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Choi YJ, Fischer K, Méité A, Koudou BG, Fischer PU, Mitreva M. Distinguishing recrudescence from reinfection in lymphatic filariasis. EBioMedicine 2024; 105:105188. [PMID: 38848649 PMCID: PMC11200287 DOI: 10.1016/j.ebiom.2024.105188] [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: 11/14/2023] [Revised: 05/21/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND The Global Program to Eliminate Lymphatic Filariasis (GPELF) is the largest public health program based on mass drug administration (MDA). Despite decades of MDA, ongoing transmission in some countries remains a challenge. To optimise interventions, it is critical to differentiate between recrudescence and new infections. Since adult filariae are inaccessible in humans, deriving a method that relies on the offspring microfilariae (mf) is necessary. METHODS We developed a genome amplification and kinship analysis-based approach using Brugia malayi samples from gerbils, and applied it to analyse Wuchereria bancrofti mf from humans in Côte d'Ivoire. We examined the pre-treatment genetic diversity in 269 mf collected from 18 participants, and further analysed 1-year post-treatment samples of 74 mf from 4 participants. Hemizygosity of the male X-chromosome allowed for direct inference of haplotypes, facilitating robust maternal parentage inference. To enrich parasite DNA from samples contaminated with host DNA, a whole-exome capture panel was created for W. bancrofti. FINDINGS By reconstructing and temporally tracking sibling relationships across pre- and post-treatment samples, we differentiated between new and established maternal families, suggesting reinfection in one participant and recrudescence in three participants. The estimated number of reproductively active adult females ranged between 3 and 11 in the studied participants. Population structure analysis revealed genetically distinct parasites in Côte d'Ivoire compared to samples from other countries. Exome capture identified protein-coding variants with ∼95% genotype concordance rate. INTERPRETATION We have generated resources to facilitate the development of molecular genetic tools that can estimate adult worm burdens and monitor parasite populations, thus providing essential information for the successful implementation of GPELF. FUNDING This work was financially supported by the Bill and Melinda Gates Foundation (https://www.gatesfoundation.org) under grant OPP1201530 (Co-PIs PUF & Gary J. Weil). B. malayi parasite material was generated with support of the Foundation for Barnes Jewish Hospital (PUF). In addition, the development of computational methods was supported by the National Institutes of Health under grants AI144161 (MM) and AI146353 (MM). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Affiliation(s)
- Young-Jun Choi
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kerstin Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Aboulaye Méité
- Programme National de la Lutte Contre la Schistosomiase, Les Geohelminthiases et la Filariose Lymphatique, Abidjan, Côte d'Ivoire
| | - Benjamin G Koudou
- Centre Suisse de Recherche Scientifique en Côte d'Ivoire, Abidjan, Côte d'Ivoire; Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - Peter U Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Makedonka Mitreva
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA; Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO, USA.
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Touloupou P, Fronterre C, Cano J, Prada JM, Smith M, Kontoroupis P, Brown P, Rivera RC, de Vlas SJ, Gunawardena S, Irvine MA, Njenga SM, Reimer L, Seife F, Sharma S, Michael E, Stolk WA, Pulan R, Spencer SEF, Hollingsworth TD. An Ensemble Framework for Projecting the Impact of Lymphatic Filariasis Interventions Across Sub-Saharan Africa at a Fine Spatial Scale. Clin Infect Dis 2024; 78:S108-S116. [PMID: 38662704 PMCID: PMC11045016 DOI: 10.1093/cid/ciae071] [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 Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as a public health problem by 2030. Although mass treatments have led to huge reductions in LF prevalence, some countries or regions may find it difficult to achieve elimination by 2030 owing to various factors, including local differences in transmission. Subnational projections of intervention impact are a useful tool in understanding these dynamics, but correctly characterizing their uncertainty is challenging. METHODS We developed a computationally feasible framework for providing subnational projections for LF across 44 sub-Saharan African countries using ensemble models, guided by historical control data, to allow assessment of the role of subnational heterogeneities in global goal achievement. Projected scenarios include ongoing annual treatment from 2018 to 2030, enhanced coverage, and biannual treatment. RESULTS Our projections suggest that progress is likely to continue well. However, highly endemic locations currently deploying strategies with the lower World Health Organization recommended coverage (65%) and frequency (annual) are expected to have slow decreases in prevalence. Increasing intervention frequency or coverage can accelerate progress by up to 5 or 6 years, respectively. CONCLUSIONS While projections based on baseline data have limitations, our methodological advancements provide assessments of potential bottlenecks for the global goals for LF arising from subnational heterogeneities. In particular, areas with high baseline prevalence may face challenges in achieving the 2030 goals, extending the "tail" of interventions. Enhancing intervention frequency and/or coverage will accelerate progress. Our approach facilitates preimplementation assessments of the impact of local interventions and is applicable to other regions and neglected tropical diseases.
