent neglected tropical diseases (NTDs) with an estimated 229 million people requiring preventive treatment worldwide. Recommendations for preventive chemotherapy strategies have been made by the World Health Organization (WHO) whereby the frequency of treatment is determined by the settings prevalence. Despite recent progress, many countries still need to scale up treatment and important questions remain regarding optimal control strategies. This paper presents a systematic review of the economic evaluations of human schistosomiasis interventions. Methods: A systematic review of the literature was conducted on 22nd August 2019 using the PubMed (MEDLINE) and ISI Web of Science electronic databases. The focus was economic evaluations of schistosomiasis interventions, such as cost-effectiveness and cost-benefit analyses. No date or language stipulations were applied to the searches. Results: We identified 53 relevant health economic analyses of schistosomiasis interventions. Most studies related to Schistosoma japonicum followed by S. haematobium. Several studies also included other NTDs. In Africa, most studies evaluated preventive chemotherapy, whereas in China they mostly evaluated programmes using a combination of interventions (such as chemotherapy, snail control and health education). There was wide variation in the methodology and epidemiological settings investigated. A range of effectiveness metrics were used by the different studies. Conclusions: Due to the variation across the identified studies, it was not possible to make definitive policy recommendations. Although, in general, the current WHO recommended preventive chemotherapy approach to control schistosomiasis was found to be cost-effective. This finding has important implications for policymakers, advocacy groups and potential funders. However, there are several important inconsistencies and research gaps (such as how the health benefits of interventions are quantified) that need to be addressed to identify the resources required to achieve schistosomiasis control and elimination.
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Affiliation(s)
- Hugo C. Turner
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, W2 1PG, UK
- Oxford University Clinical Research Unit, Wellcome Africa Asia Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Antonio Montresor
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, USA
| | - David Rollinson
- Global Schistosomiasis Alliance, Natural History Museum, London, UK
| | - Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
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Assaré RK, N’Tamon RN, Bellai LG, Koffi JA, Mathieu TBI, Ouattara M, Hürlimann E, Coulibaly JT, Diabaté S, N’Goran EK, Utzinger J. Characteristics of persistent hotspots of Schistosoma mansoni in western Côte d'Ivoire. Parasit Vectors 2020; 13:337. [PMID: 32616074 PMCID: PMC7333430 DOI: 10.1186/s13071-020-04188-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 06/13/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Preventive chemotherapy with praziquantel is the cornerstone of schistosomiasis control. However, in some social-ecological settings, the prevalence and/or intensity of Schistosoma infection does not lower meaningfully despite multiple rounds of preventive chemotherapy, a phenomenon termed persistent hotspot (PHS). We assessed the characteristics of PHS in a Schistosoma mansoni-endemic area of Côte d'Ivoire. METHODS In October 2016, a cross-sectional survey was conducted in 14 schools in the western part of Côte d'Ivoire, one year after multiple rounds of preventive chemotherapy. In each school, 50 children aged 9-12 years provided two stool samples and one urine sample. Stool samples were subjected to triplicate Kato-Katz thick smears for S. mansoni diagnosis. Urine samples were examined by a filtration method for S. haematobium eggs. PHS was defined as failure to achieve a reduction in the prevalence of S. mansoni infection of at least 35% and/or a reduction of infection intensity of at least 50%. Six schools underwent more detailed investigations, including a questionnaire survey for demographic characteristics and a malacological survey. RESULTS In the six schools subjected to detailed investigations, the overall prevalence of S. mansoni and S. haematobium was 9.5% and 2.6%, respectively. Four schools were classified as PHS. The S. mansoni prevalence in the four PHS was 10.9% compared to 6.6% in the remaining two schools. The S. mansoni infection intensity, expressed as arithmetic mean eggs per gram of stool (EPG) among infected children, was 123.8 EPG in PHS and 18.7 EPG in the other two schools. Children bathing in open freshwater bodies were at higher odds of S. mansoni infection (odds ratio: 4.5, 95% confidence interval: 1.6-12.6). A total of 76 human-water contact sites (53 in PHS and 23 in the other schools) were examined and 688 snails were collected, including potential intermediate host snails of Schistosoma (Biomphalaria pfeifferi, Bulinus forskalii, Bu. globosus and Bu. truncatus). CONCLUSION Children in PHS schools bathed more frequently in open freshwater bodies, and hence, they are more exposed to Schistosoma transmission. Our findings call for an integrated control approach, complementing preventive chemotherapy with other interventions, particularly in PHS settings.
