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Kura K, Mutono N, Basáñez MG, Collyer BS, Coffeng LE, Thumbi SM, Anderson RM. How Does Treatment Coverage and Proportion Never Treated Influence the Success of Schistosoma mansoni Elimination as a Public Health Problem by 2030? Clin Infect Dis 2024; 78:S126-S130. [PMID: 38662698 PMCID: PMC11045018 DOI: 10.1093/cid/ciae074] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND The 2030 target for schistosomiasis is elimination as a public health problem (EPHP), achieved when the prevalence of heavy-intensity infection among school-aged children (SAC) reduces to <1%. To achieve this, the new World Health Organization guidelines recommend a broader target of population to include pre-SAC and adults. However, the probability of achieving EPHP should be expected to depend on patterns in repeated uptake of mass drug administration by individuals. METHODS We employed 2 individual-based stochastic models to evaluate the impact of school-based and community-wide treatment and calculated the number of rounds required to achieve EPHP for Schistosoma mansoni by considering various levels of the population never treated (NT). We also considered 2 age-intensity profiles, corresponding to a low and high burden of infection in adults. RESULTS The number of rounds needed to achieve this target depends on the baseline prevalence and the coverage used. For low- and moderate-transmission areas, EPHP can be achieved within 7 years if NT ≤10% and NT <5%, respectively. In high-transmission areas, community-wide treatment with NT <1% is required to achieve EPHP. CONCLUSIONS The higher the intensity of transmission, and the lower the treatment coverage, the lower the acceptable value of NT becomes. Using more efficacious treatment regimens would permit NT values to be marginally higher. A balance between target treatment coverage and NT values may be an adequate treatment strategy depending on the epidemiological setting, but striving to increase coverage and/or minimize NT can shorten program duration.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, United Kingdom
| | - Nyamai Mutono
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Kenya
- Paul G. Allen School for Global Health, Washington State University, Pullman
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, United Kingdom
| | - Benjamin S Collyer
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, United Kingdom
| | - Luc E Coffeng
- Department of Public Health, Erasmus University Medical Center, University Medical Center Rotterdam, The Netherlands
| | - S M Thumbi
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Kenya
- Paul G. Allen School for Global Health, Washington State University, Pullman
- Institute of Immunology and Infection Research, University of Edinburgh, United Kingdom
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, United Kingdom
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2
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Rotejanaprasert C, Chuaicharoen P, Prada JM, Thantithaveewat T, Adisakwattana P, Pan-ngum W. Evaluation of Kato-Katz and multiplex quantitative polymerase chain reaction performance for clinical helminth infections in Thailand using a latent class analysis. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220281. [PMID: 37598708 PMCID: PMC10440171 DOI: 10.1098/rstb.2022.0281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 05/27/2023] [Indexed: 08/22/2023] Open
Abstract
Using an appropriate diagnostic tool is essential to soil-transmitted helminth control and elimination efforts. Kato-Katz (KK) is the most commonly used diagnostic, but recently other tools, such as real-time quantitative polymerase chain reaction (multiplex qPCR), are starting to be employed more. Here, we evaluated the performance of these two diagnostic tools for five helminth species in Thailand. In the absence of a gold standard, diagnostic performance can be evaluated using latent class analysis. Our results suggest that in moderate to high prevalence settings above 2% multiplex qPCR could be more sensitive than KK, this was particularly apparent for Opisthorchis viverrini in the northeastern provinces. However, for low prevalence, both diagnostics suffered from low sensitivity. Specificity of both diagnostics was estimated to be high (above 70%) across all settings. For some specific helminth infection such as O. viverrini, multiplex qPCR is still a preferable choice of diagnostic test. KK performed equally well in detecting Ascaris lumbricoides and Taenia solium when the prevalence is moderate to high (above 2%). Neither test performed well when the prevalence of infection is low (below 2%), and certainly in the case for hookworm and Trichuris trichiura. Combination of two or more diagnostic tests can improve the performance although the cost would be high. Development of new methods for helminth surveillance at the pre-elimination phase is therefore very important. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Chawarat Rotejanaprasert
- Department of Tropical Hygiene, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand
| | | | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | | | - Poom Adisakwattana
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Wirichada Pan-ngum
- Department of Tropical Hygiene, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand
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Kabbas-Piñango E, Arinaitwe M, van Dam GJ, Moses A, Namukuta A, Nankasi AB, Mwima NK, Besigye F, Prada JM, Lamberton PHL. Reproducibility matters: intra- and inter-sample variation of the point-of-care circulating cathodic antigen test in two Schistosoma mansoni endemic areas in Uganda. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220275. [PMID: 37598698 PMCID: PMC10440168 DOI: 10.1098/rstb.2022.0275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023] Open
Abstract
Over 240 million people are infected with schistosomiasis. Detecting Schistosoma mansoni eggs in stool using Kato-Katz thick smears (Kato-Katzs) is highly specific but lacks sensitivity. The urine-based point-of-care circulating cathodic antigen test (POC-CCA) has higher sensitivity, but issues include specificity, discrepancy between batches and interpretation of trace results. A semi-quantitative G-score and latent class analyses making no assumptions about trace readings have helped address some of these issues. However, intra-sample and inter-sample variation remains unknown for POC-CCAs. We collected 3 days of stool and urine from 349 and 621 participants, from high- and moderate-endemicity areas, respectively. We performed duplicate Kato-Katzs and one POC-CCA per sample. In the high-endemicity community, we also performed three POC-CCA technical replicates on one urine sample per participant. Latent class analysis was performed to estimate the relative contribution of intra- (test technical reproducibility) and inter-sample (day-to-day) variation on sensitivity and specificity. Within-sample variation for Kato-Katzs was higher than between-sample, with the opposite true for POC-CCAs. A POC-CCA G3 threshold most accurately assesses individual infections. However, to reach the WHO target product profile of the required 95% specificity for prevalence and monitoring and evaluation, a threshold of G4 is needed, but at the cost of reducing sensitivity. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Elías Kabbas-Piñango
- School of Biodiversity, One Health & Veterinary Medicine, Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Moses Arinaitwe
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Govert J. van Dam
- Department of Parasitology, Leiden University Medical Center, Leiden, 2333 ZA, The Netherlands
| | - Adriko Moses
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Annet Namukuta
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Andrina Barungi Nankasi
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Nicholas Khayinja Mwima
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Fred Besigye
- Vector Borne and NTD Control Division, Bilharzia and Worm Control Program Uganda, Ministry of Health, PO Box 1661, Kampala, Uganda
| | - Joaquin M. Prada
- Department of Comparative Biomedical Sciences, Faculty of Health & Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Poppy H. L. Lamberton
- School of Biodiversity, One Health & Veterinary Medicine, Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Borlase A, Prada JM, Crellen T. Modelling morbidity for neglected tropical diseases: the long and winding road from cumulative exposure to long-term pathology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220279. [PMID: 37598702 PMCID: PMC10440174 DOI: 10.1098/rstb.2022.0279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 07/13/2023] [Indexed: 08/22/2023] Open
Abstract
Reducing the morbidities caused by neglected tropical diseases (NTDs) is a central aim of ongoing disease control programmes. The broad spectrum of pathogens under the umbrella of NTDs lead to a range of negative health outcomes, from malnutrition and anaemia to organ failure, blindness and carcinogenesis. For some NTDs, the most severe clinical manifestations develop over many years of chronic or repeated infection. For these diseases, the association between infection and risk of long-term pathology is generally complex, and the impact of multiple interacting factors, such as age, co-morbidities and host immune response, is often poorly quantified. Mathematical modelling has been used for many years to gain insights into the complex processes underlying the transmission dynamics of infectious diseases; however, long-term morbidities associated with chronic or cumulative exposure are generally not incorporated into dynamic models for NTDs. Here we consider the complexities and challenges for determining the relationship between cumulative pathogen exposure and morbidity at the individual and population levels, drawing on case studies for trachoma, schistosomiasis and foodborne trematodiasis. We explore potential frameworks for explicitly incorporating long-term morbidity into NTD transmission models, and consider the insights such frameworks may bring in terms of policy-relevant projections for the elimination era. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Anna Borlase
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Thomas Crellen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
- School of Biodiversity, One Health & Veterinary Medicine, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, Glasgow G12 8TA, UK
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5
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Bosco A, Ciuca L, Maurelli MP, Vitiello P, Cringoli G, Prada JM, Rinaldi L. Comparison of Mini-FLOTAC, Flukefinder and sedimentation techniques for detection and quantification of Fasciola hepatica and Calicophoron daubneyi eggs using spiked and naturally infected bovine faecal samples. Parasit Vectors 2023; 16:260. [PMID: 37533114 PMCID: PMC10399002 DOI: 10.1186/s13071-023-05890-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/19/2023] [Indexed: 08/04/2023] Open
Abstract
BACKGROUND Fasciolosis (Fasciola hepatica) and paramphistomosis (Calicophoron daubneyi) are two important infections of livestock. Calicophoron daubneyi is the predominant Paramphistomidae species in Europe, and its prevalence has increased in the last 10-15 years. In Italy, evidence suggests that the prevalence of F. hepatica in ruminants is low in the southern part, but C. daubneyi has been recently reported at high prevalence in the same area. Given the importance of reliable tools for liver and rumen fluke diagnosis in ruminants, this study evaluated the diagnostic performance of the Mini-FLOTAC (MF), Flukefinder(R) (FF) and sedimentation (SED) techniques to detect and quantify F. hepatica and C. daubneyi eggs using spiked and naturally infected cattle faecal samples. METHODS Briefly, negative bovine faecal samples were artificially spiked with either F. hepatica or C. daubneyi eggs to achieve different egg count levels: 10, 50 and 100 eggs per gram (EPG) of faeces. Moreover, ten naturally infected cattle farms from southern Italy with either F. hepatica and/or C. daubneyi were selected. For each farm, the samples were analysed individually only with MF technique and as pools using MF, FF and SED techniques. Bayesian latent class analysis (LCA) was used to estimate sensitivity and accuracy of the predicted intensity of infection as well as the infection rate in the naturally infected farms. RESULTS The outcome of this study showed that the highest number of eggs (F. hepatica and C. daubneyi) recovered was obtained with MF, followed by FF and SED in spiked infected samples at 50 and 100 EPG, while at lower infection levels of 10 EPG, FF gave the best results. Moreover, the sensitivity for all the techniques included in the study was estimated at > 90% at infection levels > 20 EPG for both F. hepatica and C. daubneyi eggs. However, MF was the most accurate of the three techniques evaluated to estimate fluke infection intensity. Nevertheless, all three techniques can potentially estimate infection rate at farm level accurately. CONCLUSIONS Optimization and standardization of techniques are needed to improve the FEC of fluke eggs.
