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Mwasunda JA, Irunde JI, Stephano MA, Chacha CS. Fish-borne parasitic zoonoses transmission dynamics: The case of anisakiasis. INFORMATICS IN MEDICINE UNLOCKED 2023. [DOI: 10.1016/j.imu.2023.101205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023] Open
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Bonnet G, Pizzitutti F, Gonzales-Gustavson EA, Gabriël S, Pan WK, Garcia HH, Bustos JA, Vilchez P, O’Neal SE. CystiHuman: A model of human neurocysticercosis. PLoS Comput Biol 2022; 18:e1010118. [PMID: 35587497 PMCID: PMC9159625 DOI: 10.1371/journal.pcbi.1010118] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 06/01/2022] [Accepted: 04/19/2022] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION The Taenia solium tapeworm is responsible for cysticercosis, a neglected tropical disease presenting as larvae in the body of a host following taenia egg ingestion. Neurocysticercosis (NCC), the name of the disease when it affects the human central nervous system, is a major cause of epilepsy in developing countries, and can also cause intracranial hypertension, hydrocephalus and death. Simulation models can help identify the most cost-effective interventions before their implementation. Modelling NCC should enable the comparison of a broad range of interventions, from treatment of human taeniasis (presence of an adult taenia worm in the human intestine) to NCC mitigation. It also allows a focus on the actual impact of the disease, rather than using proxies as is the case for other models. METHODS This agent-based model is the first model that simulates human NCC and associated pathologies. It uses the output of another model, CystiAgent, which simulates the evolution of pig cysticercosis and human taeniasis, adding human and cyst agents, including a model of cyst location and stage, human symptoms, and treatment. CystiHuman also accounts for delays in the appearance of NCC-related symptoms. It comprises three modules detailing cyst development, seizure probability and timing, and intracranial hypertension/hydrocephalus, respectively. It has been implemented in Java MASON and calibrated in three endemic villages in Peru, then applied to another village (Rica Playa) to compare simulation results with field data in that village. RESULTS AND DISCUSSION Despite limitations in available field data, parameter values found through calibration are plausible and simulated outcomes in Rica Playa are close to actual values for NCC prevalence and the way it increases with age and cases with single lesions. Initial simulations further suggest that short-term interventions followed by a rapid increase in taeniasis prevalence back to original levels may have limited impacts on NCC prevalence.
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Affiliation(s)
- Gabrielle Bonnet
- Independent Consultant for the School of Public Health, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Francesco Pizzitutti
- Independent Consultant for the School of Public Health, Oregon Health & Science University, Portland, Oregon, United States of America
| | | | - Sarah Gabriël
- Department of Veterinary Public Health and Food Safety, Ghent University, Gent, Belgium
| | - William K. Pan
- Nicholas School of Environment and Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
| | - Hector H. Garcia
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Lima, Peru
- Cysticercosis Unit, National Institute of Neurological Sciences, Lima, Peru
| | - Javier A. Bustos
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Percy Vilchez
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Seth E. O’Neal
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Lima, Peru
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
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Andrade-Mogrovejo DA, Gonzales-Gustavson E, Ho-Palma AC, Prada JM, Bonnet G, Pizzitutti F, Gomez-Puerta LA, Arroyo G, O’Neal SE, Garcia HH, Guitian J, Gonzalez A. Development of a dose-response model for porcine cysticercosis. PLoS One 2022; 17:e0264898. [PMID: 35286329 PMCID: PMC8920259 DOI: 10.1371/journal.pone.0264898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 02/21/2022] [Indexed: 01/11/2023] Open
Abstract
Taenia solium is an important cause of acquired epilepsy worldwide and remains endemic in Asia, Africa, and Latin America. Transmission of this parasite is still poorly understood despite the design of infection experiments to improve our knowledge of the disease, with estimates for critical epidemiological parameters, such as the probability of human-to-pig infection after exposure to eggs, still lacking. In this paper, a systematic review was carried out and eight pig infection experiments were analyzed to describe the probability of developing cysts. These experiments included different pathways of inoculation: with ingestion of proglottids, eggs, and beetles that ingested eggs, and direct injection of activated oncospheres into the carotid artery. In these experiments, different infective doses were used, and the numbers of viable and degenerated cysts in the body and brain of each pig were registered. Five alternative dose-response models (exponential, logistic, log-logistic, and exact and approximate beta-Poisson) were assessed for their accuracy in describing the observed probabilities of cyst development as a function of the inoculation dose. Dose-response models were developed separately for the presence of three types of cysts (any, viable only, and cysts in the brain) and considered for each of the four inoculation methods ("Proglottids", "Eggs", "Beetles" and "Carotid"). The exact beta-Poisson model best fit the data for the three types of cysts and all relevant exposure pathways. However, observations for some exposure pathways were too scarce to reliably define a dose-response curve with any model. A wide enough range of doses and sufficient sample sizes was only found for the "Eggs" pathway and a merged "Oral" pathway combining the "Proglottids", "Eggs" and "Beetles" pathways. Estimated parameter values from this model suggest that a low infective dose is sufficient to result in a 50% probability for the development of any cyst or for viable cyst infections. Although this is a preliminary model reliant on a limited dataset, the parameters described in this manuscript should contribute to the design of future experimental infections related to T. solium transmission, as well as the parameterization of simulation models of transmission aimed at informing control.
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Affiliation(s)
- Daniel A. Andrade-Mogrovejo
- Department of Animal and Public Health, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Eloy Gonzales-Gustavson
- Department of Animal and Public Health, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
- Tropical and Highlands Veterinary Research Institute, Universidad Nacional Mayor de San Marcos, Lima, Peru
- * E-mail:
| | - Ana C. Ho-Palma
- Department of Human Medicine, School of Human Medicine, Universidad Nacional del Centro del Perú, Huancayo, Peru
| | - Joaquín M. Prada
- Department of Veterinary Epidemiology and Public Health, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Gabrielle Bonnet
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Francesco Pizzitutti
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Luis A. Gomez-Puerta
- Department of Animal and Public Health, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Gianfranco Arroyo
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, San Martín de Porres, Peru
| | - Seth E. O’Neal
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, San Martín de Porres, Peru
| | - Hector H. Garcia
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, San Martín de Porres, Peru
- Cysticercosis Unit, National Institute of Neurological Sciences, Lima, Peru
| | - Javier Guitian
- Veterinary Epidemiology, Economics and Public Health Group, Department of Pathobiology and Population Sciences, The Royal Veterinary College, Hertfordshire, United Kingdom
| | - Armando Gonzalez
- Department of Animal and Public Health, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
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Mwasunda JA, Irunde JI, Kajunguri D, Kuznetsov D. Optimal control analysis of Taenia saginata bovine cysticercosis and human taeniasis. Parasite Epidemiol Control 2022; 16:e00236. [PMID: 35028439 PMCID: PMC8741606 DOI: 10.1016/j.parepi.2021.e00236] [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: 10/06/2021] [Revised: 12/09/2021] [Accepted: 12/27/2021] [Indexed: 11/29/2022] Open
Abstract
Bovine cysticercosis and human taeniasis are neglected food-borne diseases that pose challenge to food safety, human health and livelihood of rural livestock farmers. In this paper, we have formulated and analyzed a deterministic model for transmission dynamics and control of taeniasis and cysticercosis in humans and cattle respectively. The analysis shows that both the disease free equilibrium (DFE) and endemic equilibrium (EE) exist. To study the dynamics of the diseases, we derived the basic reproduction number R 0 by next generation matrix method which shows whether the diseases die or persist in humans and cattle. The diseases clear if R 0 < 1 and persist when R 0 > 1. The normalized forward sensitivity index is used to derive sensitive indices of model parameters. Sensitivity analysis results indicate that human's and cattle's recruitment rates, infection rate of cattle from contaminated environment, probability of humans to acquire taeniasis due to consumption of infected meat, defecation rate of humans with taeniasis and the consumption rate of raw or undercooked infected meat are the most positive sensitive parameters whereas the natural death rates for humans, cattle, Taenia saginata eggs and the proportion of unconsumed infected meat are the most negative sensitive parameters in diseases' transmission. These results suggest that control measures such as improving meat cooking, meat inspection and treatment of infected humans will be effective for controlling taeniasis and cysticercosis in humans and cattle respectively. The optimal control theory is applied by considering three time dependent controls which are improved meat cooking, vaccination of cattle, and treatment of humans with taeniasis when they are implemented in combination. The Pontryagin's maximum principle is adopted to find the necessary conditions for existence of the optimal controls. The Runge Kutta order four forward-backward sweep method is implemented in Matlab to solve the optimal control problem. The results indicate that a strategy which focuses on improving meat cooking and treatment of humans with taeniasis is the optimal strategy for diseases' control.