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Affiliation(s)
| | | | - Jorge Cano
- Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN), WHO Regional Office for Africa, Brazzaville, Democratic Republic of the Congo
| | - Joaquin M Prada
- School of Veterinary Medicine, University of Surrey, Guildford, United Kingdom
| | - Morgan Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | | | - Paul Brown
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry, United Kingdom
| | - Rocio Caja Rivera
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, USA
| | - Sake J de Vlas
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | - Michael A Irvine
- Data and Analytic Services, British Columbia Centre for Disease Control, Vancouver, Canada
| | - Sammy M Njenga
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Lisa Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Fikre Seife
- Disease Prevention and Control Directorate, Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Swarnali Sharma
- Department of Mathematics, Vijaygarh Jyotish Ray College, Kolkata, India
| | - Edwin Michael
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, USA
| | - Wilma A Stolk
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Rachel Pulan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Simon E F Spencer
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry, United Kingdom
| | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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Prada JM, Touloupou P, Kebede B, Giorgi E, Sime H, Smith M, Kontoroupis P, Brown P, Cano J, Farkas H, Irvine M, Reimer L, Caja Rivera R, de Vlas SJ, Michael E, Stolk WA, Pulan R, Spencer SEF, Hollingsworth TD, Seife F. Subnational Projections of Lymphatic Filariasis Elimination Targets in Ethiopia to Support National Level Policy. Clin Infect Dis 2024; 78:S117-S125. [PMID: 38662702 PMCID: PMC11045027 DOI: 10.1093/cid/ciae072] [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 Lymphatic filariasis (LF) is a debilitating, poverty-promoting, neglected tropical disease (NTD) targeted for worldwide elimination as a public health problem (EPHP) by 2030. Evaluating progress towards this target for national programmes is challenging, due to differences in disease transmission and interventions at the subnational level. Mathematical models can help address these challenges by capturing spatial heterogeneities and evaluating progress towards LF elimination and how different interventions could be leveraged to achieve elimination by 2030. METHODS Here we used a novel approach to combine historical geo-spatial disease prevalence maps of LF in Ethiopia with 3 contemporary disease transmission models to project trends in infection under different intervention scenarios at subnational level. RESULTS Our findings show that local context, particularly the coverage of interventions, is an important determinant for the success of control and elimination programmes. Furthermore, although current strategies seem sufficient to achieve LF elimination by 2030, some areas may benefit from the implementation of alternative strategies, such as using enhanced coverage or increased frequency, to accelerate progress towards the 2030 targets. CONCLUSIONS The combination of geospatial disease prevalence maps of LF with transmission models and intervention histories enables the projection of trends in infection at the subnational level under different control scenarios in Ethiopia. This approach, which adapts transmission models to local settings, may be useful to inform the design of optimal interventions at the subnational level in other LF endemic regions.
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Affiliation(s)
- Joaquin M Prada
- Department of Comparative Biomedical Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | | | - Biruck Kebede
- RTI International, 3040 E Cornwallis Rd, Research Triangle Park, North Carolina 27709, USA
| | | | - Heven Sime
- Malaria and Neglected Tropical Diseases Research Team, Bacterial, Parasitic and Zoonotic Disease Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Morgan Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | | | - Paul Brown
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research, University of Warwick, Coventry, United Kingdom
| | - Jorge Cano
- Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN), WHO Regional Office for Africa, Brazzaville, Democratic Republic of the Congo
| | - Hajnal Farkas
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research, University of Warwick, Coventry, United Kingdom
| | - Mike Irvine
- Faculty of Science, BC Centre for Disease Control, Vancouver, Canada
| | - Lisa Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Rocio Caja Rivera
- College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Sake J de Vlas
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Edwin Michael
- College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Wilma A Stolk
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Rachel Pulan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Simon E F Spencer
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research, University of Warwick, Coventry, United Kingdom
| | - T Déirdre Hollingsworth
- Nuffield Department of Medicine, Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Fikre Seife
- Disease Prevention and Control Directorate, Federal Ministry of Health, Addis Ababa, Ethiopia
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Antony Oliver MC, Graham M, Gass KM, Medley GF, Clark J, Davis EL, Reimer LJ, King JD, Pouwels KB, Hollingsworth TD. Reducing the Antigen Prevalence Target Threshold for Stopping and Restarting Mass Drug Administration for Lymphatic Filariasis Elimination: A Model-Based Cost-effectiveness Simulation in Tanzania, India and Haiti. Clin Infect Dis 2024; 78:S160-S168. [PMID: 38662697 PMCID: PMC11045020 DOI: 10.1093/cid/ciae108] [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 Global Programme to Eliminate Lymphatic Filariasis (GPELF) aims to reduce and maintain infection levels through mass drug administration (MDA), but there is evidence of ongoing transmission after MDA in areas where Culex mosquitoes are the main transmission vector, suggesting that a more stringent criterion is required for MDA decision making in these settings. METHODS We use a transmission model to investigate how a lower prevalence threshold (<1% antigenemia [Ag] prevalence compared with <2% Ag prevalence) for MDA decision making would affect the probability of local elimination, health outcomes, the number of MDA rounds, including restarts, and program costs associated with MDA and surveys across different scenarios. To determine the cost-effectiveness of switching to a lower threshold, we simulated 65% and 80% MDA coverage of the total population for different willingness to pay per disability-adjusted life-year averted for India ($446.07), Tanzania ($389.83), and Haiti ($219.84). RESULTS Our results suggest that with a lower Ag threshold, there is a small proportion of simulations where extra rounds are required to reach the target, but this also reduces the need to restart MDA later in the program. For 80% coverage, the lower threshold is cost-effective across all baseline prevalences for India, Tanzania, and Haiti. For 65% MDA coverage, the lower threshold is not cost-effective due to additional MDA rounds, although it increases the probability of local elimination. Valuing the benefits of elimination to align with the GPELF goals, we find that a willingness to pay per capita government expenditure of approximately $1000-$4000 for 1% increase in the probability of local elimination would be required to make a lower threshold cost-effective. CONCLUSIONS Lower Ag thresholds for stopping MDAs generally mean a higher probability of local elimination, reducing long-term costs and health impacts. However, they may also lead to an increased number of MDA rounds required to reach the lower threshold and, therefore, increased short-term costs. Collectively, our analyses highlight that lower target Ag thresholds have the potential to assist programs in achieving lymphatic filariasis goals.