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Affiliation(s)
- Antonio Bosco
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
| | - Lavinia Ciuca
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
| | - Maria Paola Maurelli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
| | - Paola Vitiello
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
| | - Giuseppe Cringoli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
| | - Joaquin M. Prada
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guilford, UK
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Regional Center for Monitoring Parasitic infections (CREMOPAR), Naples, Italy
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Ogongo P, Nyakundi RK, Chege GK, Ochola L. The Road to Elimination: Current State of Schistosomiasis Research and Progress Towards the End Game. Front Immunol 2022; 13:846108. [PMID: 35592327 PMCID: PMC9112563 DOI: 10.3389/fimmu.2022.846108] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/21/2022] [Indexed: 12/14/2022] Open
Abstract
The new WHO Roadmap for Neglected Tropical Diseases targets the global elimination of schistosomiasis as a public health problem. To date, control strategies have focused on effective diagnostics, mass drug administration, complementary and integrative public health interventions. Non-mammalian intermediate hosts and other vertebrates promote transmission of schistosomiasis and have been utilized as experimental model systems. Experimental animal models that recapitulate schistosomiasis immunology, disease progression, and pathology observed in humans are important in testing and validation of control interventions. We discuss the pivotal value of these models in contributing to elimination of schistosomiasis. Treatment of schistosomiasis relies heavily on mass drug administration of praziquantel whose efficacy is comprised due to re-infections and experimental systems have revealed the inability to kill juvenile schistosomes. In terms of diagnosis, nonhuman primate models have demonstrated the low sensitivity of the gold standard Kato Katz smear technique. Antibody assays are valuable tools for evaluating efficacy of candidate vaccines, and sera from graded infection experiments are useful for evaluating diagnostic sensitivity of different targets. Lastly, the presence of Schistosomes can compromise the efficacy of vaccines to other infectious diseases and its elimination will benefit control programs of the other diseases. As the focus moves towards schistosomiasis elimination, it will be critical to integrate treatment, diagnostics, novel research tools such as sequencing, improved understanding of disease pathogenesis and utilization of experimental models to assist with evaluating performance of new approaches.
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Affiliation(s)
- Paul Ogongo
- Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States.,Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya
| | - Ruth K Nyakundi
- Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya
| | - Gerald K Chege
- Primate Unit & Delft Animal Centre, South African Medical Research Council, Cape Town, South Africa.,Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Lucy Ochola
- Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya.,Department of Environmental Health, School of Behavioural and Lifestyle Sciences, Faculty of Health Sciences, Nelson Mandela University, Gqeberha, South Africa
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7
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Clark J, Moses A, Nankasi A, Faust CL, Moses A, Ajambo D, Besigye F, Atuhaire A, Wamboko A, Carruthers LV, Francoeur R, Tukahebwa EM, Prada JM, Lamberton PHL. Reconciling Egg- and Antigen-Based Estimates of Schistosoma mansoni Clearance and Reinfection: A Modeling Study. Clin Infect Dis 2022; 74:1557-1563. [PMID: 34358299 PMCID: PMC9070857 DOI: 10.1093/cid/ciab679] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Despite decades of interventions, 240 million people have schistosomiasis. Infections cannot be directly observed, and egg-based Kato-Katz thick smears lack sensitivity, affected treatment efficacy and reinfection rate estimates. The point-of-care circulating cathodic antigen (referred to from here as POC-CCA+) test is advocated as an improvement on the Kato-Katz method, but improved estimates are limited by ambiguities in the interpretation of trace results. METHOD We collected repeated Kato-Katz egg counts from 210 school-aged children and scored POC-CCA tests according to the manufacturer's guidelines (referred to from here as POC-CCA+) and the externally developed G score. We used hidden Markov models parameterized with Kato-Katz; Kato-Katz and POC-CCA+; and Kato-Katz and G-Scores, inferring latent clearance and reinfection probabilities at four timepoints over six-months through a more formal statistical reconciliation of these diagnostics than previously conducted. Our approach required minimal but robust assumptions regarding trace interpretations. RESULTS Antigen-based models estimated higher infection prevalence across all timepoints compared with the Kato-Katz model, corresponding to lower clearance and higher reinfection estimates. Specifically, pre-treatment prevalence estimates were 85% (Kato-Katz; 95% CI: 79%-92%), 99% (POC-CCA+; 97%-100%) and 98% (G-Score; 95%-100%). Post-treatment, 93% (Kato-Katz; 88%-96%), 72% (POC-CCA+; 64%-79%) and 65% (G-Score; 57%-73%) of those infected were estimated to clear infection. Of those who cleared infection, 35% (Kato-Katz; 27%-42%), 51% (POC-CCA+; 41%-62%) and 44% (G-Score; 33%-55%) were estimated to have been reinfected by 9-weeks. CONCLUSIONS Treatment impact was shorter-lived than Kato-Katz-based estimates alone suggested, with lower clearance and rapid reinfection. At 3 weeks after treatment, longer-term clearance dynamics are captured. At 9 weeks after treatment, reinfection was captured, but failed clearance could not be distinguished from rapid reinfection. Therefore, frequent sampling is required to understand these important epidemiological dynamics.
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Affiliation(s)
- Jessica Clark
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Christina L Faust
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Adriko Moses
- Vector Control Division, Ministry of Health, Uganda
| | - Diana Ajambo
- Vector Control Division, Ministry of Health, Uganda
| | - Fred Besigye
- Vector Control Division, Ministry of Health, Uganda
| | | | | | - Lauren V Carruthers
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Rachel Francoeur
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
- Faculty of Science & Engineering, University of Chester, Chester, United Kingdom
| | | | - Joaquin M Prada
- Faculty of Health & Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Poppy H L Lamberton
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
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Clark J, Moses A, Nankasi A, Faust CL, Adriko M, Ajambo D, Besigye F, Atuhaire A, Wamboko A, Rowel C, Carruthers LV, Francoeur R, Tukahebwa EM, Lamberton PHL, Prada JM. Translating From Egg- to Antigen-Based Indicators for Schistosoma mansoni Elimination Targets: A Bayesian Latent Class Analysis Study. FRONTIERS IN TROPICAL DISEASES 2022; 3:825721. [PMID: 35784267 PMCID: PMC7612949 DOI: 10.3389/fitd.2022.825721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Schistosomiasis is a parasitic disease affecting over 240-million people. World Health Organization (WHO) targets for Schistosoma mansoni elimination are based on Kato-Katz egg counts, without translation to the widely used, urine-based, point-of-care circulating cathodic antigen diagnostic (POC-CCA). We aimed to standardize POC-CCA score interpretation and translate them to Kato-Katz-based standards, broadening diagnostic utility in progress towards elimination. A Bayesian latent-class model was fit to data from 210 school-aged-children over four timepoints pre- to six-months-post-treatment. We used 1) Kato-Katz and established POC-CCA scoring (Negative, Trace, +, ++ and +++), and 2) Kato-Katz and G-Scores (a new, alternative POC-CCA scoring (G1 to G10)). We established the functional relationship between Kato-Katz counts and POC-CCA scores, and the score-associated probability of true infection. This was combined with measures of sensitivity, specificity, and the area under the curve to determine the optimal POC-CCA scoring system and positivity threshold. A simulation parametrized with model estimates established antigen-based elimination targets. True infection was associated with POC-CCA scores of ≥ + or ≥G3. POC-CCA scores cannot predict Kato-Katz counts because low infection intensities saturate the POC-CCA cassettes. Post-treatment POC-CCA sensitivity/specificity fluctuations indicate a changing relationship between egg excretion and antigen levels (living worms). Elimination targets can be identified by the POC-CCA score distribution in a population. A population with ≤2% ++/+++, or ≤0.5% G7 and above, indicates achieving current WHO Kato-Katz-based elimination targets. Population-level POC-CCA scores can be used to access WHO elimination targets prior to treatment. Caution should be exercised on an individual level and following treatment, as POC-CCAs lack resolution to discern between WHO Kato-Katz-based moderate- and high-intensity-infection categories, with limited use in certain settings and evaluations.