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Affiliation(s)
- Joshua A. Mwasunda
- Department of Applied Mathematics and Computational Science, The Nelson Mandela African Institution of Science and Technology, P.O.Box 447, Arusha, Tanzania
- Mathematics Department, Mkwawa University College of Education, P.O.Box 2513, Iringa, Tanzania
| | - Jacob I. Irunde
- Mathematics Department, Mkwawa University College of Education, P.O.Box 2513, Iringa, Tanzania
| | - Damian Kajunguri
- Mathematics Department, Kabale University, P.O. Box 317, Kabale, Uganda
| | - Dmitry Kuznetsov
- Department of Applied Mathematics and Computational Science, The Nelson Mandela African Institution of Science and Technology, P.O.Box 447, Arusha, Tanzania
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Pray IW, Pizzitutti F, Bonnet G, Gonzales-Gustavson E, Wakeland W, Pan WK, Lambert WE, Gonzalez AE, Garcia HH, O’Neal SE. Validation of a spatial agent-based model for Taenia solium transmission ("CystiAgent") against a large prospective trial of control strategies in northern Peru. PLoS Negl Trop Dis 2021; 15:e0009885. [PMID: 34705827 PMCID: PMC8575314 DOI: 10.1371/journal.pntd.0009885] [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: 01/12/2021] [Revised: 11/08/2021] [Accepted: 10/08/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The pork tapeworm (Taenia solium) is a parasitic helminth that imposes a major health and economic burden on poor rural populations around the world. As recognized by the World Health Organization, a key barrier for achieving control of T. solium is the lack of an accurate and validated simulation model with which to study transmission and evaluate available control and elimination strategies. CystiAgent is a spatially-explicit agent based model for T. solium that is unique among T. solium models in its ability to represent key spatial and environmental features of transmission and simulate spatially targeted interventions, such as ring strategy. METHODS/PRINCIPAL FINDINGS We validated CystiAgent against results from the Ring Strategy Trial (RST)-a large cluster-randomized trial conducted in northern Peru that evaluated six unique interventions for T. solium control in 23 villages. For the validation, each intervention strategy was replicated in CystiAgent, and the simulated prevalences of human taeniasis, porcine cysticercosis, and porcine seroincidence were compared against prevalence estimates from the trial. Results showed that CystiAgent produced declines in transmission in response to each of the six intervention strategies, but overestimated the effect of interventions in the majority of villages; simulated prevalences for human taenasis and porcine cysticercosis at the end of the trial were a median of 0.53 and 5.0 percentages points less than prevalence observed at the end of the trial, respectively. CONCLUSIONS/SIGNIFICANCE The validation of CystiAgent represented an important step towards developing an accurate and reliable T. solium transmission model that can be deployed to fill critical gaps in our understanding of T. solium transmission and control. To improve model accuracy, future versions would benefit from improved data on pig immunity and resistance, field effectiveness of anti-helminthic treatment, and factors driving spatial clustering of T. solium infections including dispersion and contact with T. solium eggs in the environment.
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Affiliation(s)
- Ian W. Pray
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Francesco Pizzitutti
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Gabrielle Bonnet
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Eloy Gonzales-Gustavson
- Tropical and Highlands Veterinary Research Institute, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, EL Mantaro, Peru
- School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Wayne Wakeland
- Systems Science Program, Portland State University, Portland, Oregon, United States of America
| | - William K. Pan
- Duke Global Health Institute & Nicholas School of Environment, Duke University, Durham, North Carolina, United States of America
| | - William E. Lambert
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
| | - Armando E. Gonzalez
- School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Hector H. Garcia
- School of Sciences, Department of Microbiology, Universidad Peruana Cayetano Heredia, Lima, Peru
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Tumbes, Peru
| | - Seth E. O’Neal
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America
- Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Tumbes, Peru
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Ngwili N, Johnson N, Wahome R, Githigia S, Roesel K, Thomas L. A qualitative assessment of the context and enabling environment for the control of Taenia solium infections in endemic settings. PLoS Negl Trop Dis 2021; 15:e0009470. [PMID: 34115758 PMCID: PMC8221787 DOI: 10.1371/journal.pntd.0009470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 06/23/2021] [Accepted: 05/12/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Taenia solium (T. solium), is a zoonotic helminth causing three diseases namely; taeniasis (in humans), neurocysticercosis (NCC, in humans) and porcine cysticercosis (PCC, in pigs) and is one of the major foodborne diseases by burden. The success or failure of control options against this parasite in terms of reduced prevalence or incidence of the diseases may be attributed to the contextual factors which underpin the design, implementation, and evaluation of control programmes. METHODOLOGY/PRINCIPAL FINDINGS The study used a mixed method approach combining systematic literature review (SLR) and key informant interviews (KII). The SLR focused on studies which implemented T. solium control programmes and was used to identify the contextual factors and enabling environment relevant to successful inception, planning and implementation of the interventions. The SLR used a protocol pre-registered at the International prospective register of systematic reviews (PROSPERO) number CRD42019138107 and followed PRISMA guidelines on reporting of SLR. To further highlight the importance and interlinkage of these contextual factors, KII were conducted with researchers/implementers of the studies included in the SLR. The SLR identified 41 publications that had considerations of the contextual factors. They were grouped into efficacy (10), effectiveness (28) and scale up or implementation (3) research studies. The identified contextual factors included epidemiological, socioeconomic, cultural, geographical and environmental, service and organizational, historical and financial factors. The enabling environment was mainly defined by policy and strategies supporting T. solium control. CONCLUSION/SIGNIFICANCE Failure to consider the contextual factors operating in target study sites was shown to later present challenges in project implementation and evaluation that negatively affected expected outcomes. This study highlights the importance of fully considering the various domains of the context and integrating these explicitly into the plan for implementation and evaluation of control programmes. Explicit reporting of these aspects in the resultant publication is also important to guide future work. The contextual factors highlighted in this study may be useful to guide future research and scale up of disease control programmes and demonstrates the importance of close multi-sectoral collaboration in a One Health approach.
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Affiliation(s)
- Nicholas Ngwili
- Animal and Human Health Program, International Livestock Research Institute, Nairobi, Kenya
- College of Agriculture and Veterinary Sciences, University of Nairobi, Nairobi, Kenya
| | - Nancy Johnson
- CGIAR Research program on Agriculture for Nutrition and Health, IFPRI, Washington, DC, United States of America
| | - Raphael Wahome
- College of Agriculture and Veterinary Sciences, University of Nairobi, Nairobi, Kenya
| | - Samuel Githigia
- College of Agriculture and Veterinary Sciences, University of Nairobi, Nairobi, Kenya
| | - Kristina Roesel
- Animal and Human Health Program, International Livestock Research Institute, Nairobi, Kenya
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Lian Thomas
- Animal and Human Health Program, International Livestock Research Institute, Nairobi, Kenya
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Lea Hurst Campus, Neston, United Kingdom
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Skrip LA, Dermauw V, Dorny P, Ganaba R, Millogo A, Tarnagda Z, Carabin H. Data-driven analyses of behavioral strategies to eliminate cysticercosis in sub-Saharan Africa. PLoS Negl Trop Dis 2021; 15:e0009234. [PMID: 33755677 PMCID: PMC8018642 DOI: 10.1371/journal.pntd.0009234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 04/02/2021] [Accepted: 02/10/2021] [Indexed: 01/25/2023] Open
Abstract
Background The multi-host taeniosis/cysticercosis disease system is associated with significant neurological morbidity, as well as economic burden, globally. We investigated whether lower cost behavioral interventions are sufficient for local elimination of human cysticercosis in Boulkiemdé, Sanguié, and Nayala provinces of Burkina Faso. Methodology/Principal findings Province-specific data on human behaviors (i.e., latrine use and pork consumption) and serological prevalence of human and pig disease were used to inform a deterministic, compartmental model of the taeniosis/cysticercosis disease system. Parameters estimated via Bayesian melding provided posterior distributions for comparing transmission rates associated with human ingestion of Taenia solium cysticerci due to undercooking and human exposure to T. solium eggs in the environment. Reductions in transmission via these pathways were modeled to determine required effectiveness of a market-focused cooking behavior intervention and a community-led sanitation and hygiene program, independently and in combination, for eliminating human cysticercosis as a public health problem (<1 case per 1000 population). Transmission of cysticerci due to consumption of undercooked pork was found to vary significantly across transmission settings. In Sanguié, the rate of transmission due to undercooking was 6% higher than that in Boulkiemdé (95% CI: 1.03, 1.09; p-value < 0.001) and 35% lower than that in Nayala (95% CI: 0.64, 0.66; p-value < 0.001). We found that 67% and 62% reductions in undercooking of pork consumed in markets were associated with elimination of cysticercosis in Nayala and Sanguié, respectively. Elimination of active cysticercosis in Boulkiemdé required a 73% reduction. Less aggressive reductions of 25% to 30% in human exposure to Taenia solium eggs through sanitation and hygiene programs were associated with elimination in the provinces. Conclusions/Significance Despite heterogeneity in effectiveness due to local transmission dynamics and behaviors, education on the importance of proper cooking, in combination with community-led sanitation and hygiene efforts, has implications for reducing morbidity due to cysticercosis and neurocysticercosis. It is important to consider context-specific behaviors and transmission pathways when designing scalable and sustainable intervention strategies for neglected tropical diseases (NTDs). To reduce the morbidity and mortality associated with cysticercosis, suites of interventions have been recommended but are inconsistently implemented due to cost and feasibility-related constraints. This study investigated the potential of a cooking intervention to interrupt transmission via undercooked pork in marketplaces of Burkina Faso. The sensitivity of Taenia solium parasite to temperatures attainable via improved cooking strategies provides a low-cost, human-centered approach to prevent consumption of infected pork meals. By accounting for differential behavior and the relative role of this transmission route across three provinces, we show how the potential of cysticercosis elimination (as a public health problem) varies across behavior-focused interventions. Further investigation into intervention strategies against human and pig cysticercosis warrants data-driven analyses that account for local variation in transmission behaviors.