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Affiliation(s)
- Mary Chriselda Antony Oliver
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Matthew Graham
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Katherine M Gass
- Neglected Tropical Diseases Support Centre, The Task Force for Global Health, Decatur, Georgia, USA
| | - Graham F Medley
- Centre for Mathematical Modelling of Infectious Disease and Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Jessica Clark
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Emma L Davis
- Mathematics Institute and the Zeeman Institute for Systems Biology and Infectious Disease Epidemiological Research, University of Warwick, Coventry, United Kingdom
| | - Lisa J Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Jonathan D King
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Koen B Pouwels
- Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
| | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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Choi YJ, Fischer K, Méité A, Koudou BG, Fischer PU, Mitreva M. Distinguishing recrudescence from reinfection in lymphatic filariasis: a genomics-based approach for monitoring worm burden. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.11.05.23297155. [PMID: 37986785 PMCID: PMC10659506 DOI: 10.1101/2023.11.05.23297155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Background The Global Program to Eliminate Lymphatic Filariasis is the largest public health program based on mass drug administration (MDA). Despite decades of MDA, ongoing transmission in some countries remains a challenge. To optimize interventions, it is essential to differentiate between recrudescence (poor drug response and persistent infection) and new infections (ongoing transmission). Since adult filariae are inaccessible in humans, an approach that relies on genotyping the offspring microfilariae (mf) is required. Methods We utilized Brugia malayi adults and mf obtained from gerbils with a known pedigree to develop and validate our whole-genome amplification and kinship analysis approach. We then sequenced the genomes of Wuchereria bancrofti mf from infected humans from Côte d'Ivoire (CDI), characterized the population genetic diversity, and made inferences about the adult breeders. We developed a whole-exome capture panel for W. bancrofti to enrich parasite nuclear DNA from lower-quality samples contaminated with host DNA. Results We established a robust analysis pipeline using B. malayi adult and mf. We estimated the pre-treatment genetic diversity in W. bancrofti from 269 mf collected from 18 individuals, and further analyzed 1-year post-treatment samples of 74 mf from 4 individuals. By reconstructing and temporally tracking sibling relationships across pre- and post-treatment samples, we differentiated between new and established maternal families, suggesting reinfection in one subject and recrudescence in three subjects. Estimated reproductively active adult females ranged between 3 and 9 in the studied subjects. Hemizygosity of the male X-chromosome allowed for direct inference of haplotypes, facilitating robust maternal parentage inference, even when the genetic diversity was low. Population structure analysis revealed genetically distinct parasites among our CDI samples. Sequence composition and variant analysis of whole-exome libraries showed that the hybridization capture approach can effectively enrich parasite nuclear DNA and identify protein-coding variants with ∼95% genotype concordance rate. Conclusions We have generated resources to facilitate development of field-deployable genotyping tools that can estimate worm burdens and monitor parasite populations. These tools are essential for the success of lymphatic filariasis MDA programs. With further expansion of the databases to include geographically diverse samples, we will be able to spatially track parasite movement associated with host/vector migration.
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Crellen T, Haswell M, Sithithaworn P, Sayasone S, Odermatt P, Lamberton PHL, Spencer SEF, Déirdre Hollingsworth T. Diagnosis of helminths depends on worm fecundity and the distribution of parasites within hosts. Proc Biol Sci 2023; 290:20222204. [PMID: 36651047 PMCID: PMC9845982 DOI: 10.1098/rspb.2022.2204] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/16/2022] [Indexed: 01/19/2023] Open
Abstract
Helminth transmission and morbidity are dependent on the number of mature parasites within a host; however, observing adult worms is impossible for many natural infections. An outstanding challenge is therefore relating routine diagnostics, such as faecal egg counts, to the underlying worm burden. This relationship is complicated by density-dependent fecundity (egg output per worm reduces due to crowding at high burdens) and the skewed distribution of parasites (majority of helminths aggregated in a small fraction of hosts). We address these questions for the carcinogenic liver fluke Opisthorchis viverrini, which infects approximately 10 million people across Southeast Asia, by analysing five epidemiological surveys (n = 641) where adult flukes were recovered. Using a mechanistic model, we show that parasite fecundity varies between populations, with surveys from Thailand and Laos demonstrating distinct patterns of egg output and density-dependence. As the probability of observing faecal eggs increases with the number of mature parasites within a host, we quantify diagnostic sensitivity as a function of the worm burden and find that greater than 50% of cases are misdiagnosed as false negative in communities close to elimination. Finally, we demonstrate that the relationship between observed prevalence from routine diagnostics and true prevalence is nonlinear and strongly influenced by parasite aggregation.