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Affiliation(s)
- Jessica Clark
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Arinaitwe Moses
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Andrina Nankasi
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Christina L. Faust
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Moses Adriko
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Diana Ajambo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Fred Besigye
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Arron Atuhaire
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Aidah Wamboko
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Candia Rowel
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Lauren V. Carruthers
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Rachel Francoeur
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
- Faculty of Science and Engineering, University of Chester, Chester, United Kingdom
| | | | - Poppy H. L. Lamberton
- Wellcome Centre for Integrative Parasitology, Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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Kura K, Ayabina D, Hollingsworth TD, Anderson RM. Determining the optimal strategies to achieve elimination of transmission for Schistosoma mansoni. Parasit Vectors 2022; 15:55. [PMID: 35164842 PMCID: PMC8842958 DOI: 10.1186/s13071-022-05178-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/25/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In January 2021, the World Health Organization published the 2021-2030 roadmap for the control of neglected tropical diseases (NTDs). The goal for schistosomiasis is to achieve elimination as a public health problem (EPHP) and elimination of transmission (EOT) in 78 and 25 countries (by 2030), respectively. Mass drug administration (MDA) of praziquantel continues to be the main strategy for control and elimination. However, as there is limited availability of praziquantel, it is important to determine what volume of treatments are required, who should be targeted and how frequently treatment must be administered to eliminate either transmission or morbidity caused by infection in different endemic settings with varied transmission intensities. METHODS AND RESULTS: In this paper, we employ two individual-based stochastic models of schistosomiasis transmission developed independently by the Imperial College London (ICL) and University of Oxford (SCHISTOX) to determine the optimal treatment strategies to achieve EOT. We find that treating school-age children (SAC) only is not sufficient to achieve EOT within a feasible time frame, regardless of the transmission setting and observed age-intensity of infection profile. Both models show that community-wide treatment is necessary to interrupt transmission in all endemic settings with low, medium and high pristine transmission intensities. CONCLUSIONS The required MDA coverage level to achieve either transmission or morbidity elimination depends on the prevalence prior to the start of treatment and the burden of infection in adults. The higher the worm burden in adults, the higher the coverage levels required for this age category through community-wide treatment programmes. Therefore, it is important that intensity and prevalence data are collected in each age category, particularly from SAC and adults, so that the correct coverage level can be calculated and administered.
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Affiliation(s)
- Klodeta Kura
- grid.512598.2London Centre for Neglected Tropical Disease Research, London, UK ,grid.7445.20000 0001 2113 8111Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, UK ,grid.14105.310000000122478951MRC Centre for Global Infectious Disease Analysis, London, UK
| | - Diepreye Ayabina
- grid.4991.50000 0004 1936 8948Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF UK
| | - T. Deirdre Hollingsworth
- grid.4991.50000 0004 1936 8948Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF UK
| | - Roy M. Anderson
- grid.512598.2London Centre for Neglected Tropical Disease Research, London, UK ,grid.7445.20000 0001 2113 8111Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, UK ,grid.14105.310000000122478951MRC Centre for Global Infectious Disease Analysis, London, UK ,grid.35937.3b0000 0001 2270 9879The DeWorm3 Project, The Natural History Museum of London, London, UK
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10
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Meta-analysis of variable-temperature PCR technique performance for diagnosising Schistosoma japonicum infections in humans in endemic areas. PLoS Negl Trop Dis 2022; 16:e0010136. [PMID: 35030167 PMCID: PMC8794272 DOI: 10.1371/journal.pntd.0010136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 01/27/2022] [Accepted: 01/03/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND As China is moving onto schistosomiasis elimination/eradication, diagnostic methods with both high sensitivity and specificity for Schistosoma japonicum infections in humans are urgently needed. Microscopic identification of eggs in stool is proven to have poor sensitivity in low endemic regions, and antibody tests are unable to distinguish between current and previous infections. Polymerase chain reaction (PCR) technologies for the detection of parasite DNA have been theoretically assumed to show high diagnostic sensitivity and specificity. However, the reported performance of PCR for detecting S. japonicum infection varied greatly among studies. Therefore, we performed a meta-analysis to evaluate the overall diagnostic performance of variable-temperature PCR technologies, based on stool or blood, for detecting S. japonicum infections in humans from endemic areas. METHODS We searched literatures in eight electronic databases, published up to 20 January 2021. The heterogeneity and publication bias of included studies were assessed statistically. The risk of bias and applicability of each eligible study were assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool (QUADAS-2). The bivariate mixed-effects model was applied to obtain the summary estimates of diagnostic performance. The hierarchical summary receiver operating characteristic (HSROC) curve was applied to visually display the results. Subgroup analyses and multivariate regression were performed to explore the source of heterogeneity. This research was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was registered prospectively in PROSPERO (CRD42021233165). RESULTS A total of 2791 papers were retrieved. After assessing for duplications and eligilibity a total of thirteen publications were retained for inclusion. These included eligible data from 4268 participants across sixteen studies. High heterogeneity existed among studies, but no publication bias was found. The pooled analyses of PCR data from all included studies resulted in a sensitivity of 0.91 (95% CI: 0.83 to 0.96), specificity of 0.85 (95% CI: 0.65 to 0.94), positive likelihood ratio of 5.90 (95% CI: 2.40 to 14.60), negative likelihood ratio of 0.10 (95% CI: 0.05 to 0.20) and a diagnostics odds ratio of 58 (95% CI: 19 to 179). Case-control studies showed significantly better performances for PCR diagnostics than cross-sectional studies. This was further evidenced by multivariate analyses. The four types of PCR approaches identified (conventional PCR, qPCR, Droplet digital PCR and nested PCR) differed significantly, with nested PCRs showing the best performance. CONCLUSIONS Variable-temperature PCR has a satisfactory performance for diagnosing S. japonicum infections in humans in endemic areas. More high quality studies on S. japonicum diagnostic techniques, especially in low endemic areas and for the detection of dual-sex and single-sex infections are required. These will likely need to optimise a nested PCR alongside a highly sensitive gene target. They will contribute to successfully monitoring endemic areas as they move towards the WHO 2030 targets, as well as ultimately helping areas to achieve these goals.
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11
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Walker M, Freitas LT, Halder JB, Brack M, Keiser J, King CH, Levecke B, Ai-Lian Lim Y, Pieri O, Sow D, Stothard JR, Webster JP, Zhou XN, Terry RF, Guérin PJ, Basáñez MG. Improving anthelmintic treatment for schistosomiasis and soil-transmitted helminthiases through sharing and reuse of individual participant data. Wellcome Open Res 2022; 7:5. [PMID: 35493199 PMCID: PMC9020536 DOI: 10.12688/wellcomeopenres.17468.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2021] [Indexed: 01/13/2023] Open
Abstract
The Infectious Diseases Data Observatory (IDDO, https://www.iddo.org) has launched a clinical data platform for the collation, curation, standardisation and reuse of individual participant data (IPD) on treatments for two of the most globally important neglected tropical diseases (NTDs), schistosomiasis (SCH) and soil-transmitted helminthiases (STHs). This initiative aims to harness the power of data-sharing by facilitating collaborative joint analyses of pooled datasets to generate robust evidence on the efficacy and safety of anthelminthic treatment regimens. A crucial component of this endeavour has been the development of a Research Agenda to promote engagement with the SCH and STH research and disease control communities by highlighting key questions that could be tackled using data shared through the IDDO platform. Here, we give a contextual overview of the priority research themes articulated in the Research Agenda-a 'living' document hosted on the IDDO website-and describe the three-stage consultation process behind its development. We also discuss the sustainability and future directions of the platform, emphasising throughout the power and promise of ethical and equitable sharing and reuse of clinical data to support the elimination of NTDs.