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Affiliation(s)
- Rufin K. Assaré
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, CH-4002, Basel, Switzerland
- University of Basel, CH-4003, Basel, Switzerland
| | - Roméo N. N’Tamon
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
| | - Louise G. Bellai
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, CH-4002, Basel, Switzerland
- University of Basel, CH-4003, Basel, Switzerland
| | - Judicaelle A. Koffi
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
- Unité de Formation et de Recherche Science de l’Homme et de la Société, Université Félix Houphouët-Boigny, 08 BP 865, Abidjan 08, Côte d’Ivoire
| | - Tra-Bi I. Mathieu
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
| | - Mamadou Ouattara
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
| | - Eveline Hürlimann
- Swiss Tropical and Public Health Institute, CH-4002, Basel, Switzerland
- University of Basel, CH-4003, Basel, Switzerland
| | - Jean T. Coulibaly
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, CH-4002, Basel, Switzerland
- University of Basel, CH-4003, Basel, Switzerland
| | - Salia Diabaté
- Centre d’Entomologie Médicale et Vétérinaire, 27 BP 529, Abidjan 27, Côte d’Ivoire
| | - Eliézer K. N’Goran
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303, Abidjan 01, Côte d’Ivoire
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, CH-4002, Basel, Switzerland
- University of Basel, CH-4003, Basel, Switzerland
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41
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Walker JW, Kittur N, Binder S, Castleman JD, Drake JM, Campbell CH, King CH, Colley DG. Environmental Predictors of Schistosomiasis Persistent Hotspots following Mass Treatment with Praziquantel. Am J Trop Med Hyg 2020; 102:328-338. [PMID: 31889506 PMCID: PMC7008331 DOI: 10.4269/ajtmh.19-0658] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Schistosomiasis control programs rely heavily on mass drug administration (MDA) campaigns with praziquantel for preventative chemotherapy. Areas where the prevalence and/or intensity of schistosomiasis infection remains high even after several rounds of treatment, termed "persistent hotspots" (PHSs), have been identified in trials of MDA effectiveness conducted by the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) in Kenya, Mozambique, Tanzania, and Côte d'Ivoire. In this analysis, we apply a previously developed set of criteria to classify the PHS status of 531 study villages from five SCORE trials. We then fit logistic regression models to data from SCORE and publically available georeferenced datasets to evaluate the influence of local environmental and population features, pre-intervention infection burden, and treatment scheduling on PHS status in each trial. The frequency of PHS in individual trials ranged from 35.3% to 71.6% in study villages. Significant relationships between PHS status and MDA frequency, distance to freshwater, rainfall, baseline schistosomiasis burden, elevation, land cover type, and village remoteness were each observed in at least one trial, although the strength and direction of these relationships was not always consistent among study sites. These findings suggest that PHSs are driven in part by environmental conditions that modify the risk and frequency of reinfection.
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Affiliation(s)
- Joseph W Walker
- Center for the Ecology of Infectious Disease, University of Georgia, Athens, Georgia.,University of Georgia College of Public Health, Athens, Georgia
| | - Nupur Kittur
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
| | - Sue Binder
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
| | - Jennifer D Castleman
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
| | - John M Drake
- Odum School of Ecology, University of Georgia, Athens, Georgia.,Center for the Ecology of Infectious Disease, University of Georgia, Athens, Georgia
| | - Carl H Campbell
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
| | - Charles H King
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio.,Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
| | - Daniel G Colley
- Department of Microbiology, University of Georgia, Athens, Georgia.,Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia
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42
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Amoah AS, Hoekstra PT, Casacuberta-Partal M, Coffeng LE, Corstjens PLAM, Greco B, van Lieshout L, Lim MD, Markwalter CF, Odiere MR, Reinhard-Rupp J, Roestenberg M, Stothard R, Tchuem Tchuenté LA, de Vlas SJ, van Dam GJ. Sensitive diagnostic tools and targeted drug administration strategies are needed to eliminate schistosomiasis. Lancet Infect Dis 2020; 20:e165-e172. [PMID: 32595046 DOI: 10.1016/s1473-3099(20)30254-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 03/03/2020] [Accepted: 03/23/2020] [Indexed: 11/29/2022]
Abstract
Although preventive chemotherapy has been instrumental in reducing schistosomiasis incidence worldwide, serious challenges remain. These problems include the omission of certain groups from campaigns of mass drug administration, the existence of persistent disease hotspots, and the risk of recrudescent infections. Central to these challenges is the fact that the diagnostic tools currently used to establish the burden of infection are not sensitive enough, especially in low-endemic settings, which results in underestimation of the true prevalence of active Schistosoma spp infections. This central issue necessitates that the current schistosomiasis control strategies recommended by WHO are re-evaluated and, possibly, adapted. More targeted interventions and novel approaches have been used to estimate the prevalence of schistosomiasis, such as establishing infection burden by use of precision mapping, which provides high resolution spatial information that delineates variations in prevalence within a defined geographical area. Such information is instrumental in guiding targeted intervention campaigns. However, the need for highly accurate diagnostic tools in such strategies is a crucial factor that is often neglected. The availability of highly sensitive diagnostic tests also opens up the possibility of applying strategies of sample pooling to reduce the cost of control programmes. To interrupt the transmission of, and eventually eliminate, schistosomiasis, better local targeting of preventive chemotherapy, in combination with highly sensitive diagnostic tools, is crucial.