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Affiliation(s)
| | - Veronique Dermauw
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Pierre Dorny
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | | | - Athanase Millogo
- Department of Medicine, CHU Sourô Sanou, Bobo Dioulasso, Burkina Faso
| | - Zékiba Tarnagda
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo Dioulasso, Burkina Faso
| | - Hélène Carabin
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada
- Département de médecine sociale et préventive, École de Santé Publique, Université de Montréal, Montréal, Québec, Canada
- Centre de recherche en Santé Publique (CReSP), Montréal, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, St-Hyacinthe, Québec, Canada
- * E-mail:
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Pray IW, Wakeland W, Pan W, Lambert WE, Garcia HH, Gonzalez AE, O'Neal SE. Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model. Parasit Vectors 2020; 13:372. [PMID: 32709250 PMCID: PMC7379812 DOI: 10.1186/s13071-020-04226-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 07/14/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The pork tapeworm, Taenia solium, is a serious public health problem in rural low-resource areas of Latin America, Africa and Asia, where the associated conditions of nuerocysticercosis (NCC) and porcine cysticercosis cause substantial health and economic harms. An accurate and validated transmission model for T. solium would serve as an important new tool for control and elimination, as it would allow for comparison of available intervention strategies, and prioritization of the most effective strategies for control and elimination efforts. METHODS We developed a spatially-explicit agent-based model (ABM) for T. solium ("CystiAgent") that differs from prior T. solium models by including a spatial framework and behavioral parameters such as pig roaming, open human defecation, and human travel. In this article, we introduce the structure and function of the model, describe the data sources used to parameterize the model, and apply sensitivity analyses (Latin hypercube sampling-partial rank correlation coefficient (LHS-PRCC)) to evaluate model parameters. RESULTS LHS-PRCC analysis of CystiAgent found that the parameters with the greatest impact on model uncertainty were the roaming range of pigs, the infectious duration of human taeniasis, use of latrines, and the set of "tuning" parameters defining the probabilities of infection in humans and pigs given exposure to T. solium. CONCLUSIONS CystiAgent is a novel ABM that has the ability to model spatial and behavioral features of T. solium transmission not available in other models. There is a small set of impactful model parameters that contribute uncertainty to the model and may impact the accuracy of model projections. Field and laboratory studies to better understand these key components of transmission may help reduce uncertainty, while current applications of CystiAgent may consider calibration of these parameters to improve model performance. These results will ultimately allow for improved interpretation of model validation results, and usage of the model to compare available control and elimination strategies for T. solium.
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Affiliation(s)
- Ian W Pray
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, OR, USA.
| | - Wayne Wakeland
- Systems Science Program, Portland State University, Portland, OR, USA
| | - William Pan
- Global Health Institute, Duke University, Durham, NC, USA
| | - William E Lambert
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, OR, USA
| | - Hector H Garcia
- School of Sciences, Department of Microbiology, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Armando E Gonzalez
- School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Seth E O'Neal
- School of Public Health, Oregon Health & Science University and Portland State University, Portland, OR, USA
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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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The World Health Organization 2030 goals for Taenia solium: Insights and perspectives from transmission dynamics modelling: CystiTeam Group for Epidemiology and Modelling of Taenia solium Taeniasis/Cysticercosis. Gates Open Res 2019; 3:1546. [PMID: 31701092 PMCID: PMC6820453 DOI: 10.12688/gatesopenres.13068.2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2019] [Indexed: 12/14/2022] Open
Abstract
Taenia solium (TS), responsible for porcine cysticercosis, human taeniasis and (neuro)cysticercosis, was included in the World Health Organization neglected tropical disease (NTD) roadmap published in 2012. Targets set in this roadmap have not been met, but T. solium has been included in the consultation process for the new 2030 goals proposed for priority NTDs. Taenia solium transmission dynamics models can contribute to this process. A recent review has compared existing T. solium transmission models, identifying their similarities and differences in structure, parameterization and modelled intervention approaches. While a formal model comparison to investigate the impact of interventions is yet to be conducted, the models agree on the importance of coverage for intervention effectiveness and on the fact that human- and pig-focused interventions can be optimally combined. One of these models, cystiSim, an individual-based, stochastic model has been used to assess field-applicable interventions, some currently under evaluation in on-going trials in Zambia. The EPICYST, population-based, deterministic model has highlighted, based on simulating a generic sub-Saharan Africa setting, the higher efficacy (measured as the percentage of human cysticercosis cases prevented) of biomedical interventions (human and pig treatment and pig vaccination) compared to improved husbandry, sanitation, and meat inspection. Important questions remain regarding which strategies and combinations thereof provide sustainable solutions for severely resource-constrained endemic settings. Defining realistic timeframes to achieve feasible targets, and establishing suitable measures of effectiveness for these targets that can be quantified with current monitoring and evaluation tools, are current major barriers to identifying validated strategies. Taenia solium transmission models can support setting achievable 2030 goals; however, the refinement of these models is first required. Incorporating socio-economic elements, improved understanding of underlying biological processes, and consideration of spatial dynamics are key knowledge gaps that need addressing to support model development.
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The World Health Organization 2030 goals for Taenia solium: Insights and perspectives from transmission dynamics modelling: CystiTeam Group for Epidemiology and Modelling of Taenia solium Taeniasis/Cysticercosis. Gates Open Res 2019. [PMID: 31701092 DOI: 10.12688/gatesopenres.13068.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Taenia solium (TS), responsible for porcine cysticercosis, human taeniasis and (neuro)cysticercosis, was included in the World Health Organization neglected tropical disease (NTD) roadmap published in 2012. Targets set in this roadmap have not been met, but T. solium has been included in the consultation process for the new 2030 goals proposed for priority NTDs. Taenia solium transmission dynamics models can contribute to this process. A recent review has compared existing T. solium transmission models, identifying their similarities and differences in structure, parameterization and modelled intervention approaches. While a formal model comparison to investigate the impact of interventions is yet to be conducted, the models agree on the importance of coverage for intervention effectiveness and on the fact that human- and pig-focused interventions can be optimally combined. One of these models, cystiSim, an individual-based, stochastic model has been used to assess field-applicable interventions, some currently under evaluation in on-going trials in Zambia. The EPICYST, population-based, deterministic model has highlighted, based on simulating a generic sub-Saharan Africa setting, the higher efficacy (measured as the percentage of human cysticercosis cases prevented) of biomedical interventions (human and pig treatment and pig vaccination) compared to improved husbandry, sanitation, and meat inspection. Important questions remain regarding which strategies and combinations thereof provide sustainable solutions for severely resource-constrained endemic settings. Defining realistic timeframes to achieve feasible targets, and establishing suitable measures of effectiveness for these targets that can be quantified with current monitoring and evaluation tools, are current major barriers to identifying validated strategies. Taenia solium transmission models can support setting achievable 2030 goals; however, the refinement of these models is first required. Incorporating socio-economic elements, improved understanding of underlying biological processes, and consideration of spatial dynamics are key knowledge gaps that need addressing to support model development.
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Ngowi HA, Winkler AS, Braae UC, Mdegela RH, Mkupasi EM, Kabululu ML, Lekule FP, Johansen MV. Taenia solium taeniosis and cysticercosis literature in Tanzania provides research evidence justification for control: A systematic scoping review. PLoS One 2019; 14:e0217420. [PMID: 31166983 PMCID: PMC6550401 DOI: 10.1371/journal.pone.0217420] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 05/11/2019] [Indexed: 11/19/2022] Open
Abstract
Background Despite Taenia solium taeniosis/cysticercosis (TSTC) having been put high on the global agenda of neglected tropical diseases (NTDs), which over the last years has received a lot of attention, there has been no control programmes in place in sub-Saharan Africa, a highly endemic region. This could be attributed to lack of awareness of many stakeholders on the burden and impact of T. solium. This information is essential in guiding TSTC policies, practices and research agendas as well as encouraging cross-sectoral collaboration in the control of this important zoonotic parasite using a One Health approach. National elimination of the parasite is the foundation for global eradication. This will require that substantial country-level information is provided to all key stakeholders. We have mapped out TSTC research evidence in Tanzania to inform on disease burden and potential for integrated control measures. Methodology/Principal findings A scoping review of all TSTC studies undertaken in Tanzania and published up to December 2018 was conducted. The articles were searched from PUBMED, AJOL, Google Scholar and Google in general. Fifty-one (51) articles met the inclusion criteria and were reviewed. Prevalence of taeniosis of 2.3% - 5.2% was estimated based on copro-antigen ELISA while human cysticercosis of >16% was estimated based on serum antigen ELISA (Ag-ELISA) or IgG Western Blot. Neurocysticercosis (NCC) contributed significantly to epilepsy in adults. Farm prevalence of porcine cysticercosis were 6.0% - 17.4% (lingual examination) and 1.5% - 33.3% (Ag-ELISA). Slaughter-slab prevalence were 0% - 18.2% (routine meat inspection). Lacking latrines, watering pigs with river or pond water, and feeding pigs with potato peels were associated with porcine cysticercosis prevalence. Washing hands by dipping method increased the risk of human cysticercosis. In 2012, the number of DALYs/1000 person-years for NCC-associated epilepsy was 0.7 (95% UI, 0.2–1.6), around 5 million USD (95% UI, 797,535–16,933,477) were spent due to NCC-associated epilepsy and nearly 3 million USD (95% UI, 1,095,960–5,366,038) were potentially lost due to porcine cysticercosis. Three rounds of annual treatment of school-age children with praziquantel significantly reduced prevalence of taeniosis and porcine cysticercosis. Health education was efficacious in improving knowledge and attitudes favourable for control of TSTC while a single dose of oxfendazole 30 mg/kg body weight was efficacious in eliminating T. solium cysticerci from pig musculature. Conclusions/Significance The observed high burden of TSTC and the significant contribution of NCC to epilepsy in Tanzania warrant urgent interventions. Evaluation of best control options should make use of disease transmission dynamics models such as cystiSim, taking into account findings from the field based intervention studies. In addition, locally adapted management guidelines for people suffering from NCC are urgently needed.