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Affiliation(s)
- Martin Walker
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, Hatfield, UK
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
- Infectious Diseases Data Observatory, University of Oxford, Oxford, UK
| | - Luzia T. Freitas
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, Hatfield, UK
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
- Infectious Diseases Data Observatory, University of Oxford, Oxford, UK
| | - Julia B. Halder
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, Hatfield, UK
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
- Infectious Diseases Data Observatory, University of Oxford, Oxford, UK
| | - Matthew Brack
- Infectious Diseases Data Observatory, University of Oxford, Oxford, UK
| | - Jennifer Keiser
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
| | - Bruno Levecke
- Department of Translational Physiology, Ghent University, Merelbeke, Belgium
| | - Yvonne Ai-Lian Lim
- Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
| | - Otavio Pieri
- Laboratory of Health and Environment Education, Oswaldo Cruz Institute, Fiocruz, Rio de Janiero, Brazil
| | - Doudou Sow
- Service de Parasitologie, Université Gaston Berger de Saint Louis, Saint Louis, Senegal
| | - J. Russell Stothard
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Joanne P. Webster
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, Hatfield, UK
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, China Center for Disease Control and Prevention, Shanghai, China
| | - Robert F. Terry
- Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | | | - Maria-Gloria Basáñez
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
- Infectious Diseases Data Observatory, University of Oxford, Oxford, UK
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12
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Hoekstra PT, van Dam GJ, van Lieshout L. Context-Specific Procedures for the Diagnosis of Human Schistosomiasis – A Mini Review. FRONTIERS IN TROPICAL DISEASES 2021. [DOI: 10.3389/fitd.2021.722438] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Schistosomiasis is a parasitic disease caused by trematode blood flukes of the genus Schistosoma, affecting over 250 million people mainly in the tropics. Clinically, the disease can present itself with acute symptoms, a stage which is relatively more common in naive travellers originating from non-endemic regions. It can also develop into chronic disease, with the outcome depending on the Schistosoma species involved, the duration and intensity of infection and several host-related factors. A range of diagnostic tests is available to determine Schistosoma infection, including microscopy, antibody detection, antigen detection using the Point-Of-Care Circulating Cathodic Antigen (POC-CCA) test and the Up-Converting Particle Lateral Flow Circulating Anodic Antigen (UCP-LF CAA) test, as well as Nucleic Acid Amplification Tests (NAATs) such as real-time PCR. In this mini review, we discuss these different diagnostic procedures and explore their most appropriate use in context-specific settings. With regard to endemic settings, diagnostic approaches are described based on their suitability for individual diagnosis, monitoring control programs, determining elimination as a public health problem and eventual interruption of transmission. For non-endemic settings, we summarize the most suitable diagnostic approaches for imported cases, either acute or chronic. Additionally, diagnostic options for disease-specific clinical presentations such as genital schistosomiasis and neuro-schistosomiasis are included. Finally, the specific role of diagnostic tests within research settings is described, including a controlled human schistosomiasis infection model and several clinical studies. In conclusion, context-specific settings have different requirements for a diagnostic test, stressing the importance of a well-considered decision of the most suitable diagnostic procedure.
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13
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Bärenbold O, Garba A, Colley DG, Fleming FM, Assaré RK, Tukahebwa EM, Kebede B, Coulibaly JT, N’Goran EK, Tchuem Tchuenté LA, Mwinzi P, Utzinger J, Vounatsou P. Estimating true prevalence of Schistosoma mansoni from population summary measures based on the Kato-Katz diagnostic technique. PLoS Negl Trop Dis 2021; 15:e0009310. [PMID: 33819266 PMCID: PMC8062092 DOI: 10.1371/journal.pntd.0009310] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 04/22/2021] [Accepted: 03/16/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The prevalence of Schistosoma mansoni infection is usually assessed by the Kato-Katz diagnostic technique. However, Kato-Katz thick smears have low sensitivity, especially for light infections. Egg count models fitted on individual level data can adjust for the infection intensity-dependent sensitivity and estimate the 'true' prevalence in a population. However, application of these models is complex and there is a need for adjustments that can be done without modeling expertise. This study provides estimates of the 'true' S. mansoni prevalence from population summary measures of observed prevalence and infection intensity using extensive simulations parametrized with data from different settings in sub-Saharan Africa. METHODOLOGY An individual-level egg count model was applied to Kato-Katz data to determine the S. mansoni infection intensity-dependent sensitivity for various sampling schemes. Observations in populations with varying forces of transmission were simulated, using standard assumptions about the distribution of worms and their mating behavior. Summary measures such as the geometric mean infection, arithmetic mean infection, and the observed prevalence of the simulations were calculated, and parametric statistical models fitted to the summary measures for each sampling scheme. For validation, the simulation-based estimates are compared with an observational dataset not used to inform the simulation. PRINCIPAL FINDINGS Overall, the sensitivity of Kato-Katz in a population varies according to the mean infection intensity. Using a parametric model, which takes into account different sampling schemes varying from single Kato-Katz to triplicate slides over three days, both geometric and arithmetic mean infection intensities improve estimation of sensitivity. The relation between observed and 'true' prevalence is remarkably linear and triplicate slides per day on three consecutive days ensure close to perfect sensitivity. CONCLUSIONS/SIGNIFICANCE Estimation of 'true' S. mansoni prevalence is improved when taking into account geometric or arithmetic mean infection intensity in a population. We supply parametric functions and corresponding estimates of their parameters to calculate the 'true' prevalence for sampling schemes up to 3 days with triplicate Kato-Katz thick smears per day that allow estimation of the 'true' prevalence.
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Affiliation(s)
- Oliver Bärenbold
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Amadou Garba
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Daniel G. Colley
- Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Microbiology, University of Georgia, Athens, Georgia, United States of America
| | - Fiona M. Fleming
- Schistosomiasis Control Initiative, Imperial College, London, United Kingdom
| | - Rufin K. Assaré
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- 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
| | | | | | - Jean T. Coulibaly
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- 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
| | - 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
| | - Louis-Albert Tchuem Tchuenté
- Laboratory of Parasitology and Ecology, University of Yaoundé I, Yaoundé, Cameroon
- Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
| | - Pauline Mwinzi
- Centre for Global Health Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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14
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Toor J, Rollinson D, Turner HC, Gouvras A, King CH, Medley GF, Hollingsworth TD, Anderson RM. Achieving Elimination as a Public Health Problem for Schistosoma mansoni and S. haematobium: When Is Community-Wide Treatment Required? J Infect Dis 2021; 221:S525-S530. [PMID: 31829414 PMCID: PMC7289541 DOI: 10.1093/infdis/jiz609] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The World Health Organization (WHO) has set elimination as a public health problem (EPHP) as a goal for schistosomiasis. As the WHO treatment guidelines for schistosomiasis are currently under revision, we investigate whether school-based or community-wide treatment strategies are required for achieving the EPHP goal. In low- to moderate-transmission settings with good school enrolment, we find that school-based treatment is sufficient for achieving EPHP. However, community-wide treatment is projected to be necessary in certain high-transmission settings as well as settings with low school enrolment. Hence, the optimal treatment strategy depends on setting-specific factors such as the species present, prevalence prior to treatment, and the age profile of infection.
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Affiliation(s)
- Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - David Rollinson
- Department of Life Sciences, Natural History Museum, London, UK.,Global Schistosomiasis Alliance, Department of Life Sciences, Natural History Museum, London, UK
| | - Hugo C Turner
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Anouk Gouvras
- Global Schistosomiasis Alliance, Department of Life Sciences, Natural History Museum, London, UK
| | - Charles H King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
| | - Graham F Medley
- Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, UK
| | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.,Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.,The DeWorm3 Project, Natural History Museum, London, UK
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15
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Koukounari A, Jamil H, Erosheva E, Shiff C, Moustaki I. Latent Class Analysis: Insights about design and analysis of schistosomiasis diagnostic studies. PLoS Negl Trop Dis 2021; 15:e0009042. [PMID: 33539357 PMCID: PMC7888681 DOI: 10.1371/journal.pntd.0009042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 02/17/2021] [Accepted: 12/18/2020] [Indexed: 11/18/2022] Open
Abstract
Various global health initiatives are currently advocating the elimination of schistosomiasis within the next decade. Schistosomiasis is a highly debilitating tropical infectious disease with severe burden of morbidity and thus operational research accurately evaluating diagnostics that quantify the epidemic status for guiding effective strategies is essential. Latent class models (LCMs) have been generally considered in epidemiology and in particular in recent schistosomiasis diagnostic studies as a flexible tool for evaluating diagnostics because assessing the true infection status (via a gold standard) is not possible. However, within the biostatistics literature, classical LCM have already been criticised for real-life problems under violation of the conditional independence (CI) assumption and when applied to a small number of diagnostics (i.e. most often 3-5 diagnostic tests). Solutions of relaxing the CI assumption and accounting for zero-inflation, as well as collecting partial gold standard information, have been proposed, offering the potential for more robust model estimates. In the current article, we examined such approaches in the context of schistosomiasis via analysis of two real datasets and extensive simulation studies. Our main conclusions highlighted poor model fit in low prevalence settings and the necessity of collecting partial gold standard information in such settings in order to improve the accuracy and reduce bias of sensitivity and specificity estimates. Accurate schistosomiasis diagnosis is essential to assess the impact of large scale and repeated mass drug administration to control or even eliminate this disease. However, in schistosomiasis diagnostic studies, several inherent study design issues pose a real challenge for the currently available statistical tools used for diagnostic modelling and associated data analysis and conclusions. More specifically, those study design issues are: 1) the inclusion of small number of diagnostic tests (i.e. most often five), 2) non formal consensus about a schistosomiasis gold standard, 3) the contemporary use of relatively small sample sizes in relevant studies due to lack of research funding, 4) the differing levels of prevalence of the studied disease even within the same area of one endemic country and 5) other real world factors such as: the lack of appropriate equipment, the variability of certain methods due to biological phenomena and training of technicians across the endemic countries because of scarce financial resources contributing to the existing lack of a schistosomiasis gold standard. The current study aims to caution practitioners from blindly applying statistical models with small number of diagnostic tests and sample sizes, proposing design guidelines of future schistosomiasis diagnostic accuracy studies with recommendations for further research. While our study is centred around the diagnosis of schistosomiasis, we feel that the recommendations can be adapted to other major tropical infectious diseases as well.