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Affiliation(s)
- Abena S Amoah
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands; Department of Population Health, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK; Malawi Epidemiology and Intervention Research Unit, Chilumba, Malawi
| | - Pytsje T Hoekstra
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands.
| | | | - Luc E Coffeng
- Department of Public Health, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Paul L A M Corstjens
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Mark D Lim
- Global Health Division, The Bill & Melinda Gates Foundation, Seattle, WA, USA; Global Public Health Programs, American Society for Microbiology, Washington DC, USA
| | - Christine F Markwalter
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Maurice R Odiere
- Neglected Tropical Diseases Unit, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | | | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands; Department of Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | | | - Louis-Albert Tchuem Tchuenté
- Laboratory of Parasitology and Ecology, University of Yaoundé I, Yaoundé, Cameroon; Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
| | - Sake J de Vlas
- Department of Public Health, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Govert J van Dam
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
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43
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Turner HC, French MD, Montresor A, King CH, Rollinson D, Toor J. Economic evaluations of human schistosomiasis interventions: a systematic review and identification of associated research needs. Wellcome Open Res 2020; 5:45. [PMID: 32587899 PMCID: PMC7308887 DOI: 10.12688/wellcomeopenres.15754.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2020] [Indexed: 11/05/2023] Open
Abstract
Background: Schistosomiasis is one of the most prevalent neglected tropical diseases (NTDs) with an estimated 229 million people requiring preventive treatment worldwide. Recommendations for preventive chemotherapy strategies have been made by the World Health Organization (WHO) whereby the frequency of treatment is determined by the settings prevalence. Despite recent progress, many countries still need to scale up treatment and important questions remain regarding optimal control strategies. This paper presents a systematic review of the economic evaluations of human schistosomiasis interventions. Methods: A systematic review of the literature was conducted on 22nd August 2019 using the PubMed (MEDLINE) and ISI Web of Science electronic databases. The focus was economic evaluations of schistosomiasis interventions, such as cost-effectiveness and cost-benefit analyses. No date or language stipulations were applied to the searches. Results: We identified 53 relevant health economic analyses of schistosomiasis interventions. Most studies related to Schistosoma japonicum followed by S. haematobium. Several studies also included other NTDs. In Africa, most studies evaluated preventive chemotherapy, whereas in China they mostly evaluated programmes using a combination of interventions (such as chemotherapy, snail control and health education). There was wide variation in the methodology and epidemiological settings investigated. A range of effectiveness metrics were used by the different studies. Conclusions: Due to the variation across the identified studies, it was not possible to make definitive policy recommendations. Although, in general, the current WHO recommended preventive chemotherapy approach to control schistosomiasis was found to be cost-effective. This finding has important implications for policymakers, advocacy groups and potential funders. However, there are several important inconsistencies and research gaps (such as how the health benefits of interventions are quantified) that need to be addressed to identify the resources required to achieve schistosomiasis control and elimination.
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Affiliation(s)
- Hugo C. Turner
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, W2 1PG, UK
- Oxford University Clinical Research Unit, Wellcome Africa Asia Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Antonio Montresor
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, USA
| | - David Rollinson
- Global Schistosomiasis Alliance, Natural History Museum, London, UK
| | - Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
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