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Affiliation(s)
- Helena Aminiel Ngowi
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
- * E-mail:
| | - Andrea Sylvia Winkler
- Center for Global Health, Department of Neurology, Technical University of Munich, Munich, Germany
- Centre for Global Health, Department of Community Medicine and Global Health, Institute of Health and Society, University of Oslo, Oslo, Norway
| | - Uffe Christian Braae
- One Health Center for Zoonoses and Tropical Veterinary Medicine, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis
- Department of Infectious Disease Epidemiology and Prevention, Statens Serum Institut, Copenhagen, Denmark
| | | | - Ernatus Martin Mkupasi
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
| | | | - Faustin Peter Lekule
- Department of Animal Science and Production, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Maria Vang Johansen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Braae UC, Lightowlers MW, Donadeu M. Can We Recommend Practical Interventions to Prevent Neurocysticercosis? Trends Parasitol 2019; 35:592-595. [PMID: 31151880 DOI: 10.1016/j.pt.2019.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 10/26/2022]
Abstract
The cystiSim model was used to compare strategies for the control of Taenia solium. A three-monthly intervention in pigs for 3 years was substantially more effective than biannual treatment for taeniasis in the human population for 5 years. The intervention period could be shortened further by combining pig and human interventions.
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Affiliation(s)
- Uffe Christian Braae
- Department of Infectious Disease Epidemiology and Prevention, Statens Serum Institut, DK-2300, Copenhagen, Denmark; One Health Center for Zoonoses and Tropical Veterinary Medicine, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis
| | - Marshall W Lightowlers
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
| | - Meritxell Donadeu
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia; Initiative for Neglected Animal Diseases (INAND), Whitby Manor Office Estate, 14th Road, Midrand, South Africa
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Strategies for tackling Taenia solium taeniosis/cysticercosis: A systematic review and comparison of transmission models, including an assessment of the wider Taeniidae family transmission models. PLoS Negl Trop Dis 2019; 13:e0007301. [PMID: 30969966 PMCID: PMC6476523 DOI: 10.1371/journal.pntd.0007301] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 04/22/2019] [Accepted: 03/13/2019] [Indexed: 01/03/2023] Open
Abstract
Background The cestode Taenia solium causes the neglected (zoonotic) tropical disease cysticercosis, a leading cause of preventable epilepsy in endemic low and middle-income countries. Transmission models can inform current scaling-up of control efforts by helping to identify, validate and optimise control and elimination strategies as proposed by the World Health Organization (WHO). Methodology/Principal findings A systematic literature search was conducted using the PRISMA approach to identify and compare existing T. solium transmission models, and related Taeniidae infection transmission models. In total, 28 modelling papers were identified, of which four modelled T. solium exclusively. Different modelling approaches for T. solium included deterministic, Reed-Frost, individual-based, decision-tree, and conceptual frameworks. Simulated interventions across models agreed on the importance of coverage for impactful effectiveness to be achieved. Other Taeniidae infection transmission models comprised force-of-infection (FoI), population-based (mainly Echinococcus granulosus) and individual-based (mainly E. multilocularis) modelling approaches. Spatial structure has also been incorporated (E. multilocularis and Taenia ovis) in recognition of spatial aggregation of parasite eggs in the environment and movement of wild animal host populations. Conclusions/Significance Gaps identified from examining the wider Taeniidae family models highlighted the potential role of FoI modelling to inform model parameterisation, as well as the need for spatial modelling and suitable structuring of interventions as key areas for future T. solium model development. We conclude that working with field partners to address data gaps and conducting cross-model validation with baseline and longitudinal data will be critical to building consensus-led and epidemiological setting-appropriate intervention strategies to help fulfil the WHO targets. Taenia solium infection in humans (taeniosis and neurocysticercosis) and pigs (cysticercosis) presents a significant global public health and economic challenge. The World Health Organization has called for validated strategies and wider consensus on which strategies are suitable for different epidemiological settings to support successful T. solium control and elimination efforts. Transmission models can be used to inform these strategies. Therefore, a modelling review was undertaken to assess the current state and gaps relating to T. solium epidemiological modelling. The literature surrounding models for other Taeniidae family infections was also considered, identifying approaches to aid further development of existing T. solium models. A variety of different modelling approaches have been used for T. solium including differences in structural and parametric assumptions associated with T. solium transmission biology. Despite these differences, all models agreed on the importance of coverage on intervention effectiveness. Other Taeniidae family models highlighted the need for incorporating spatial structure when necessary to capture aggregation of transmission stages in the environment and movement of animal hosts.
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How to eliminate taeniasis/cysticercosis: porcine vaccination and human chemotherapy (Part 2). Theor Biol Med Model 2019; 16:4. [PMID: 30803437 PMCID: PMC6390339 DOI: 10.1186/s12976-019-0100-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 01/29/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The application of effective vaccines against pig cysticercosis and mass chemotherapy against pig cysticercosis and human taeniasis have shown the feasibility of interrupting the parasite's life cycle in endemic areas. METHODS A mathematical model that divides the population into susceptible, infected, and vaccinated individuals is formulated. The model is based upon the life cycle of the parasite. Computer numerical simulation experiments to evaluate the impact of pig vaccination under different vaccination schedules, and combined intervention strategies including pig vaccination and anthelmintic treatment against human taeniasis are carried out. RESULTS Vaccination against either pig cysticercosis or against human taeniasis will influence the transmission dynamics not only among vaccinees but also the dynamics of the other hosts as well. When the protective efficacy and/or the coverage rate is less than 100%, different mass interventions like vaccinating the pig population twice in combination with chemotherapeutic treatment against human taeniasis, the elimination of the infection in both pigs and humans can also be achieved. CONCLUSIONS Our mathematical model has the potential for planning, and designing effective intervention strategies including both mass vaccination and/or chemotherapeutic treatment to eliminate pig cysticercosis, human taeniasis and human neurocysticercosis. The model can be adapted to any given community with mild, moderate endemicity, or even in hyperendemic regions.
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José MV, Bobadilla JR, Sánchez-Torres NY, Laclette JP. Mathematical model of the life cycle of taenia-cysticercosis: transmission dynamics and chemotherapy (Part 1). Theor Biol Med Model 2018; 15:18. [PMID: 30449280 PMCID: PMC6241031 DOI: 10.1186/s12976-018-0090-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Taenia solium is the aetiological agent of human taeniasis, pig cysticercosis and human neurocysticercosis, which are serious public health problems, especially in developing countries. METHODS A mathematical model of the transmission dynamics of taeniasis-cysticercosis is formulated. The model consists of a coupled system of differential equations, which are density-dependent equations for describing the flow of the parasite through the life cycle. The model is hybrid since it comprises deterministic equations with stochastic elements which describe changes in the mean parasite burden and incorporates the overall pattern of the parasites' distribution. RESULTS Sensitivity and bifurcation analyses were carried out to determine the range of values of the model. The model can reproduce the observed epidemiological patterns of human taeniasis, pig and human cysticercosis. For example, for a wide range of parameter values, the mean intensity of adult worms tends to rapidly stabilize in one parasite per individual host. From this model, we also derived a Susceptible-Infected model to describe the prevalence of infection in humans and pigs. Chemotherapeutic interventions against pig cysticercosis or human taeniasis may reduce rapidly and effectively the mean intensity of human taeniasis, pig cysticercosis and human cysticercosis. This effect can be achieved even if the protective efficacy of the drug is of the order of 90% and the coverage rate is 90%. This means that health in humans infected either with adult worms or cysticerci may be achieved by the application of anthelmintic drugs against pig cysticercosis. However, treatment against human cysticercosis alone, does not influence neither human teniasis nor pig cysticercosis. This is because human cysticercosis infection does not influence the value of the basic reproductive number (Ro). CONCLUSIONS Even coverage of 100% in the administration of anthelmintics did not eliminate the infection. Then elimination of the infection in all hosts does not seem a feasible goal to achieve by administering only chemotherapeutic interventions. Throughout the manuscript a discussion of our model in the context of other models of taeniasis-cysticercosis is presented.
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Affiliation(s)
- Marco V. José
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 CDMX, Mexico
| | - Juan R. Bobadilla
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 CDMX, Mexico
| | - Norma Y. Sánchez-Torres
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 CDMX, Mexico
| | - Juan Pedro Laclette
- Department of Immunology, Biomedical Research Institute, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 CDMX, Mexico
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de Coster T, Van Damme I, Baauw J, Gabriël S. Recent advancements in the control of Taenia solium: A systematic review. Food Waterborne Parasitol 2018; 13:e00030. [PMID: 32095601 PMCID: PMC7034013 DOI: 10.1016/j.fawpar.2018.e00030] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 01/07/2023] Open
Abstract
The combined health and economic impact of Taenia solium urges for control and, if possible, elimination of this neglected parasitic zoonosis. Up till now there is still no consensus about the most cost-effective and feasible approaches for control. The objective of this systematic review is to identify and summarize the evidence in English scientific literature on the control and elimination of T. solium since 2014, based on the rapidly evolving field of evidence on control and elimination of T. solium. The search resulted in the identification of 458 records of which 31 were included, covering 13 field trials and 18 articles containing experimental data, mathematical models, and other information directly relevant the control of T. solium. Recent field studies confirm that combinations of interventions or multiple rounds are more successful in obtaining rapid reductions in transmission and parasite occurrence, with the quick impact of the combination of human and pig treatment confirmed in a South Asian and Peruvian context. Moreover, elimination of transmission through a one-year intensive program, combining human and pig treatment/vaccination was described in a Peruvian study. Recent studies also provide more data on the positive impact of specific health education, as well as newly developed electronic educational tools, providing opportunities for area specific community-engaged participatory interventions. Once control has been achieved, monitoring of migration of both potentially infected people and pigs from outside the control area is important for sustained disease control. Combined intervention field studies demonstrate sharp decreases in disease occurrence. New, specific, efficient, electronic educational tools are available. Elimination of Taenia solium in a Peruvian endemic area has been described. Integration of Taenia solium control in other NTD control programs can be effective.