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Affiliation(s)
- Artemis Koukounari
- Product Development Personalized Health Care, F. Hoffmann-La Roche Ltd., Welwyn Garden, United Kingdom
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- * E-mail:
| | - Haziq Jamil
- Mathematical Sciences, Faculty of Science, Universiti Brunei Darussalam, Bandar Seri Begawan, Brunei
| | - Elena Erosheva
- Department of Statistics, School of Social Work, Center for Statistics and the Social Sciences, University of Washington, Seattle, Washington, United States of America
| | - Clive Shiff
- Molecular Microbiology and Immunology Department, John Hopkins Bloomberg School of Public Health
| | - Irini Moustaki
- Department of Statistics, London School of Economics and Political Science, London, United Kingdom
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16
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Casacuberta-Partal M, Beenakker M, de Dood C, Hoekstra P, Kroon L, Kornelis D, Corstjens P, Hokke CH, van Dam G, Roestenberg M, van Lieshout L. Specificity of the Point-of-Care Urine Strip Test for Schistosoma Circulating Cathodic Antigen (POC-CCA) Tested in Non-Endemic Pregnant Women and Young Children. Am J Trop Med Hyg 2021; 104:1412-1417. [PMID: 33534739 DOI: 10.4269/ajtmh.20-1168] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/25/2020] [Indexed: 01/05/2023] Open
Abstract
The point-of-care urine based strip test for the detection of circulating cathodic antigen (POC-CCA) in schistosome infections is a frequently used tool for diagnosis and mapping of Schistosoma mansoni in school-aged children. Because of its ease of use, the test is increasingly applied to adults and preschool-aged children (PSAC), but its performance has not been specifically evaluated in these target groups. Recent observations have raised concerns about possible reduced specificity, in particular in pregnant women (PW) and PSAC. We thus explored specificity of the POC-CCA urine strip test (Rapid Medical Diagnostics, Pretoria, South Africa) in a non-endemic, nonexposed population of 47 healthy nonpregnant adults (NPAs), 52 PW, and 58 PSAC. A total of 157 urines were tested with POC-CCA, of which five (10.6%) NPAs, 17 (32.7%) PW, and 27 (46.5%) PSAC were positive. The highest scores were found in the youngest babies, with an infant of 9 months being the oldest positive case. On measuring pH, it appeared that all POC-CCA strongly positive urines were acidic (pH range 5-5.5), whereas addition of pH-neutral buffer to a subsample reversed the false positivity. We conclude that the POC-CCA test has reduced specificity in PW and infants younger than 9 months, but that the false positivity might be eliminated by modifications in the buffers used in the test.
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Affiliation(s)
| | - Margreet Beenakker
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Claudia de Dood
- 2Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Pytsje Hoekstra
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Lisa Kroon
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Dieuwke Kornelis
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Paul Corstjens
- 2Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Cornelis H Hokke
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Govert van Dam
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Meta Roestenberg
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands.,3Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Lisette van Lieshout
- 1Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
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17
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Ruberanziza E, Wittmann U, Mbituyumuremyi A, Mutabazi A, Campbell CH, Colley DG, Fleming FM, Ortu G, van Dam GJ, Umulisa I, Tallant J, Kabera M, Semakula M, Corstjens PLAM, Munyaneza T, Lancaster W, Mbonigaba JB, Clements MN. Nationwide Remapping of Schistosoma mansoni Infection in Rwanda Using Circulating Cathodic Antigen Rapid Test: Taking Steps toward Elimination. Am J Trop Med Hyg 2020; 103:315-324. [PMID: 32431276 PMCID: PMC7356434 DOI: 10.4269/ajtmh.19-0866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The field standard for the detection of Schistosoma mansoni infection is Kato–Katz (KK), although it misses many active infections, especially light infections. In 2014, a reassessment of S. mansoni prevalence was conducted in Rwanda using the more sensitive point-of-care circulating cathodic antigen (POC-CCA) rapid assay. A total of 19,371 children from 399 schools were selected for testing for single urine CCA. Of these, 8,697 children from 175 schools were also tested with single stool double-slide KK. Samples from eight of these 175 schools were tested again with CCA and additionally with the highly specific and sensitive up-converting phosphor-lateral flow circulating anodic antigen (UCP-LF CAA) assay. Latent class analysis was applied to all four test results to assess sensitivity and specificity of POC-CCA and estimate the proportion of trace results from Rwanda likely to be true infections. The overall prevalence of S. mansoni infection in Rwanda when CCA trace results were considered negative was 7.4% (school interquartile range [IQR] 0–8%) and 36.1% (school IQR 20–47%) when trace was considered positive. Prevalence by KK was 2.0% with a mean intensity of infection of 1.66 eggs per gram. The proportion of active infections among children diagnosed with CCA trace was estimated by statistical analysis at 61% (Bayesian credibility interval: 50–72%). These results indicate that S. mansoni infection is still widespread in Rwanda and prevalence is much underestimated by KK testing. Circulating cathodic antigen is an affordable alternative to KK and more suitable for measuring S. mansoni prevalence in low-intensity regions.
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Affiliation(s)
- Eugene Ruberanziza
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda.,Neglected Tropical Diseases and Other Parasitic Diseases Unit, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | - Udo Wittmann
- Consult A.G. Statistical Servicesc, Zurich, Switzerland.,SCI Foundation, London, United Kingdom
| | - Aimable Mbituyumuremyi
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | - Alphonse Mutabazi
- Vector Control Unit, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda.,Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | - Carl H Campbell
- Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, Georgia
| | - Daniel G Colley
- Department of Microbiology, University of Georgia, Athens, Georgia.,Schistosomiasis Consortium for Operational Research and Evaluation, Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, Georgia
| | | | | | | | - Irenee Umulisa
- African Leaders Malaria Alliance (ALMA), National Institute of Medical Research Complex, Dar-es-Salam, Tanzania
| | | | - Michee Kabera
- Epidemiology Unit, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda.,Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | - Muhammed Semakula
- HIV/AIDS and STIs Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | | | - Tharcisse Munyaneza
- Microbiology Unit, National Reference Laboratory (NRL) Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | | | - Jean Bosco Mbonigaba
- Neglected Tropical Diseases and Other Parasitic Diseases Unit, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda.,Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | - Michelle N Clements
- MRC Clinical Trials Unit, University College London, London, United Kingdom.,SCI Foundation, London, United Kingdom
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18
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Sousa SRMD, Nogueira JFC, Dias IHL, Fonseca ÁLS, Favero V, Geiger SM, Enk MJ. The use of the circulating cathodic antigen (CCA) urine cassette assay for the diagnosis and assessment of cure of Schistosoma mansoni infections in an endemic area of the Amazon region. Rev Soc Bras Med Trop 2020; 53:e20190562. [PMID: 32997046 PMCID: PMC7523523 DOI: 10.1590/0037-8682-0562-2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 07/20/2020] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Schistosomiasis is a poverty-related disease that affects people in 78
countries worldwide. This study aimed to evaluate the point-of-care
circulating cathodic antigen (POC-CCA) test performance using sensitive
parasitological methods as a reference standard (RS) in individuals before
and after treatment. METHODS The RS was established by combining the results of 16 Kato-Katz slides and
the Helmintex® method. Positivity rates of the POC-CCA test and
Kato-Katz and Helmintex® methods were calculated before treatment
and 30 days afterward. Furthermore, the sensitivity, specificity, accuracy,
and kappa coefficient before treatment were determined by
comparing the methods. The cure rate was defined 30 days after treatment.
RESULTS Among the 217 participants, the RS detected a total of 63 (29.0%) positive
individuals. The POC-CCA test identified 79 (36.4%) infections. The
evaluation of POC-CCA test performance in relation to the RS revealed a
sensitivity of 61.9%, specificity of 74.0%, accuracy of 70.5%, and
kappa coefficient of 0.33. Out of the 53 remaining
participants after treatment, a total of 45 (81.1%) showed egg negative
results, and 8 (18.9%) were egg positive according to the RS. A total of 5
(9.4%) egg-positive and 37 (69.8%) egg-negative individuals were positive by
the POC-CCA test. CONCLUSIONS Our data show that the POC-CCA test has potential as an auxiliary tool for
the diagnosis of Schistosoma mansoni infection, yielding
better results than 16 Kato-Katz slides from three different stool samples.