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Affiliation(s)
- Thomas Crellen
- School of Biodiversity One Health and Veterinary Medicine, Graham Kerr Building, University of Glasgow, 82 Hillhead Street, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Melissa Haswell
- Office of the Deputy Vice Chancellor, Indigenous Strategy and Services and School of Geosciences, John Woolley Building, University of Sydney, Sydney, New South Wales 2050, Australia
- School of Public Health and Social Work, Kelvin Grove Campus, Queensland University of Technology, Brisbane City, Queensland 4000, Australia
| | - Paiboon Sithithaworn
- Department of Parasitology, Khon Kaen University, 123 Thanon Mittraphap, Khon Kaen 40002, Thailand
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Samsenthai Road, Sisattanak district, Vientiane, Lao PDR
| | - Peter Odermatt
- Department of Public Health and Epidemiology, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil 4123, Switzerland
- University of Basel, Petersplatz 1, Basel 4001, Switzerland
| | - Poppy H. L. Lamberton
- School of Biodiversity One Health and Veterinary Medicine, Graham Kerr Building, University of Glasgow, 82 Hillhead Street, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | | | - T. Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
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Stolk WA, Coffeng LE, Bolay FK, Eneanya OA, Fischer PU, Hollingsworth TD, Koudou BG, Méité A, Michael E, Prada JM, Caja Rivera RM, Sharma S, Touloupou P, Weil GJ, de Vlas SJ. Comparing antigenaemia- and microfilaraemia as criteria for stopping decisions in lymphatic filariasis elimination programmes in Africa. PLoS Negl Trop Dis 2022; 16:e0010953. [PMID: 36508458 PMCID: PMC9779720 DOI: 10.1371/journal.pntd.0010953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 12/22/2022] [Accepted: 11/14/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Mass drug administration (MDA) is the main strategy towards lymphatic filariasis (LF) elimination. Progress is monitored by assessing microfilaraemia (Mf) or circulating filarial antigenaemia (CFA) prevalence, the latter being more practical for field surveys. The current criterion for stopping MDA requires <2% CFA prevalence in 6- to 7-year olds, but this criterion is not evidence-based. We used mathematical modelling to investigate the validity of different thresholds regarding testing method and age group for African MDA programmes using ivermectin plus albendazole. METHODOLGY/PRINCIPAL FINDINGS We verified that our model captures observed patterns in Mf and CFA prevalence during annual MDA, assuming that CFA tests are positive if at least one adult worm is present. We then assessed how well elimination can be predicted from CFA prevalence in 6-7-year-old children or from Mf or CFA prevalence in the 5+ or 15+ population, and determined safe (>95% positive predictive value) thresholds for stopping MDA. The model captured trends in Mf and CFA prevalences reasonably well. Elimination cannot be predicted with sufficient certainty from CFA prevalence in 6-7-year olds. Resurgence may still occur if all children are antigen-negative, irrespective of the number tested. Mf-based criteria also show unfavourable results (PPV <95% or unpractically low threshold). CFA prevalences in the 5+ or 15+ population are the best predictors, and post-MDA threshold values for stopping MDA can be as high as 10% for 15+. These thresholds are robust for various alternative assumptions regarding baseline endemicity, biological parameters and sampling strategies. CONCLUSIONS/SIGNIFICANCE For African areas with moderate to high pre-treatment Mf prevalence that have had 6 or more rounds of annual ivermectin/albendazole MDA with adequate coverage, we recommend to adopt a CFA threshold prevalence of 10% in adults (15+) for stopping MDA. This could be combined with Mf testing of CFA positives to ensure absence of a significant Mf reservoir for transmission.
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Affiliation(s)
- Wilma A. Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- * E-mail:
| | - Luc E. Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Fatorma K. Bolay
- National Public Health Institute of Liberia (NPHIL), Monrovia, Liberia
| | - Obiora A. Eneanya
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Peter U. Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - T. Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Benjamin G. Koudou
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Abidjan, Côte d’Ivoire
- Laboratoire de Cytologie et Biologie Animale, UFR Science de la Nature, Université Nangui Abrogoua Abidjan, Abidjan, Côte d’Ivoire
| | - Aboulaye Méité
- Programme National de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive, Abidjan, Côte d’Ivoire
| | - Edwin Michael
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Rocio M. Caja Rivera
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Swarnali Sharma
- Department of Biological Sciences, University of Notre Dame, South Bend, Indiana, United States of America
- Christian Medical College, IDA Scudder Rd, Vellore, Tamil Nadu, India
| | - Panayiota Touloupou
- Department of Statistics, University of Warwick, Coventry, United Kingdom
- School of Mathematics, University of Birmingham, Birmingham, United Kingdom
| | - Gary J. Weil
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sake J. de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Eneanya OA, Gankpala L, Goss CW, Momolu AT, Nyan ES, Gray EB, Fischer K, Curtis K, Bolay FK, Weil GJ, Fischer PU. Community-based trial assessing the impact of annual versus semiannual mass drug administration with ivermectin plus albendazole and praziquantel on helminth infections in northwestern Liberia. Acta Trop 2022; 231:106437. [PMID: 35405102 PMCID: PMC9168441 DOI: 10.1016/j.actatropica.2022.106437] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/10/2022] [Accepted: 03/28/2022] [Indexed: 11/30/2022]
Abstract
Mass drug administration (MDA) with ivermectin plus albendazole was more effective for clearing bancroftian filariasis than it was for onchocerciasis or hookworm. Semiannual MDA was no more effective than annual MDA for reducing prevalences of W. bancrofti, O. volvulus, or hookworm infections. Decreases in bancroftian filariasis prevalence were achieved despite unavoidable interruptions in our study related to the 2014 West Africa Ebola epidemic and the 2020 SARS-CoV-2 pandemic. Neglected Tropical Disease elimination programs in areas coendemic for lymphatic filariasis and onchocerciasis should focus on delivering high quality annual MDA with high coverage and compliance and not try to stretch limited resources to deliver semiannual MDA. MDA with praziquantel had little impact on Schistosoma mansoni infection in the heavily infected area.