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Affiliation(s)
- T de Coster
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - I Van Damme
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - J Baauw
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - S Gabriël
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
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Okello WO, Okello AL, Inthavong P, Tiemann T, Phengsivalouk A, Devleesschauwer B, Shaw A, Allen J. Improved methods to capture the total societal benefits of zoonotic disease control: Demonstrating the cost-effectiveness of an integrated control programme for Taenia solium, soil transmitted helminths and classical swine fever in northern Lao PDR. PLoS Negl Trop Dis 2018; 12:e0006782. [PMID: 30231029 PMCID: PMC6185856 DOI: 10.1371/journal.pntd.0006782] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/12/2018] [Accepted: 08/23/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Control and elimination of zoonotic diseases requires robust information about their effect on both human and livestock health in order to enable policy formulation and the allocation of resources. This study aimed to evaluate the cost-effectiveness of controlling Taenia solium taeniasis/cysticercosis in both humans and pigs, and soil-transmitted helminths (STH) in humans by integrating their control to on-going human and animal health control programmes in northern Lao People's Democratic Republic. METHOD A cross-sectional study was carried out in 49 households, focusing on the prevalence of T. solium taenias/cysticercosis and soil transmitted helminths before and after a twelve month intervention. The village data was collected using a semi-structured questionnaire through a door-to-door survey. The village data was then projected to the wider northern Lao PDR population using stochastic modelling and cost-effectiveness ratio (after aggregating the net cost to capture both human and animal health parameters) and GDP per capita as a threshold, to determine the cost-effectiveness of the integrated control of T. solium taeniasis/ cysticercosis and STH, assuming linear scaling out of the intervention. The zoonotic DALY (zDALY) approach was also used as an alternative method of estimating the cost-effectiveness ratio of controlling T. solium taeniasis/cysticercosis in humans and pigs. FINDINGS Using cost-effectiveness analysis after aggregating the net cost and control of T. solium taeniasis/cysticercosis alone as the base case, the study found that simultaneous control of T. solium taeniasis/cysticercosis in humans and pigs, STH in humans and Classical Swine Fever (CSF) in pigs was USD 14 per DALY averted and USD 234 per zDALY averted using zDALY method hence considered highly cost-effective whereas controlling T. solium taeniasis/cysticercosis without incorporating STH and CSF was the least cost-effective (USD 3,672 per DALY averted). Additionally, the cost-effectiveness of controlling T. solium taeniasis/cysticercosis in people and pigs using zDALY as an alternative method was USD 3,662 per zDALY averted which was quite close to our findings using the aggregate net cost method. CONCLUSION The study showed that control of T. solium taeniasis/cysticercosis alone in humans and pigs is not cost-effective in northern Lao PDR whereas control of STH is. Consequently, integrating T. solium taeniasis/cysticercosis control with other cost-effective programmes such as STH and CSF markedly improved the cost-effectiveness of the intervention. This is especially important in low resource countries where control of zoonotic neglected tropical diseases could be integrated with the human and animal health sectors to optimize use of the limited resources. TRIAL REGISTRATION Australia New Zealand Clinical Trials Registry (ANZCTR) ACTRN12614001067662.
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Affiliation(s)
- Walter O. Okello
- Division of Infection and Pathway Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Anna L. Okello
- Australian Animal Health Laboratory (AAHL) Regional Program, CSIRO, Geelong, VIC, Australia
| | - Phouth Inthavong
- Department of Livestock and Fisheries, National Animal Health Laboratory (NAHL), Vientiane, Lao PDR
| | - Tassilo Tiemann
- Tropical Forages Program, Centro Internacional de Agricultura Tropical (CIAT in Asia), Vientiane, Lao PDR
| | - Ammaly Phengsivalouk
- Department of Livestock and Fisheries, National Animal Health Laboratory (NAHL), Vientiane, Lao PDR
| | - Brecht Devleesschauwer
- Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Alexandra Shaw
- Division of Infection and Pathway Medicine, University of Edinburgh, Edinburgh, United Kingdom
- A P Consultants, Andover, United Kingdom
| | - John Allen
- Australian Animal Health Laboratory (AAHL) Regional Program, CSIRO, Geelong, VIC, Australia
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Effectiveness of a community-based educational programme in reducing the cumulative incidence and prevalence of human Taenia solium cysticercosis in Burkina Faso in 2011-14 (EFECAB): a cluster-randomised controlled trial. LANCET GLOBAL HEALTH 2018. [PMID: 29530423 PMCID: PMC5873982 DOI: 10.1016/s2214-109x(18)30027-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background The effectiveness of drug-free interventions in controlling human cysticercosis is not well known. We aimed to estimate the effectiveness of a community-based educational intervention in reducing the frequency of human cysticercosis in Burkina Faso. Methods We did a cluster-randomised controlled trial between 2011 and 2014. 60 eligible villages from three provinces (Boulkiemdé, Sanguié, and Nayala) were randomly allocated to the intervention or control group. Villages raising pigs, that were not a regional capital or located on a main road, that were more than 20 km from Ouagadougou or 5 km from one another, were eligible. In each village, 60 participants were asked for blood samples at baseline, 18 months later (before randomisation), and 18 months after randomisation. Villages were block randomised (1:1) by pig-raising department immediately after the pre-randomisation visit. The intervention aimed to improve knowledge of Taenia solium transmission and control through screening and structured discussion of a 52-min movie, and to increase community self-efficacy through a Self-esteem, Associative strengths, Resourcefulness, Action planning, Responsibility (SARAR) approach via the Participatory Hygiene and Sanitation Transformation (PHAST) model. The primary outcome was active cysticercosis, defined as the presence of circulating antigens detected by use of B158/B60 ELISA. Effectiveness measured at the village level was estimated by use of three Bayesian hierarchical models. This study is registered with ClinicalTrials.gov, number NCT0309339. Findings Two villages in the same randomisation block were excluded, resulting in a final sample size of 58 villages. Overall, the intervention tended towards a decrease in the cumulative incidence of active cysticercosis from baseline to after randomisation (adjusted cumulative incidence ratio 0·65, 95% Bayesian credible interval [95% CrI] 0·39–1·05) and a decrease in active cysticercosis prevalence from baseline to after randomisation (adjusted prevalence proportion ratio 0·84; 95% CrI 0·59–1·18). The intervention was shown to be effective in Nayala and Sanguié but not in Boulkiemdé. Interpretation Community-engaged participatory interventions can be effective at reducing the incidence and prevalence of cysticercosis in some low-resource settings. Funding US National Institutes of Health (National Institute of Neurological Disorders and Stroke, Fogarty International Center, and National Institute of General Medical Sciences).
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Identification and control of sources of Taenia solium infection – the attempts to eradicate the parasite. J Vet Res 2018. [DOI: 10.2478/jvetres-2018-0004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Taenia solium is a parasite causing porcine cysticercosis and human taeniosis and cysticercosis, parasitic zoonoses with a serious public health and economic influence. It has been globally ranked as the top foodborne parasite by the Food and Agriculture Organisation of the United Nations (FAO) and the World Health Organisation (WHO). This parasite is transmitted mainly in countryside regions where animals are free roaming, having access to human faeces, and infected pork is widely available. More developed countries eliminated cysticercosis; nonetheless, there are insufficient data about the current endemicity status of T. solium, due to increased human migration from endemic areas. Formally submitted statistics on cysticercosis in pigs are extremely inadequate. This is the result of not reporting all cases of the disease by some countries and lack of molecular verification during identification of the parasite. There is a need to develop diagnostic tests with increased sensitivity and specificity. The purpose of the present review is to summarise current knowledge about diagnostic and control methods concerning T. solium infection. The article does not address the diagnostics of human cysticercosis, since there is a distinct medical field which should be discussed separately. The paper focuses mainly on identifying the sources of T. solium infection, presenting the methods to detect and control porcine cysticercosis and taeniosis in humans.
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Samorek-Pieróg M, Karamon J, Cencek T. Identification and Control of Sources of Taenia Solium Infection - the Attempts To Eradicate the Parasite. J Vet Res 2018; 62:27-34. [PMID: 29978124 PMCID: PMC5957458 DOI: 10.1515/jvetres-2018-0004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/15/2018] [Indexed: 11/15/2022] Open
Abstract
Taenia solium is a parasite causing porcine cysticercosis and human taeniosis and cysticercosis, parasitic zoonoses with a serious public health and economic influence. It has been globally ranked as the top foodborne parasite by the Food and Agriculture Organisation of the United Nations (FAO) and the World Health Organisation (WHO). This parasite is transmitted mainly in countryside regions where animals are free roaming, having access to human faeces, and infected pork is widely available. More developed countries eliminated cysticercosis; nonetheless, there are insufficient data about the current endemicity status of T. solium, due to increased human migration from endemic areas. Formally submitted statistics on cysticercosis in pigs are extremely inadequate. This is the result of not reporting all cases of the disease by some countries and lack of molecular verification during identification of the parasite. There is a need to develop diagnostic tests with increased sensitivity and specificity. The purpose of the present review is to summarise current knowledge about diagnostic and control methods concerning T. solium infection. The article does not address the diagnostics of human cysticercosis, since there is a distinct medical field which should be discussed separately. The paper focuses mainly on identifying the sources of T. solium infection, presenting the methods to detect and control porcine cysticercosis and taeniosis in humans.