However, the immunochromatographic test lacks sufficient specificity and
sensitivity for verifying the cure rate after treatment.
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Affiliation(s)
| | | | | | | | - Vivian Favero
- Pontifícia Universidade Católica do Rio Grande do Sul, Brasil
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19
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Betson M, Alonte AJI, Ancog RC, Aquino AMO, Belizario VY, Bordado AMD, Clark J, Corales MCG, Dacuma MG, Divina BP, Dixon MA, Gourley SA, Jimenez JRD, Jones BP, Manalo SMP, Prada JM, van Vliet AHM, Whatley KCL, Paller VGV. Zoonotic transmission of intestinal helminths in southeast Asia: Implications for control and elimination. ADVANCES IN PARASITOLOGY 2020; 108:47-131. [PMID: 32291086 DOI: 10.1016/bs.apar.2020.01.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intestinal helminths are extremely widespread and highly prevalent infections of humans, particularly in rural and poor urban areas of low and middle-income countries. These parasites have chronic and often insidious effects on human health and child development including abdominal problems, anaemia, stunting and wasting. Certain animals play a fundamental role in the transmission of many intestinal helminths to humans. However, the contribution of zoonotic transmission to the overall burden of human intestinal helminth infection and the relative importance of different animal reservoirs remains incomplete. Moreover, control programmes and transmission models for intestinal helminths often do not consider the role of zoonotic reservoirs of infection. Such reservoirs will become increasingly important as control is scaled up and there is a move towards interruption and even elimination of parasite transmission. With a focus on southeast Asia, and the Philippines in particular, this review summarises the major zoonotic intestinal helminths, risk factors for infection and highlights knowledge gaps related to their epidemiology and transmission. Various methodologies are discussed, including parasite genomics, mathematical modelling and socio-economic analysis, that could be employed to improve understanding of intestinal helminth spread, reservoir attribution and the burden associated with infection, as well as assess effectiveness of interventions. For sustainable control and ultimately elimination of intestinal helminths, there is a need to move beyond scheduled mass deworming and to consider animal and environmental reservoirs. A One Health approach to control of intestinal helminths is proposed, integrating interventions targeting humans, animals and the environment, including improved access to water, hygiene and sanitation. This will require coordination and collaboration across different sectors to achieve best health outcomes for all.
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Affiliation(s)
- Martha Betson
- University of Surrey, Guildford, Surrey, United Kingdom.
| | | | - Rico C Ancog
- University of the Philippines Los Baños, Laguna, Philippines
| | | | | | | | - Jessica Clark
- University of Surrey, Guildford, Surrey, United Kingdom
| | | | | | - Billy P Divina
- University of the Philippines Los Baños, Laguna, Philippines
| | | | | | | | - Ben P Jones
- University of Surrey, Guildford, Surrey, United Kingdom
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20
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Deol AK, Fleming FM, Calvo-Urbano B, Walker M, Bucumi V, Gnandou I, Tukahebwa EM, Jemu S, Mwingira UJ, Alkohlani A, Traoré M, Ruberanziza E, Touré S, Basáñez MG, French MD, Webster JP. Schistosomiasis - Assessing Progress toward the 2020 and 2025 Global Goals. N Engl J Med 2019; 381:2519-2528. [PMID: 31881138 PMCID: PMC6785807 DOI: 10.1056/nejmoa1812165] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND With the vision of "a world free of schistosomiasis," the World Health Organization (WHO) set ambitious goals of control of this debilitating disease and its elimination as a public health problem by 2020 and 2025, respectively. As these milestones become imminent, and if programs are to succeed, it is important to evaluate the WHO programmatic guidelines empirically. METHODS We collated and analyzed multiyear cross-sectional data from nine national schistosomiasis control programs (in eight countries in sub-Saharan Africa and in Yemen). Data were analyzed according to schistosome species (Schistosoma mansoni or S. haematobium), number of treatment rounds, overall prevalence, and prevalence of heavy-intensity infection. Disease control was defined as a prevalence of heavy-intensity infection of less than 5% aggregated across sentinel sites, and the elimination target was defined as a prevalence of heavy-intensity infection of less than 1% in all sentinel sites. Heavy-intensity infection was defined as at least 400 eggs per gram of feces for S. mansoni infection or as more than 50 eggs per 10 ml of urine for S. haematobium infection. RESULTS All but one country program (Niger) reached the disease-control target by two treatment rounds or less, which is earlier than projected by current WHO guidelines (5 to 10 years). Programs in areas with low endemicity levels at baseline were more likely to reach both the control and elimination targets than were programs in areas with moderate and high endemicity levels at baseline, although the elimination target was reached only for S. mansoni infection (in Burkina Faso, Burundi, and Rwanda within three treatment rounds). Intracountry variation was evident in the relationships between overall prevalence and heavy-intensity infection (stratified according to treatment rounds), a finding that highlights the challenges of using one metric to define control or elimination across all epidemiologic settings. CONCLUSIONS These data suggest the need to reevaluate progress and treatment strategies in national schistosomiasis control programs more frequently, with local epidemiologic data taken into consideration, in order to determine the treatment effect and appropriate resource allocations and move closer to achieving the global goals. (Funded by the Children's Investment Fund Foundation and others.).
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Affiliation(s)
- Arminder K Deol
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Fiona M Fleming
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Beatriz Calvo-Urbano
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Martin Walker
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Victor Bucumi
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Issah Gnandou
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Edridah M Tukahebwa
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Samuel Jemu
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Upendo J Mwingira
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Abdulhakeem Alkohlani
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Mahamadou Traoré
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Eugene Ruberanziza
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Seydou Touré
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Maria-Gloria Basáñez
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Michael D French
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
| | - Joanne P Webster
- From the Schistosomiasis Control Initiative (A.K.D., F.M.F., B.C.-U.), the London Centre for Neglected Tropical Disease Research (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), the Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Imperial College London (A.K.D., F.M.F., M.W., M.-G.B., J.P.W.), and the Royal Veterinary College, the Department of Pathobiology and Population Sciences, University of London (M.W., J.P.W.) - all in London; the Ministry of Health Burundi, Bujumbura (V.B.); the Ministry of Health Niger, Niamey (I.G.); the Ministry of Health Uganda, Vector Control Division, Kampala (E.M.T.); the Ministry of Health Malawi, Lilongwe (S.J.); the Ministry of Health Tanzania and the National Institute for Medical Research, Dar es Salaam (U.J.M.); the Ministry of Health Yemen, Sana'a (A.A.); the Ministry of Public Health and Hygiene Mali, Bamako (M.T.); the Neglected Tropical Diseases Unit, Malaria and Other Parasitic Diseases Division, Institute of HIV-AIDS, Disease Prevention, and Control, Rwanda Biomedical Center, Ministry of Health, Kigali (E.R.); the National Schistosomiasis Program, Ministry of Health, Ouagadougou, Burkina Faso (S.T.); and RTI International, Washington, DC (M.D.F.)
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Insights from quantitative and mathematical modelling on the proposed WHO 2030 goal for schistosomiasis. Gates Open Res 2019; 3:1517. [PMID: 31701091 DOI: 10.12688/gatesopenres.13052.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2019] [Indexed: 12/14/2022] Open
Abstract
Schistosomiasis remains one of the neglected tropical diseases (NTDs) impacting millions of people around the world. The World Health Organization (WHO) recently proposed a goal of elimination as a public health problem (EPHP) for schistosomiasis to be reached by 2030. Current WHO treatment guidelines for achieving EPHP focus on targeting school-aged children. The NTD Modelling Consortium has developed mathematical models to study schistosomiasis transmission dynamics and the impact of control measures. Our modelling insights on Schistosoma mansoni have shown that EPHP is likely to be attainable in low to moderate prevalence settings using the current guidelines. However, as prevalence rises within high prevalence settings, EPHP is less likely to be achieved unless both school-aged children and adults are treated (with coverage levels increasing with the adult burden of infection). We highlight the challenges that are faced by treatment programmes, such as non-adherence to treatment and resurgence, which can hinder progress towards achieving and maintaining EPHP. Additionally, even though EPHP may be reached, prevalence can still be high due to persisting infections. Therefore, without interruption of transmission, treatment will likely have to continue to maintain EPHP. Further modelling work is being carried out, including extending our results to S. haematobium. By providing these modelling insights, we aim to inform discussions on the goals and treatment guidelines for schistosomiasis.