We assessed the impact of three annual vs five semiannual rounds of mass drug administration (MDA) with ivermectin plus albendazole followed by praziquantel for the control or elimination of lymphatic filariasis (LF), onchocerciasis, soil-transmitted helminth (STH) infections and schistosomiasis in Lofa County, Liberia. The study started in 2012 and was interrupted in 2014 during the Ebola virus outbreak. Repeated cross-sectional surveys were conducted in individuals 5 years and older to measure infection markers. Wuchereria bancrofti antigenemia prevalences decreased from 12.5 to 1.2% (90% reduction) and from 13.6 to 4.2% (69% reduction) one year after three rounds of annual or five rounds of semiannual MDA, respectively. Mixed effects logistic regression models showed decreases in odds of antigenemia positivity were 91 and 74% at that time in the annual and semiannual treatment zones, respectively (p < 0.001). Semiannual MDA was slightly more effective for reducing Onchocerca volvulus microfiladermia prevalence and at follow-up 3 were 74% (from 14.4 to 3.7%) and 83% (from 23.6 to 4.5%) in the annual and semiannual treatment zones, respectively. Both treatment schedules had similar beneficial effects on hookworm prevalence. Thus, annual and semiannual MDA with ivermectin and albendazole had similar beneficial impacts on LF, onchocerciasis, and STH in this setting. In contrast, MDA with praziquantel had little impact on hyperendemic Schistosoma mansoni in the study area. Results from a long-term follow-up survey showed that improvements in infection parameters were sustained by routine annual MDA provided by the Liberian Ministry of Health after our study endpoint.
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Affiliation(s)
- Obiora A Eneanya
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Lincoln Gankpala
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Charles W Goss
- Division of Biostatistics, Washington University School of Medicine, St. Louis, MO, United States
| | - Aaron T Momolu
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Enoch S Nyan
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Emmanuel B Gray
- Ministry of Health of Liberia, C.B. Dunbar Hospital, Gbarnga, Liberia
| | - Kerstin Fischer
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Kurt Curtis
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Fatorma K Bolay
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Gary J Weil
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Peter U Fischer
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States.
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9
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Okoyo C, Onyango N, Orowe I, Mwandawiro C, Medley G. Sensitivity Analysis of a Transmission Interruption Model for the Soil-Transmitted Helminth Infections in Kenya. Front Public Health 2022; 10:841883. [PMID: 35400031 PMCID: PMC8990131 DOI: 10.3389/fpubh.2022.841883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/28/2022] [Indexed: 12/03/2022] Open
Abstract
As the world rallies toward the endgame of soil-transmitted helminths (STH) elimination by the year 2030, there is a need for efficient and robust mathematical models that would enable STH programme managers to target the scarce resources and interventions, increase treatment coverage among specific sub-groups of the population, and develop reliable surveillance systems that meet sensitivity and specificity requirements for the endgame of STH elimination. However, the considerable complexities often associated with STH-transmission models underpin the need for specifying a large number of parameters and inputs, which are often available with considerable degree of uncertainty. Additionally, the model may behave counter-intuitive especially when there are non-linearities in multiple input-output relationships. In this study, we performed a global sensitivity analysis (GSA), based on a variance decomposition method: extended Fourier Amplitude Sensitivity Test (eFAST), to a recently developed STH-transmission model in Kenya (an STH endemic country) to; (1) robustly compute sensitivity index (SI) for each parameter, (2) rank the parameters in order of their importance (from most to least influential), and (3) quantify the influence of each parameter, singly and cumulatively, on the model output. The sensitivity analysis (SA) results demonstrated that the model outcome (STH worm burden elimination in the human host) was significantly sensitive to some key parameter groupings: combined effect of improved water source and sanitation (ϕ), rounds of treatment offered (τ), efficacy of the drug used during treatment (h), proportion of the adult population treated (ga: akin to community-wide treatment), mortality rate of the mature worms in the human host (μ), and the strength of the -dependence of worm egg production (γ). For STH control programmes to effectively reach the endgame (STH elimination in the entire community), these key parameter groupings need to be targeted since together they contribute to a strategic public health intervention.
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Affiliation(s)
- Collins Okoyo
- Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
- School of Mathematics, University of Nairobi, Nairobi, Kenya
- *Correspondence: Collins Okoyo
| | - Nelson Onyango
- School of Mathematics, University of Nairobi, Nairobi, Kenya
| | - Idah Orowe
- School of Mathematics, University of Nairobi, Nairobi, Kenya
| | - Charles Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Graham Medley
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine (LSHTM), London, United Kingdom
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Burgert-Brucker CR, Zoerhoff KL, Headland M, Shoemaker EA, Stelmach R, Karim MJ, Batcho W, Bougouma C, Bougma R, Benjamin Didier B, Georges N, Marfo B, Lemoine JF, Pangaribuan HU, Wijayanti E, Coulibaly YI, Doumbia SS, Rimal P, Salissou AB, Bah Y, Mwingira U, Nshala A, Muheki E, Shott J, Yevstigneyeva V, Ndayishimye E, Baker M, Kraemer J, Brady M. Risk factors associated with failing pre-transmission assessment surveys (pre-TAS) in lymphatic filariasis elimination programs: Results of a multi-country analysis. PLoS Negl Trop Dis 2020; 14:e0008301. [PMID: 32479495 PMCID: PMC7289444 DOI: 10.1371/journal.pntd.0008301] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 06/11/2020] [Accepted: 04/16/2020] [Indexed: 11/20/2022] Open
Abstract
Achieving elimination of lymphatic filariasis (LF) as a public health problem requires a minimum of five effective rounds of mass drug administration (MDA) and demonstrating low prevalence in subsequent assessments. The first assessments recommended by the World Health Organization (WHO) are sentinel and spot-check sites-referred to as pre-transmission assessment surveys (pre-TAS)-in each implementation unit after MDA. If pre-TAS shows that prevalence in each site has been lowered to less than 1% microfilaremia or less than 2% antigenemia, the implementation unit conducts a TAS to determine whether MDA can be stopped. Failure to pass pre-TAS means that further rounds of MDA are required. This study aims to understand factors influencing pre-TAS results using existing programmatic data from 554 implementation units, of which 74 (13%) failed, in 13 countries. Secondary data analysis was completed using existing data from Bangladesh, Benin, Burkina Faso, Cameroon, Ghana, Haiti, Indonesia, Mali, Nepal, Niger, Sierra Leone, Tanzania, and Uganda. Additional covariate data were obtained from spatial raster data sets. Bivariate analysis and multilinear regression were performed to establish potential relationships between variables and the pre-TAS result. Higher baseline prevalence and lower elevation were significant in the regression model. Variables statistically significantly associated with failure (p-value ≤0.05) in the bivariate analyses included baseline prevalence at or above 5% or 10%, use of Filariasis Test Strips (FTS), primary vector of Culex, treatment with diethylcarbamazine-albendazole, higher elevation, higher population density, higher enhanced vegetation index (EVI), higher annual rainfall, and 6 or more rounds of MDA. This paper reports for the first time factors associated with pre-TAS results from a multi-country analysis. This information can help countries more effectively forecast program activities, such as the potential need for more rounds of MDA, and prioritize resources to ensure adequate coverage of all persons in areas at highest risk of failing pre-TAS.