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Affiliation(s)
- Małgorzata Samorek-Pieróg
- Department of Parasitology and Invasive Diseases, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Jacek Karamon
- Department of Parasitology and Invasive Diseases, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Tomasz Cencek
- Department of Parasitology and Invasive Diseases, National Veterinary Research Institute, 24-100 Pulawy, Poland
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White LA, Forester JD, Craft ME. Covariation between the physiological and behavioral components of pathogen transmission: host heterogeneity determines epidemic outcomes. OIKOS 2017. [DOI: 10.1111/oik.04527] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Lauren A. White
- Dept of Ecology, Evolution and Behavior; Univ. of Minnesota, 140 Gortner Laboratory; 1479 Gortner Avenue St. Paul MN 55108 USA
| | - James D. Forester
- Dept of Fisheries, Wildlife and Conservation Biology; Univ. of Minnesota; St. Paul MN USA
| | - Meggan E. Craft
- Veterinary Population Medicine, Univ. of Minnesota; St. Paul MN USA
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Okello AL, Thomas LF. Human taeniasis: current insights into prevention and management strategies in endemic countries. Risk Manag Healthc Policy 2017; 10:107-116. [PMID: 28615981 PMCID: PMC5461055 DOI: 10.2147/rmhp.s116545] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Human taeniasis is a zoonotic condition resulting from infection with the adult stages of Taenia saginata ("beef tapeworm"), Taenia solium ("pork tapeworm") or Taenia asiatica ("Asian tapeworm"). Although these parasites have a worldwide distribution, the overwhelming burden is felt by communities in low- and middle-income countries. This is particularly true for T. solium, whereby infection of the central nervous system with the larval stage of the parasite (neurocysticercosis) is a major cause of acquired epilepsy in low-resource settings. With a focus on endemic countries, this review provides an insight into the prevention and management of human taeniasis, concluding with some recent case studies describing their implementation. Discussion of the opportunities and challenges regarding current fecal and serological diagnostic assays for detecting Taenia spp. highlights the importance of accurate and accessible diagnostic options for the field situation. The lack of long-term impact on the parasites' lifecycle from human anthelmintic treatment, coupled with the propensity for adverse reactions, highlights the importance of a "two-pronged" approach that considers the relevant animal hosts, particularly in the case of T. solium. Aside from the therapeutic options, this review reiterates the importance of adequate assessment and consideration of the associated behavioral and policy aspects around sanitation, hygiene and meat inspection that have been shown to support parasite control, and potential elimination, in endemic regions.
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Affiliation(s)
- Anna L Okello
- Division of Infection and Pathway Medicine, Edinburgh Medical School, Biomedical Sciences College of Medicine and Veterinary Medicine, University of Edinburgh, Scotland
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Designing a Minimal Intervention Strategy to Control Taenia solium. Trends Parasitol 2017; 33:426-434. [DOI: 10.1016/j.pt.2017.01.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/13/2017] [Accepted: 01/23/2017] [Indexed: 11/21/2022]
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Winskill P, Harrison WE, French MD, Dixon MA, Abela-Ridder B, Basáñez MG. Assessing the impact of intervention strategies against Taenia solium cysticercosis using the EPICYST transmission model. Parasit Vectors 2017; 10:73. [PMID: 28183336 PMCID: PMC5301381 DOI: 10.1186/s13071-017-1988-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 01/14/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The pork tapeworm, Taenia solium, and associated human infections, taeniasis, cysticercosis and neurocysticercosis, are serious public health problems, especially in developing countries. The World Health Organization (WHO) has set goals for having a validated strategy for control and elimination of T. solium taeniasis/cysticercosis by 2015 and interventions scaled-up in selected countries by 2020. Timely achievement of these internationally-endorsed targets requires that the relative benefits and effectiveness of potential interventions be explored rigorously within a quantitative framework. METHODS A deterministic, compartmental transmission model (EPICYST) was developed to capture the dynamics of the taeniasis/cysticercosis disease system in the human and pig hosts. Cysticercosis prevalence in humans, an outcome of high epidemiological and clinical importance, was explicitly modelled. A next generation matrix approach was used to derive an expression for the basic reproduction number, R 0. A full sensitivity analysis was performed using a methodology based on Latin-hypercube sampling partial rank correlation coefficient index. RESULTS EPICYST outputs indicate that chemotherapeutic intervention targeted at humans or pigs would be highly effective at reducing taeniasis and cysticercosis prevalence when applied singly, with annual chemotherapy of humans and pigs resulting, respectively, in 94 and 74% of human cysticercosis cases averted. Improved sanitation, meat inspection and animal husbandry are less effective but are still able to reduce prevalence singly or in combination. The value of R 0 for taeniasis was estimated at 1.4 (95% Credible Interval: 0.5-3.6). CONCLUSIONS Human- and pig-targeted drug-focussed interventions appear to be the most efficacious approach from the options currently available. The model presented is a forward step towards developing an informed control and elimination strategy for cysticercosis. Together with its validation against field data, EPICYST will be a valuable tool to help reach the WHO goals and to conduct economic evaluations of interventions in varying epidemiological settings.
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Affiliation(s)
- Peter Winskill
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
| | - Wendy E. Harrison
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St. Mary’s Campus, London, W2 1PG UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
| | - Michael D. French
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St. Mary’s Campus, London, W2 1PG UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
- Current address: Research Triangle Institute, 701 13st Street NW, Washington D.C., 20005 USA
| | - Matthew A. Dixon
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
| | - Bernadette Abela-Ridder
- Neglected Zoonotic Diseases Team, Department of Neglected Tropical Diseases (NTD), World Health Organization (WHO), 20 Avenue Appia, 1211, Geneva 27, Switzerland
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary’s Campus, London, W2 1PG UK
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Braae UC, Magnussen P, Ndawi B, Harrison W, Lekule F, Johansen MV. Effect of repeated mass drug administration with praziquantel and track and treat of taeniosis cases on the prevalence of taeniosis in Taenia solium endemic rural communities of Tanzania. Acta Trop 2017; 165:246-251. [PMID: 26597324 DOI: 10.1016/j.actatropica.2015.10.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 10/09/2015] [Accepted: 10/16/2015] [Indexed: 10/22/2022]
Abstract
This study evaluated the effect of mass drug administration (MDA) with praziquantel administered to school-aged children (SAC) combined with 'track and treat' of taeniosis cases in the general population on the copro-antigen (Ag) prevalence of taeniosis. The study was conducted in 14 villages in Mbozi and Mbeya district, Tanzania. SAC made up 34% of the population and received MDA with praziquantel (40mg/kg) in 2012 (both districts) and in 2013 (Mbozi only). Three cross-sectional population-based surveys were performed in 2012 (R0), 2013 (R1), and 2014 (R2). In each survey approximately 3000 study subjects of all ages were tested for taeniosis using copro-Ag-ELISA. In total 9064 people were tested and copro-Ag-ELISA positive cases were offered treatment 6-8 months after sampling. The copro-Ag prevalence of taeniosis was significantly higher (Χ2-test, p=0.007) in Mbozi (3.0%) at R0 compared to Mbeya (1.5%). Twelve months after MDA in both districts (R1), the copro-Ag prevalence had dropped significantly in both Mbozi (2.0%, p=0.024) and in Mbeya (0.3%, p=0.004), but the significant difference between the districts persisted (Χ2-test, p<0.001). Ten months after the second round of MDA in Mbozi and 22 month after the first MDA (R2), the copro-Ag prevalence had dropped significantly again in Mbozi (0.8%, p<0.001), but had slightly increased in Mbeya (0.5%, p=0.051), with no difference between the two districts (Χ2-test, p=0.51). The taeniosis cases tracked and treated between round R0 and R2 represented 9% of the projected total number of taeniosis cases within the study area, based on the copro-Ag prevalence and village population data. Among SAC in Mbozi, infection significantly decreased at R1 (p=0.004, OR 0.12, CI: 0.02-0.41) and R2 (p=0.001, OR 0.24, CI: 0.09-0.53) when comparing to R0. In Mbeya infection significant decreased at R1 (p=0.013, OR 0.14, CI: 0.02-0.55), but no difference was found for R2 (p=0. 089), when comparing to R0 among SAC. This study showed that school-based MDA with praziquantel in combination with 'track and treat' of taeniosis cases significantly reduced the copro-Ag prevalence of taeniosis, and that annual MDA was significantly better than single MDA. The persistence of taeniosis cases illustrates that a One Health approach must be emphasized for effective control.
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Reprint of "Assessing the impact of a joint human-porcine intervention package for Taenia solium control: Results of a pilot study from northern Lao PDR". Acta Trop 2017; 165:261-267. [PMID: 27887694 DOI: 10.1016/j.actatropica.2016.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/09/2016] [Accepted: 03/13/2016] [Indexed: 11/23/2022]
Abstract
Following confirmation that a remote village of approximately 300 inhabitants in northern Lao PDR was hyperendemic for the Neglected Tropical Disease Taenia solium, a pilot human-porcine therapeutic control intervention was implemented between October 2013 and November 2014. Mass drug administration with a three day albendazole 400mg protocol was offered to all eligible humans in October 2013 and March 2014. At these times, and again in October 2014, eligible village pigs received the anti-cysticercosis TSOL18 vaccination and an oral dose of oxfendazole anthelmintic at 30mg/kg, both repeated one month later. Community and individual human taeniasis prevalences were estimated via copro-antigen ELISA of volunteered human faecal samples prior to October 2013, and again in January 2015, in order to examine the short term impact of the intervention.
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Gabriël S, Dorny P, Mwape KE, Trevisan C, Braae UC, Magnussen P, Thys S, Bulaya C, Phiri IK, Sikasunge CS, Makungu C, Afonso S, Nicolau Q, Johansen MV. Control of Taenia solium taeniasis/cysticercosis: The best way forward for sub-Saharan Africa? Acta Trop 2017; 165:252-260. [PMID: 27140860 DOI: 10.1016/j.actatropica.2016.04.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 04/22/2016] [Accepted: 04/23/2016] [Indexed: 11/15/2022]
Abstract
Taenia solium taeniasis/cysticercosis is a neglected parasitic zoonosis with significant economic and public health impacts. Control measures can be broadly grouped into community health education, improvements in hygiene and sanitary conditions, proper meat handling at household and community level, improved standards of meat inspection, pig management, treatment of individual patients and possibly human populations, and treatment and/or vaccination of porcine populations. This manuscript looks critically into currently existing control options and provides suggestions on which (combination of) tools would be most effective in the control of T. solium taeniasis/cysticercosis in sub-Saharan Africa. Field data and disease transmission simulations suggest that implementation of a single intervention control strategy will not lead to a satisfactory reduction of disease morbidity or transmission. A feasible strategy to combat T. solium taeniasis/cysticercosis would include a combination of approaches focussing on both human (health education and treatment) and animal host (management, treatment and vaccination), which can vary for different communities and different geographical locations. Selection of the specific strategy depends on cost-effectiveness analyses based on solid field data, currently unavailable, though urgently needed; as well as on health priorities and resources of the country. A One Health approach involving medical, veterinary, environmental and social sectors is essential for T. solium to be controlled and eventually eliminated. Finally the success of any intervention is largely dependent on the level of societal and political acceptance, commitment and engagement.