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Insights from quantitative and mathematical modelling on the proposed WHO 2030 goal for schistosomiasis. Gates Open Res 2019; 3:1517. [PMID: 31701091 PMCID: PMC6820450 DOI: 10.12688/gatesopenres.13052.2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2019] [Indexed: 12/17/2022] Open
Abstract
Schistosomiasis remains one of the neglected tropical diseases (NTDs) impacting millions of people around the world. The World Health Organization (WHO) recently proposed a goal of elimination as a public health problem (EPHP) for schistosomiasis to be reached by 2030. Current WHO treatment guidelines for achieving EPHP focus on targeting school-aged children. The NTD Modelling Consortium has developed mathematical models to study schistosomiasis transmission dynamics and the impact of control measures. Our modelling insights on
Schistosoma mansoni have shown that EPHP is likely to be attainable in low to moderate prevalence settings using the current guidelines. However, as prevalence rises within high prevalence settings, EPHP is less likely to be achieved unless both school-aged children and adults are treated (with coverage levels increasing with the adult burden of infection). We highlight the challenges that are faced by treatment programmes, such as non-adherence to treatment and resurgence, which can hinder progress towards achieving and maintaining EPHP. Additionally, even though EPHP may be reached, prevalence can still be high due to persisting infections. Therefore, without interruption of transmission, treatment will likely have to continue to maintain EPHP. Further modelling work is being carried out, including extending our results to
S. haematobium. By providing these modelling insights, we aim to inform discussions on the goals and treatment guidelines for schistosomiasis.
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23
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Neves MI, Webster JP, Walker M. Estimating helminth burdens using sibship reconstruction. Parasit Vectors 2019; 12:441. [PMID: 31522688 PMCID: PMC6745796 DOI: 10.1186/s13071-019-3687-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/28/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Sibship reconstruction is a form of parentage analysis that can be used to identify the number of helminth parental genotypes infecting individual hosts using genetic data on only their offspring. This has the potential to be used for estimating individual worm burdens when adult parasites are otherwise inaccessible, the case for many of the most globally important human helminthiases and neglected tropical diseases. Yet methods of inferring worm burdens from sibship reconstruction data on numbers of unique parental genotypes are lacking, limiting the method's scope of application. RESULTS We developed a novel statistical method for estimating female worm burdens from data on the number of unique female parental genotypes derived from sibship reconstruction. We illustrate the approach using genotypic data on Schistosoma mansoni (miracidial) offspring collected from schoolchildren in Tanzania. We show how the bias and precision of worm burden estimates critically depends on the number of sampled offspring and we discuss strategies for obtaining sufficient sample sizes and for incorporating judiciously formulated prior information to improve the accuracy of estimates. CONCLUSIONS This work provides a novel approach for estimating individual-level worm burdens using genetic data on helminth offspring. This represents a step towards a wider scope of application of parentage analysis techniques. We discuss how the method could be used to assist in the interpretation of monitoring and evaluation data collected during mass drug administration programmes targeting human helminthiases and to help resolve outstanding questions on key population biological processes that govern the transmission dynamics of these neglected tropical diseases.
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Affiliation(s)
- M Inês Neves
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, UK. .,London Centre for Neglected Tropical Disease Research, London, UK.
| | - Joanne P Webster
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, UK.,London Centre for Neglected Tropical Disease Research, London, UK
| | - Martin Walker
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, UK.,London Centre for Neglected Tropical Disease Research, London, UK
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Toor J, Truscott JE, Werkman M, Turner HC, Phillips AE, King CH, Medley GF, Anderson RM. Determining post-treatment surveillance criteria for predicting the elimination of Schistosoma mansoni transmission. Parasit Vectors 2019; 12:437. [PMID: 31522690 PMCID: PMC6745786 DOI: 10.1186/s13071-019-3611-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/08/2019] [Indexed: 01/11/2023] Open
Abstract
Background The World Health Organization (WHO) has set elimination (interruption of transmission) as an end goal for schistosomiasis. However, there is currently little guidance on the monitoring and evaluation strategy required once very low prevalence levels have been reached to determine whether elimination or resurgence of the disease will occur after stopping mass drug administration (MDA) treatment. Methods We employ a stochastic individual-based model of Schistosoma mansoni transmission and MDA impact to determine a prevalence threshold, i.e. prevalence of infection, which can be used to determine whether elimination or resurgence will occur after stopping treatment with a given probability. Simulations are run for treatment programmes with varying probabilities of achieving elimination and for settings where adults harbour low to high burdens of infection. Prevalence is measured based on using a single Kato-Katz on two samples per individual. We calculate positive predictive values (PPV) using PPV ≥ 0.9 as a reliable measure corresponding to ≥ 90% certainty of elimination. We analyse when post-treatment surveillance should be carried out to predict elimination. We also determine the number of individuals across a single community (of 500–1000 individuals) that should be sampled to predict elimination. Results We find that a prevalence threshold of 1% by single Kato-Katz on two samples per individual is optimal for predicting elimination at two years (or later) after the last round of MDA using a sample size of 200 individuals across the entire community (from all ages). This holds regardless of whether the adults have a low or high burden of infection relative to school-aged children. Conclusions Using a prevalence threshold of 0.5% is sufficient for surveillance six months after the last round of MDA. However, as such a low prevalence can be difficult to measure in the field using Kato-Katz, we recommend using 1% two years after the last round of MDA. Higher prevalence thresholds of 2% or 5% can be used but require waiting over four years for post-treatment surveillance. Although, for treatment programmes where elimination is highly likely, these higher thresholds could be used sooner. Additionally, switching to more sensitive diagnostic techniques, will allow for a higher prevalence threshold to be employed. Electronic supplementary material The online version of this article (10.1186/s13071-019-3611-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jaspreet Toor
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK. .,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, Norfolk Place, London, W2 1PG, UK.
| | - James E Truscott
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK.,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, Norfolk Place, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum of London, London, SW7 5BD, UK
| | - Marleen Werkman
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK.,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, Norfolk Place, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum of London, London, SW7 5BD, UK
| | - Hugo C Turner
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Anna E Phillips
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK.,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, Norfolk Place, London, W2 1PG, UK
| | - Charles H King
- Center for Global Health and Diseases and Department of Mathematics, Case Western Reserve University, 10900 Euclid Avenue LC: 4983, Cleveland, OH, 44106, USA
| | - Graham F Medley
- Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, UK
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK.,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, Norfolk Place, London, W2 1PG, UK.,The DeWorm3 Project, The Natural History Museum of London, London, SW7 5BD, UK
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Nelwan ML. Schistosomiasis: Life Cycle, Diagnosis, and Control. Curr Ther Res Clin Exp 2019; 91:5-9. [PMID: 31372189 PMCID: PMC6658823 DOI: 10.1016/j.curtheres.2019.06.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 06/06/2019] [Indexed: 12/20/2022] Open
Abstract
Three main schistosomiasis species can infect humans; S. haematobium, S. japonicum, and S. mansoni. The parasites life cycle includes two kind of reproduction; asexual reproduction in snails and sexual reproduction in mammals. Multiple diagnostic techniques are used. Currently praziquantel is the only drug therapy approved for control of schistosomiasis but other promising candidate drugs (e.g. SpAE, and ruthenium compounds) are being tested. A number of vaccine candidates exist including SmCB1, SjAChE, and SmCB. Genetic manipulations are being investigated.
Background Human schistosomiasis is a parasitic disease caused by blood-worms that infect multiple organs, including the liver, intestine, bladder, and urethra. This disease may be eliminated with Praziquantel, vaccines, and gene therapy. Aims In this review, the author describes the progress in a study of schistosomiasis that focused on the life cycle, diagnosis, and control. Methodology The author searched the PubMed Database at NCBI for articles on schistosomiasis published between 2014 and 2018. All articles were open access and in English. Results The life cycle of this parasites involve two hosts: snails and mammals. Manifestations of schistosomiasis can be acute or chronic. Clinical manifestations of acute schistosomiasis can include fever and headache. Symptoms of chronic infections can include dysuria and hyperplasia. Infection can occur in several sites including the bile ducts, intestine, and bladder. The different sites of infection and symptoms seen are related to which of the species involved. Five species can infect humans. The three most commons are S. haematobium, S. japonicum, and S. mansoni. Detection tools for people with schistosomiasis can include the Kato-Katz and PCR. Praziquantel is at present the only effective treatment of this disease. In the future, vaccination or gene therapy may be used. Conclusion Kato-Katz and PCR are tools for detecting schistosomiasis on humans. Praziquantel, diagnosis, vaccines, and gene therapy are useful methods for eliminating schistosomiasis.
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Affiliation(s)
- Martin L. Nelwan
- Address correspondence to: Department of Animal Science, Nelwan Institution for Human Resource Development, Jl A Yani No. 24, Palu, Indonesia.