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Affiliation(s)
| | - Kathryn L. Zoerhoff
- Global Health Division, RTI International, Washington, DC, United States of America
| | - Maureen Headland
- Global Health Division, RTI International, Washington, DC, United States of America
- Global Health, Population, and Nutrition, FHI 360, Washington, DC, United States of America
| | - Erica A. Shoemaker
- Global Health Division, RTI International, Washington, DC, United States of America
| | - Rachel Stelmach
- Global Health Division, RTI International, Washington, DC, United States of America
| | | | - Wilfrid Batcho
- National Control Program of Communicable Diseases, Ministry of Health, Cotonou, Benin
| | - Clarisse Bougouma
- Lymphatic Filariasis Elimination Program, Ministère de la Santé, Ouagadougou, Burkina Faso
| | - Roland Bougma
- Lymphatic Filariasis Elimination Program, Ministère de la Santé, Ouagadougou, Burkina Faso
| | - Biholong Benjamin Didier
- National Onchocerciasis and Lymphatic Filariasis Control Program, Ministry of Health, Yaounde, Cameroon
| | - Nko'Ayissi Georges
- National Onchocerciasis and Lymphatic Filariasis Control Program, Ministry of Health, Yaounde, Cameroon
| | - Benjamin Marfo
- Neglected Tropical Diseases Programme, Ghana Health Service, Accra, Ghana
| | | | | | - Eksi Wijayanti
- National Institute Health Research & Development, Ministry of Health, Jakarta, Indonesia
| | - Yaya Ibrahim Coulibaly
- Filariasis Unit, International Center of Excellence in Research, Faculty of Medicine and Odontostomatology, Bamako, Mali
| | - Salif Seriba Doumbia
- Filariasis Unit, International Center of Excellence in Research, Faculty of Medicine and Odontostomatology, Bamako, Mali
| | - Pradip Rimal
- Epidemiology and Disease Control Division, Department of Health Service, Kathmandu, Nepal
| | | | - Yukaba Bah
- National Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Upendo Mwingira
- Neglected Tropical Disease Control Programme, National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Andreas Nshala
- IMA World Health/Tanzania NTD Control Programme, Uppsala University, & TIBA Fellow, Dar es Salaam, Tanzania
| | - Edridah Muheki
- Programme to Eliminate Lymphatic Filariasis, Ministry of Health, Kampala, Uganda
| | - Joseph Shott
- Division of Neglected Tropical Diseases, Office of Infectious Diseases, Bureau for Global Health, USAID, Washington, DC, United States of America
| | - Violetta Yevstigneyeva
- Division of Neglected Tropical Diseases, Office of Infectious Diseases, Bureau for Global Health, USAID, Washington, DC, United States of America
| | - Egide Ndayishimye
- Global Health, Population, and Nutrition, FHI 360, Washington, DC, United States of America
| | - Margaret Baker
- Global Health Division, RTI International, Washington, DC, United States of America
| | - John Kraemer
- Global Health Division, RTI International, Washington, DC, United States of America
- Georgetown University, Washington, DC, United States of America
| | - Molly Brady
- Global Health Division, RTI International, Washington, DC, United States of America
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11
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Amoah B, Diggle PJ, Giorgi E. A geostatistical framework for combining spatially referenced disease prevalence data from multiple diagnostics. Biometrics 2019; 76:158-170. [PMID: 31449327 DOI: 10.1111/biom.13142] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/06/2019] [Indexed: 11/30/2022]
Abstract
Multiple diagnostic tests are often used due to limited resources or because they provide complementary information on the epidemiology of a disease under investigation. Existing statistical methods to combine prevalence data from multiple diagnostics ignore the potential overdispersion induced by the spatial correlations in the data. To address this issue, we develop a geostatistical framework that allows for joint modelling of data from multiple diagnostics by considering two main classes of inferential problems: (a) to predict prevalence for a gold-standard diagnostic using low-cost and potentially biased alternative tests; (b) to carry out joint prediction of prevalence from multiple tests. We apply the proposed framework to two case studies: mapping Loa loa prevalence in Central and West Africa, using miscroscopy, and a questionnaire-based test called RAPLOA; mapping Plasmodium falciparum malaria prevalence in the highlands of Western Kenya using polymerase chain reaction and a rapid diagnostic test. We also develop a Monte Carlo procedure based on the variogram in order to identify parsimonious geostatistical models that are compatible with the data. Our study highlights (a) the importance of accounting for diagnostic-specific residual spatial variation and (b) the benefits accrued from joint geostatistical modelling so as to deliver more reliable and precise inferences on disease prevalence.