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Affiliation(s)
- S Gabriël
- Institute of Tropical Medicine, Antwerp, Belgium.
| | - P Dorny
- Institute of Tropical Medicine, Antwerp, Belgium; Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - K E Mwape
- School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
| | - C Trevisan
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - U C Braae
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - P Magnussen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - S Thys
- Institute of Tropical Medicine, Antwerp, Belgium
| | - C Bulaya
- School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
| | - I K Phiri
- School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
| | - C S Sikasunge
- School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
| | - C Makungu
- School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
| | - S Afonso
- Faculty of Veterinary Medicine, Eduardo Mondlane University, Maputo, Mozambique
| | - Q Nicolau
- Faculty of Veterinary Medicine, Eduardo Mondlane University, Maputo, Mozambique
| | - M V Johansen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
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Braae UC, Devleesschauwer B, Gabriël S, Dorny P, Speybroeck N, Magnussen P, Torgerson P, Johansen MV. CystiSim - An Agent-Based Model for Taenia solium Transmission and Control. PLoS Negl Trop Dis 2016; 10:e0005184. [PMID: 27984581 PMCID: PMC5161321 DOI: 10.1371/journal.pntd.0005184] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 11/14/2016] [Indexed: 11/19/2022] Open
Abstract
Taenia solium taeniosis/cysticercosis was declared eradicable by the International Task Force for Disease Eradication in 1993, but remains a neglected zoonosis. To assist in the attempt to regionally eliminate this parasite, we developed cystiSim, an agent-based model for T. solium transmission and control. The model was developed in R and available as an R package (http://cran.r-project.org/package=cystiSim). cystiSim was adapted to an observed setting using field data from Tanzania, but adaptable to other settings if necessary. The model description adheres to the Overview, Design concepts, and Details (ODD) protocol and consists of two entities—pigs and humans. Pigs acquire cysticercosis through the environment or by direct contact with a tapeworm carrier's faeces. Humans acquire taeniosis from slaughtered pigs proportional to their infection intensity. The model allows for evaluation of three interventions measures or combinations hereof: treatment of humans, treatment of pigs, and pig vaccination, and allows for customary coverage and efficacy settings. cystiSim is the first agent-based transmission model for T. solium and suggests that control using a strategy consisting of an intervention only targeting the porcine host is possible, but that coverage and efficacy must be high if elimination is the ultimate goal. Good coverage of the intervention is important, but can be compensated for by including an additional intervention targeting the human host. cystiSim shows that the scenarios combining interventions in both hosts, mass drug administration to humans, and vaccination and treatment of pigs, have a high probability of success if coverage of 75% can be maintained over at least a four year period. In comparison with an existing mathematical model for T. solium transmission, cystiSim also includes parasite maturation, host immunity, and environmental contamination. Adding these biological parameters to the model resulted in new insights in the potential effect of intervention measures. Taenia solium is the leading cause of preventable epilepsy and the highest ranking foodborne parasite in terms of disease burden worldwide. Currently there are no large scale control programmes implemented against T. solium, but efficacious intervention tools are there, making control programmes the next step forward. Because of the zoonotic properties of the parasite, existing in both humans and pigs, a combination of intervention tools is likely to be needed. cystiSim is an agent-based disease model that provides insight into which intervention tools, and the frequency of administration of these tools, are needed to yield an effect on disease prevalence. cystiSim is a valuable tool in designing future control programmes and will assist in the elimination of T. solium as a public health problem.
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Affiliation(s)
- Uffe Christian Braae
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
- * E-mail:
| | - Brecht Devleesschauwer
- Department of Public Health and Surveillance, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium
| | - Sarah Gabriël
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Pierre Dorny
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Niko Speybroeck
- Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium
| | - Pascal Magnussen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
- Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Paul Torgerson
- Section of Epidemiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Maria Vang Johansen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
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Braae UC, Magnussen P, Harrison W, Ndawi B, Lekule F, Johansen MV. Effect of National Schistosomiasis Control Programme on Taenia solium taeniosis and porcine cysticercosis in rural communities of Tanzania. Parasite Epidemiol Control 2016; 1:245-251. [PMID: 27695711 PMCID: PMC5034013 DOI: 10.1016/j.parepi.2016.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/26/2016] [Accepted: 08/26/2016] [Indexed: 12/03/2022] Open
Abstract
Taenia solium is found throughout sub-Saharan Africa and co-endemic with schistosomiasis in many regions. Taenia solium leads to taeniosis and neurocysticercosis - the leading cause of preventable epilepsy globally. This study aimed to assess the effects of the National Schistosomiasis Control Programme on prevalence of taeniosis and porcine cysticercosis over a four year period in Tanzania. School-based mass drug administration (MDA) of praziquantel was carried out based on schistosomiasis endemicity. Four human and five porcine cross-sectional surveys were carried out from 2012 to 2015 in Mbozi and Mbeya district in Tanzania. Three rounds of school-based MDA of praziquantel were delivered in Mbozi and two in Mbeya. The prevalence of taeniosis and porcine cysticercosis was estimated annually. Stool samples were collected from humans and prevalence of taeniosis estimated by copro-Ag-ELISA. Blood samples from pigs were collected to estimate cysticercosis prevalence by Ag-ELISA. “Track-and-treat” of taeniosis cases was carried out after each survey. In total 12082 stool samples and 4579 porcine serum samples were collected. Significantly fewer children (≤ 15) from Mbozi were infected throughout the study than children from Mbeya who showed a significant decrease in copro-Ag prevalence after the first treatment only. During the final survey in Mbozi the prevalence of taeniosis in adults (1.8%) was significantly lower (p = 0.031, OR 0.40, CI: 0.17–0.89), compared to baseline (4.1%). The prevalence of porcine cysticercosis (8%) had also dropped significantly (p = 0.002, OR 0.49, CI: 0.32–0.76) in this district compared to baseline (13%), whereas no significant difference was seen in Mbeya compared to baseline. The study suggests that three rounds of MDA targeting schistosomiasis in school-aged children combined with ‘track-and-treat’ contributed to a reduction in prevalence of T. solium in this population, and also had a spillover effect on adults in treated areas as well as reducing the prevalence of T. solium in the intermediate pig host population. Elimination of T. solium in this area would require a One Health approach.
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Affiliation(s)
- Uffe Christian Braae
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark
| | - Pascal Magnussen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; Centre for Medical Parasitology, Faculty of Health of Medical Sciences, University of Copenhagen, DK-1353 Copenhagen, Denmark
| | - Wendy Harrison
- Faculty of Medicine, School of Public Health, Imperial College London, United Kingdom
| | - Benedict Ndawi
- Bora Professional Consultancy Services, Iringa, Tanzania
| | - Faustin Lekule
- Faculty of Agriculture, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Maria Vang Johansen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark
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Okello AL, Thomas L, Inthavong P, Ash A, Khamlome B, Keokamphet C, Newberry K, Gauci CG, Gabriël S, Dorny P, Thompson RCA, Lightowlers MW, Allen J. Assessing the impact of a joint human-porcine intervention package for Taenia solium control: Results of a pilot study from northern Lao PDR. Acta Trop 2016; 159:185-91. [PMID: 26992295 DOI: 10.1016/j.actatropica.2016.03.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/09/2016] [Accepted: 03/13/2016] [Indexed: 11/24/2022]
Abstract
Following confirmation that a remote village of approximately 300 inhabitants in northern Lao PDR was hyperendemic for the Neglected Tropical Disease Taenia solium, a pilot human-porcine therapeutic control intervention was implemented between October 2013 and November 2014. Mass drug administration with a three day albendazole 400mg protocol was offered to all eligible humans in October 2013 and March 2014. At these times, and again in October 2014, eligible village pigs received the anti-cysticercosis TSOL18 vaccination and an oral dose of oxfendazole anthelmintic at 30mg/kg, both repeated one month later. Community and individual human taeniasis prevalences were estimated via copro-antigen ELISA of volunteered human faecal samples prior to October 2013, and again in January 2015, in order to examine the short term impact of the intervention.
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32
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Aung AK, Spelman DW. Taenia solium Taeniasis and Cysticercosis in Southeast Asia. Am J Trop Med Hyg 2016; 94:947-54. [PMID: 26834197 PMCID: PMC4856625 DOI: 10.4269/ajtmh.15-0684] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/15/2015] [Indexed: 12/12/2022] Open
Abstract
Human taeniasis/cysticercosis caused by the pork tapeworm Taenia solium has been identified as a potentially eradicable disease by the International Task Force for Disease Eradication of the World Health Organization. In southeast Asia, T. solium taeniasis/cysticercosis is considered one of the major neglected tropical diseases afflicting the region. In the last few decades, a considerable effort has been invested toward establishing the epidemiology and burden of disease in several southeast Asian countries. Moreover, further evidence is emerging as to understanding the dynamics of disease transmission and cultural, political, and socioeconomic factors influencing the success of control and eradication efforts within the region. However, despite major collaborations by several champion groups, advances have been slow and little remains known about the complete epidemiology of taeniasis/cysticercosis and the barriers to programmatic success. This review article aims to address the above issues with a further focus on the challenges to control and eradicate taeniasis/cysticercosis within the southeast Asia region.