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Bärenbold O, Garba A, Colley DG, Fleming FM, Haggag AA, Ramzy RMR, Assaré RK, Tukahebwa EM, Mbonigaba JB, Bucumi V, Kebede B, Yibi MS, Meité A, Coulibaly JT, N’Goran EK, Tchuem Tchuenté LA, Mwinzi P, Utzinger J, Vounatsou P. Translating preventive chemotherapy prevalence thresholds for Schistosoma mansoni from the Kato-Katz technique into the point-of-care circulating cathodic antigen diagnostic test. PLoS Negl Trop Dis 2018; 12:e0006941. [PMID: 30550594 PMCID: PMC6310297 DOI: 10.1371/journal.pntd.0006941] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 12/28/2018] [Accepted: 10/23/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Intervention guidelines against Schistosoma mansoni are based on the Kato-Katz technique. However, Kato-Katz thick smears show low sensitivity, especially for light-intensity infections. The point-of-care circulating cathodic antigen (POC-CCA) is a promising rapid diagnostic test detecting antigen output of living worms in urine and results are reported as trace, 1+, 2+, and 3+. The use of POC-CCA for schistosomiasis mapping, control, and surveillance requires translation of the Kato-Katz prevalence thresholds into POC-CCA relative treatment cut-offs. Furthermore, the infection status of egg-negative but antigen-positive individuals and the intensity-dependent sensitivity of POC-CCA should be estimated to determine its suitability for verification of disease elimination efforts. METHODOLOGY We used data from settings in Africa and the Americas characterized by a wide range of S. mansoni endemicity. We estimated infection intensity-dependent sensitivity and specificity of each test at the unit of the individual, using a hierarchical Bayesian egg-count model that removes the need to define a 'gold' standard applied to data with multiple Kato-Katz thick smears and POC-CCA urine cassette tests. A simulation study was carried out based on the model estimates to assess the relation of the two diagnostic tests for different endemicity scenarios. PRINCIPAL FINDINGS POC-CCA showed high specificity (> 95%), and high sensitivity (> 95%) for moderate and heavy infection intensities, and moderate sensitivity (> 75%) for light infection intensities, and even for egg-negative but antigen-positive infections. A 10% duplicate slide Kato-Katz thick smear prevalence corresponded to a 15-40% prevalence of ≥ trace-positive POC-CCA, and 10-20% prevalence of ≥ 1+ POC-CCA. The prevalence of ≥ 2+ POC-CCA corresponded directly to single slide Kato-Katz prevalence for all prevalence levels. CONCLUSIONS/SIGNIFICANCE The moderate sensitivity of POC-CCA, even for very light S. mansoni infections where the sensitivity of Kato-Katz is very low, and the identified relationship between Kato-Katz and POC-CCA prevalence thresholds render the latter diagnostic tool useful for surveillance and initial estimation of elimination of S. mansoni. For prevalence below 10% based on a duplicate slide Kato-Katz thick smear, we suggest using POC-CCA including trace results to evaluate treatment needs and propose new intervention thresholds that need to be validated in different settings.
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Affiliation(s)
- Oliver Bärenbold
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Amadou Garba
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Daniel G. Colley
- Center for Tropical and Emerging Global Diseases and Department of Microbiology, University of Georgia, Athens, GA, United States of America
| | - Fiona M. Fleming
- Schistosomiasis Control Initiative, Imperial College, London, United Kingdom
| | | | - Reda M. R. Ramzy
- National Nutrition Institute, General Organisation for Teaching Hospitals and Institutes, Cairo, Egypt
| | - Rufin K. Assaré
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- 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
| | | | | | - Victor Bucumi
- Programme National Intégré de Lutte contre les Maladies Tropicales Négligées et la Cécité au Burundi, Bujumbura, Burundi
| | | | - Makoy S. Yibi
- Neglected Tropical Disease Department, Ministry of Health, Juba, South Sudan
| | - Aboulaye Meité
- Programme National de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive, Ministère de la Santé et de l’Hygiène Publique, Abidjan, Côte d’Ivoire
| | - Jean T. Coulibaly
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- 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
| | - 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
| | - Louis-Albert Tchuem Tchuenté
- Laboratory of Parasitology and Ecology, University of Yaoundé I, Yaoundé, Cameroon
- Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
| | - Pauline Mwinzi
- Centre for Global Health Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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Peralta JM, Cavalcanti MG. Is POC-CCA a truly reliable test for schistosomiasis diagnosis in low endemic areas? The trace results controversy. PLoS Negl Trop Dis 2018; 12:e0006813. [PMID: 30408030 PMCID: PMC6224048 DOI: 10.1371/journal.pntd.0006813] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- José M. Peralta
- Departmento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marta G. Cavalcanti
- Departmento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Serviço de Doenças Infecciosas e Parasitárias, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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Toor J, Turner HC, Truscott JE, Werkman M, Phillips AE, Alsallaq R, Medley GF, King CH, Anderson RM. The design of schistosomiasis monitoring and evaluation programmes: The importance of collecting adult data to inform treatment strategies for Schistosoma mansoni. PLoS Negl Trop Dis 2018; 12:e0006717. [PMID: 30296257 PMCID: PMC6175503 DOI: 10.1371/journal.pntd.0006717] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/24/2018] [Indexed: 12/02/2022] Open
Abstract
Monitoring and evaluation (M&E) programmes are used to collect data which are required to assess the impact of current interventions on their progress towards achieving the World Health Organization (WHO) goals of morbidity control and elimination as a public health problem for schistosomiasis. Prevalence and intensity of infection data are typically collected from school-aged children (SAC) as they are relatively easy to sample and are thought to be most likely to be infected by schistosome parasites. However, adults are also likely to be infected. We use three different age-intensity profiles of infection for Schistosoma mansoni with low, moderate and high burdens of infection in adults to investigate how the age distribution of infection impacts the mathematical model generated recommendations of the preventive chemotherapy coverage levels required to achieve the WHO goals. We find that for moderate prevalence regions, regardless of the burden of infection in adults, treating SAC only may achieve the WHO goals. However, for high prevalence regions with a high burden of infection in adults, adult treatment is required to meet the WHO goals. Hence, we show that the optimal treatment strategy for a defined region requires consideration of the burden of infection in adults as it cannot be based solely on the prevalence of infection in SAC. Although past epidemiological data have informed mathematical models for the transmission and control of schistosome infections, more accurate and detailed data are required from M&E programmes to accurately determine the optimal treatment strategy for a defined region. We highlight the importance of collecting prevalence and intensity of infection data from a broader age-range, specifically the inclusion of adult data at baseline (prior to treatment) and throughout the treatment programme if possible, rather than SAC only, to accurately determine the treatment strategy for a defined region. Furthermore, we discuss additional epidemiological data, such as individual longitudinal adherence to treatment, that should ideally be collected in M&E programmes. Schistosomiasis remains an endemic parasitic disease affecting millions of people around the world. The World Health Organization (WHO) has set goals of morbidity control and elimination as a public health problem for schistosomiasis defined by reaching ≤5% and ≤1% prevalence of heavy-intensity infections in school-aged children, respectively. Monitoring and evaluation (M&E) programmes are used to collect data which can inform treatment strategies required in a defined area and can also aid in assessing the progress of implemented treatment strategies. Due to programmatic and financial constraints, M&E data are typically collected from school-aged children as they are thought to be most likely to be infected. We highlight that adults should be included within M&E programmes by showing how the burden of infection in adults impacts our mathematical model recommendations of the treatment coverage levels required to reach the WHO goals for schistosomiasis. Our results highlight the importance of collecting data from a broader age-range, specifically the inclusion of adult data at baseline (prior to treatment) and throughout the treatment programme if possible. Improving M&E programmes to incorporate collection of such data will allow for more accurate determination of the optimal treatment strategy for a defined region.
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Affiliation(s)
- Jaspreet Toor
- London Centre for Neglected Tropical Disease Research and Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- * E-mail:
| | - Hugo C. Turner
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - James E. Truscott
- London Centre for Neglected Tropical Disease Research and Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
| | - Marleen Werkman
- London Centre for Neglected Tropical Disease Research and Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
| | - Anna E. Phillips
- London Centre for Neglected Tropical Disease Research and Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
| | - Ramzi Alsallaq
- Center for Global Health and Diseases and Department of Mathematics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Graham F. Medley
- Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Charles H. King
- Center for Global Health and Diseases and Department of Mathematics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Roy M. Anderson
- London Centre for Neglected Tropical Disease Research and Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
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Candido RRF, Morassutti AL, Graeff-Teixeira C, St Pierre TG, Jones MK. Exploring Structural and Physical Properties of Schistosome Eggs: Potential Pathways for Novel Diagnostics? ADVANCES IN PARASITOLOGY 2018; 100:209-237. [PMID: 29753339 DOI: 10.1016/bs.apar.2018.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this era of increasing demand for sensitive techniques to diagnose schistosomiasis, there is a need for an increased focus on the properties of the parasite eggs. The eggs are not only directly linked to the morbidity of chronic infection but are also potential key targets for accurate diagnostics. Eggs were the primary target of diagnostic tools in the past and we argue they could be the target of highly sensitive tools in the future if we focus on characteristics of their structure and shell surface that could be exploited for enhanced detection. In this review, we discuss the current state of knowledge of the physical structures of schistosome eggs and eggshells with a view to identifying pathways to a comprehensive understanding of their role in the host-parasite relationship and pathogenesis of infection, and pathways to new strategies for development of diagnostics.
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Affiliation(s)
- Renata R F Candido
- School of Physics, The University of Western Australia, Crawley, WA, Australia.
| | - Alessandra L Morassutti
- School of Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Carlos Graeff-Teixeira
- School of Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Timothy G St Pierre
- School of Physics, The University of Western Australia, Crawley, WA, Australia
| | - Malcolm K Jones
- School of Veterinary Sciences, The University of Queensland, Brisbane, QLD, Australia
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