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Affiliation(s)
- Benjamin Amoah
- CHICAS, Lancaster University Medical School, Lancaster, UK
| | - Peter J Diggle
- CHICAS, Lancaster University Medical School, Lancaster, UK
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12
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Eneanya OA, Fronterre C, Anagbogu I, Okoronkwo C, Garske T, Cano J, Donnelly CA. Mapping the baseline prevalence of lymphatic filariasis across Nigeria. Parasit Vectors 2019; 12:440. [PMID: 31522689 PMCID: PMC6745770 DOI: 10.1186/s13071-019-3682-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/22/2019] [Indexed: 11/30/2022] Open
Abstract
Introduction The baseline endemicity profile of lymphatic filariasis (LF) is a key benchmark for planning control programmes, monitoring their impact on transmission and assessing the feasibility of achieving elimination. Presented in this work is the modelled serological and parasitological prevalence of LF prior to the scale-up of mass drug administration (MDA) in Nigeria using a machine learning based approach. Methods LF prevalence data generated by the Nigeria Lymphatic Filariasis Control Programme during country-wide mapping surveys conducted between 2000 and 2013 were used to build the models. The dataset comprised of 1103 community-level surveys based on the detection of filarial antigenemia using rapid immunochromatographic card tests (ICT) and 184 prevalence surveys testing for the presence of microfilaria (Mf) in blood. Using a suite of climate and environmental continuous gridded variables and compiled site-level prevalence data, a quantile regression forest (QRF) model was fitted for both antigenemia and microfilaraemia LF prevalence. Model predictions were projected across a continuous 5 × 5 km gridded map of Nigeria. The number of individuals potentially infected by LF prior to MDA interventions was subsequently estimated. Results Maps presented predict a heterogeneous distribution of LF antigenemia and microfilaraemia in Nigeria. The North-Central, North-West, and South-East regions displayed the highest predicted LF seroprevalence, whereas predicted Mf prevalence was highest in the southern regions. Overall, 8.7 million and 3.3 million infections were predicted for ICT and Mf, respectively. Conclusions QRF is a machine learning-based algorithm capable of handling high-dimensional data and fitting complex relationships between response and predictor variables. Our models provide a benchmark through which the progress of ongoing LF control efforts can be monitored.
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Affiliation(s)
- Obiora A Eneanya
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Claudio Fronterre
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | | | | | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jorge Cano
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Christl A Donnelly
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.,Department of Statistics, University of Oxford, Oxford, UK
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13
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The roadmap towards elimination of lymphatic filariasis by 2030: insights from quantitative and mathematical modelling. Gates Open Res 2019; 3:1538. [PMID: 31728440 PMCID: PMC6833911 DOI: 10.12688/gatesopenres.13065.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2019] [Indexed: 01/26/2023] Open
Abstract
The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 to eliminate lymphatic filariasis (LF) as a public health problem by 1) interrupting transmission through mass drug administration (MDA) and 2) offering basic care to those suffering from lymphoedema or hydrocele due to the infection. Although impressive progress has been made, the initial target year of 2020 will not be met everywhere. The World Health Organization recently proposed 2030 as the new target year for elimination of lymphatic filariasis (LF) as a public health problem. In this letter, LF modelers of the Neglected Tropical Diseases (NTDs) Modelling Consortium reflect on the proposed targets for 2030 from a quantitative perspective. While elimination as a public health problem seems technically and operationally feasible, it is uncertain whether this will eventually also lead to complete elimination of transmission. The risk of resurgence needs to be mitigated by strong surveillance after stopping interventions and sometimes perhaps additional interventions.
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14
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Berg Soto A, Xu Z, Wood P, Sanuku N, Robinson LJ, King CL, Tisch D, Susapu M, Graves PM. Combining different diagnostic studies of lymphatic filariasis for risk mapping in Papua New Guinea: a predictive model from microfilaraemia and antigenaemia prevalence surveys. Trop Med Health 2018; 46:41. [PMID: 30533996 PMCID: PMC6280391 DOI: 10.1186/s41182-018-0123-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/13/2018] [Indexed: 01/30/2023] Open
Abstract
Background The Global Programme to Eliminate Lymphatic Filariasis has encouraged countries to follow a set of guidelines to help them assess the need for mass drug administration and evaluate its progress. Papua New Guinea (PNG) is one of the highest priority countries in the Western Pacific for lymphatic filariasis and the site of extensive research on lymphatic filariasis and surveys of its prevalence. However, different diagnostic tests have been used and thresholds for each test are unclear. Methods We reviewed the prevalence of lymphatic filariasis reported in 295 surveys conducted in PNG between 1990 and 2014, of which 65 used more than one test. Results from different diagnostics were standardised using a set of criteria that included a model to predict antigen prevalence from microfilariae prevalence. We mapped the point location of each of these surveys and categorised their standardised prevalence estimates. Results Several predictive models were produced and investigated, including the effect of any mass drug administration and number of rounds prior to the surveys. One model was chosen based on goodness of fit parameters and used to predict antigen prevalence for surveys that tested only for microfilariae. Standardised prevalence values show that 72% of all surveys reported a prevalence above 0.05. High prevalence was situated on the coastal north, south and island regions, while the central highland area of Papua New Guinea shows low levels of prevalence. Conclusions Our study is the first to provide an explicit predictive relationship between the prevalence values based on empirical results from antigen and microfilaria tests, taking into account the occurrence of mass drug administration. This is a crucial step to combine studies to develop risk maps of lymphatic filariasis for programme planning and evaluation, as shown in the case of Papua New Guinea. Electronic supplementary material The online version of this article (10.1186/s41182-018-0123-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alvaro Berg Soto
- 1Information Resources, James Cook University, Townsville, QLD 4811 Australia
| | - Zhijing Xu
- 2Research School of Population Health, Australian National University, Canberra, ACT 2601 Australia
| | - Peter Wood
- 3College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD 4870 Australia
| | - Nelly Sanuku
- 4Vector Borne Diseases Unit, PNG Institute of Medical Research, Goroka, Papua New Guinea
| | - Leanne J Robinson
- 4Vector Borne Diseases Unit, PNG Institute of Medical Research, Goroka, Papua New Guinea.,5Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004 Australia
| | - Christopher L King
- 6School of Medicine and Veterans Affairs Administration, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Daniel Tisch
- 7Department of Population and Quantitative Health Science, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Melinda Susapu
- Malaria and Vector Borne Diseases, Public Health, Department of Health, Port Moresby, Papua New Guinea
| | - Patricia M Graves
- 3College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD 4870 Australia
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Michael E, Smith ME, Katabarwa MN, Byamukama E, Griswold E, Habomugisha P, Lakwo T, Tukahebwa E, Miri ES, Eigege A, Ngige E, Unnasch TR, Richards FO. Substantiating freedom from parasitic infection by combining transmission model predictions with disease surveys. Nat Commun 2018; 9:4324. [PMID: 30337529 PMCID: PMC6193962 DOI: 10.1038/s41467-018-06657-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 09/14/2018] [Indexed: 11/22/2022] Open
Abstract
Stopping interventions is a critical decision for parasite elimination programmes. Quantifying the probability that elimination has occurred due to interventions can be facilitated by combining infection status information from parasitological surveys with extinction thresholds predicted by parasite transmission models. Here we demonstrate how the integrated use of these two pieces of information derived from infection monitoring data can be used to develop an analytic framework for guiding the making of defensible decisions to stop interventions. We present a computational tool to perform these probability calculations and demonstrate its practical utility for supporting intervention cessation decisions by applying the framework to infection data from programmes aiming to eliminate onchocerciasis and lymphatic filariasis in Uganda and Nigeria, respectively. We highlight a possible method for validating the results in the field, and discuss further refinements and extensions required to deploy this predictive tool for guiding decision making by programme managers. The decision when to stop an intervention is a critical component of parasite elimination programmes, but reliance on surveillance data alone can be inaccurate. Here, Michael et al. combine parasite transmission model predictions with disease survey data to more reliably determine when interventions can be stopped.
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Affiliation(s)
- Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.
| | - Morgan E Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Moses N Katabarwa
- Emory University and The Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA, 30307, USA
| | | | - Emily Griswold
- Emory University and The Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA, 30307, USA
| | | | - Thomson Lakwo
- Vector Control Division, Ministry of Health, 15 Bombo Road, P.O. Box 1661, Kampala, Uganda
| | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health, 15 Bombo Road, P.O. Box 1661, Kampala, Uganda
| | - Emmanuel S Miri
- The Carter Center, Nigeria, 1 Jeka Kadima Street off Tudun Wada Ring Road, Jos, Nigeria
| | - Abel Eigege
- The Carter Center, Nigeria, 1 Jeka Kadima Street off Tudun Wada Ring Road, Jos, Nigeria
| | - Evelyn Ngige
- Federal Ministry of Health, Federal Sceretariat, Garki-Abuja, Nigeria
| | - Thomas R Unnasch
- Global Health Infectious Disease Research, College of Public Health, University of South Florida, 33620, Tampa, FL, USA
| | - Frank O Richards
- Emory University and The Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA, 30307, USA
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Prada JM, Touloupou P, Adriko M, Tukahebwa EM, Lamberton PHL, Hollingsworth TD. Understanding the relationship between egg- and antigen-based diagnostics of Schistosoma mansoni infection pre- and post-treatment in Uganda. Parasit Vectors 2018; 11:21. [PMID: 29310695 PMCID: PMC5759883 DOI: 10.1186/s13071-017-2580-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/06/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Schistosomiasis is a major socio-economic and public health problem in many sub-Saharan African countries. After large mass drug administration (MDA) campaigns, prevalence of infection rapidly returns to pre-treatment levels. The traditional egg-based diagnostic for schistosome infections, Kato-Katz, is being substituted in many settings by circulating antigen recognition-based diagnostics, usually the point-of-care circulating cathodic antigen test (CCA). The relationship between these diagnostics is poorly understood, particularly after treatment in both drug-efficacy studies and routine monitoring. RESULTS We created a model of schistosome infections to better understand and quantify the relationship between these two egg- and adult worm antigen-based diagnostics. We focused particularly on the interpretation of "trace" results after CCA testing. Our analyses suggest that CCA is generally a better predictor of prevalence, particularly after treatment, and that trace CCA results are typically associated with truly infected individuals. CONCLUSIONS Even though prevalence rises to pre-treatment levels only six months after MDAs, our model suggests that the average intensity of infection is much lower, and is probably in part due to a small burden of surviving juveniles from when the treatment occurred. This work helps to better understand CCA diagnostics and the interpretation of post-treatment prevalence estimations.
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Affiliation(s)
- Joaquín M. Prada
- Department of Mathematics, University of Warwick, Coventry, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | | | - Moses Adriko
- Vector Control Division, Ministry of Health, Uganda, Kampala, Uganda
| | | | - Poppy H. L. Lamberton
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
- Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow, UK
| | - T. Déirdre Hollingsworth
- Department of Mathematics, University of Warwick, Coventry, UK
- Big Data Institute, University of Oxford, Oxford, UK
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