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Affiliation(s)
- Ar Kar Aung
- Department of General Medicine, The Alfred Hospital, Victoria, Australia; Department of Infectious Diseases, The Alfred Hospital, Victoria, Australia; Monash University, Victoria, Australia; Department of Microbiology, The Alfred Hospital, Victoria, Australia
| | - Denis W Spelman
- Department of General Medicine, The Alfred Hospital, Victoria, Australia; Department of Infectious Diseases, The Alfred Hospital, Victoria, Australia; Monash University, Victoria, Australia; Department of Microbiology, The Alfred Hospital, Victoria, Australia
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Abstract
The World Health Organization announced in November 2014 at the fourth international meeting on ‘the control of neglected zoonotic diseases – from advocacy to action’, that intervention tools for eliminating Taenia solium taeniosis/cysticercosis (TSTC) are in place. The aim of this work was to elucidate theoretical outcomes of various control options suggested for TSTC elimination in sub-Saharan Africa (SSA) over a 4-year period. Our current knowledge regarding T. solium epidemiology and control primarily builds on studies from Latin America. A simple transmission model – built on data from Latin America – has been used to predict the effect of various interventions such as mass treatment of humans, vaccination and treatment of pigs, and health education of communities, potentially leading to change in bad practices and reducing transmission risks. Based on simulations of the transmission model, even a 4-year integrated One Health approach fails to eliminate TSTC from a small community and in all simulations, the prevalence of human taeniosis and porcine cysticercosis start to rise as soon as the programmes end. Our current knowledge regarding transmission and burden of TSTC in SSA is scarce and while claiming to be tool ready, the selection of diagnostic and surveillance tools, as well as the algorithms and stepwise approaches for control and elimination of TSTC remain major challenges.
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Coral-Almeida M, Gabriël S, Abatih EN, Praet N, Benitez W, Dorny P. Taenia solium Human Cysticercosis: A Systematic Review of Sero-epidemiological Data from Endemic Zones around the World. PLoS Negl Trop Dis 2015; 9:e0003919. [PMID: 26147942 PMCID: PMC4493064 DOI: 10.1371/journal.pntd.0003919] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/17/2015] [Indexed: 11/24/2022] Open
Abstract
Background Taenia solium cysticercosis is a zoonotic neglected disease responsible for severe health disorders such as seizures and death. Understanding the epidemiology of human cysticercosis (HCC) in endemic regions will help to expose critical information about the transmission of the disease, which could be used to design efficient control programs. This review gathered serological data on apparent prevalence of T. solium circulating antigens and/or seroprevalence of T. solium antibodies, apparent prevalence of human taeniasis and risk factors for HCC from endemic communities in order to understand the differences in exposure to the parasite and active infections with T. solium metacestodes in endemic areas around the world. Methods Three databases were used to search sero-epidemiological data from community-based studies conducted between 1989 and 2014 in cysticercosis endemic communities worldwide. The search focused on data obtained from T. solium circulating antigen detection by monoclonal antibody-based sandwich ELISA and/or T. solium antibody seroprevalence determined by Enzyme-linked Immunoelectrotransfer Blot (EITB). A meta-analysis was performed per continent. Principal Findings A total of 39,271 participants from 19 countries, described in 37 articles were studied. The estimates for the prevalence of circulating T. solium antigens for Africa, Latin America and Asia were: 7.30% (95% CI [4.23–12.31]), 4.08% (95% CI [2.77–5.95]) and 3.98% (95% CI [2.81–5.61]), respectively. Seroprevalence estimates of T. solium antibodies were 17.37% (95% CI [3.33–56.20]), 13.03% (95% CI [9.95–16.88]) and 15.68% (95% CI [10.25–23.24]) respectively. Taeniasis reported prevalences ranged from 0 (95% CI [0.00–1.62]) to 17.25% (95% CI [14.55–20.23]). Significance A significant variation in the sero-epidemiological data was observed within each continent, with African countries reporting the highest apparent prevalences of active infections. Intrinsic factors in the human host such as age and immunity were main determinants for the occurrence of infections, while exposure was mostly related to environmental factors which varied from community to community. Human cysticercosis is a neglected zoonotic disease caused by the larval stage of the parasite Taenia solium. This disease is responsible for severe health disorders such as seizures, and in some cases even death. T. solium cysticercosis is endemic in countries in Africa, Latin America and Asia where conditions such as inadequate hygiene, poor sanitary conditions, open defecation, free roaming pigs and poverty permit the transmission of the disease. Diagnostic tools are capable of detecting exposure to eggs and infection levels in a population through antibody and antigen detection, respectively. This review focused on gathering epidemiological data from endemic communities in Africa, Latin America and Asia in order to understand the causes of the observed variations in exposure/infection patterns in endemic regions. Similar antibody seroprevalences were observed worldwide while infection prevalences varied significantly within each region. Intrinsic factors such as age and immunity were determining factors for the occurrence of infections, while exposure was related to environmental factors which varied from region to region. Understanding the epidemiology of cysticercosis in endemic regions will help expose information on the transmission, which could in turn be used to design appropriate control programs.
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Affiliation(s)
- Marco Coral-Almeida
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
- Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
- Universidad Central del Ecuador, Centro Internacional de Zoonosis (CIZ), Ciudadela Universitaria, Quito, Ecuador
- Universidad de las Américas, Escuela de Medicina Veterinaria y Zootecnia, Quito, Ecuador
- * E-mail:
| | - Sarah Gabriël
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
| | - Emmanuel Nji Abatih
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
| | - Nicolas Praet
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
| | - Washington Benitez
- Universidad Central del Ecuador, Centro Internacional de Zoonosis (CIZ), Ciudadela Universitaria, Quito, Ecuador
- Universidad Central del Ecuador, Facultad de Medicina Veterinaria y Zootecnia, Ciudadela Universitaria, Quito, Ecuador
| | - Pierre Dorny
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
- Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
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Braae UC, Saarnak CFL, Mukaratirwa S, Devleesschauwer B, Magnussen P, Johansen MV. Taenia solium taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa. Parasit Vectors 2015; 8:323. [PMID: 26065414 PMCID: PMC4465723 DOI: 10.1186/s13071-015-0938-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/05/2015] [Indexed: 12/03/2022] Open
Abstract
Background This study aimed to map the distribution of Taenia solium taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa. These two major neglected tropical diseases are presumed to be widely distributed in Africa, but currently the level of co-distribution is unclear. Methods A literature search on T. solium taeniosis/cysticercosis was performed to compile all known studies on the presence of T. solium and apparent prevalence of taeniosis and porcine cysticercosis in Africa. Studies were geo-referenced using an online gazetteer. A Bayesian framework was used to combine the epidemiological data on the apparent prevalence with external information on test characteristics to estimate informed district-level prevalence of taeniosis and porcine cysticercosis. Districts with T. solium taeniosis/cysticercosis presence were cross-referenced with the Global Neglected Tropical Diseases Database for schistosomiasis presence. Results The search strategies identified 141 reports of T. solium in Africa from 1985 to 2014 from a total of 476 districts in 29 countries, 20 with porcine cysticercosis, 22 with human cysticercosis, and 16 with taeniosis, in addition to 2 countries identified from OIE reports. All 31 countries were considered, on national scale, to have co-distribution with schistosomiasis. Presence of both parasites was confirmed in 124 districts in 17 countries. The informed prevalence of taeniosis and porcine cysticercosis were estimated for 14 and 41 districts in 10 and 13 countries, respectively. Conclusions With the paucity of data, T. solium infection is grossly under-reported and expected to be more widespread than this study suggests. In areas where co-distribution occurs there is a need for increased emphasis on evaluation of integrated intervention approaches for these two helminth infections and allocation of resources for evaluating the extent of adverse effects caused by mass drug administration. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-0938-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Uffe Christian Braae
- Department of Veterinary Disease Biology, Section for Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark.
| | - Christopher F L Saarnak
- Department of Veterinary Disease Biology, Section for Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark.
| | - Samson Mukaratirwa
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa.
| | - Brecht Devleesschauwer
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium. .,Institute of Health and Society (IRSS), Université catholique de Louvain, 1200, Brussels, Belgium.
| | - Pascal Magnussen
- Department of Veterinary Disease Biology, Section for Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark. .,Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1353, Copenhagen, Denmark.
| | - Maria Vang Johansen
- Department of Veterinary Disease Biology, Section for Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark.
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Braae UC, Magnussen P, Lekule F, Harrison W, Johansen MV. Temporal fluctuations in the sero-prevalence of Taenia solium cysticercosis in pigs in Mbeya Region, Tanzania. Parasit Vectors 2014; 7:574. [PMID: 25471610 PMCID: PMC4266939 DOI: 10.1186/s13071-014-0574-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 11/26/2014] [Indexed: 11/15/2022] Open
Abstract
Background Porcine cysticercosis is an emerging agricultural problem in sub-Saharan Africa. This has been documented primarily through cross-sectional studies, however detailed knowledge of the transmission dynamics of this disease in sub-Saharan Africa is lacking. This study aims to describe seasonal variations in sero-prevalence of antigen ELISA positive porcine cysticercosis in an endemic area. Methods A longitudinal study composed of three cross-sectional surveys was carried out in Mbeya Region, Tanzania; the first two six months apart (March/April 2012 and October/November 2012) and the last eight months later (July/August 2013). Venous blood was collected from pigs in 22 villages and analysed using Ag-ELISA. Results In each survey between 800–1000 serum samples were collected. The first survey revealed a cysticercosis sero-prevalence of 15% (n = 822, 95% CI: 13-18%). The sero-prevalence had significantly increased to 24% (p < 0.001, χ2-test, n = 812, 95% CI: 21-27%) at the time of the 6 month follow-up. At 14-months the sero-prevalence had dropped to 20% (p = 0.053, χ2-test, n = 998, 95% CI: 18-23%). Overall, this was a reduction in sero-prevalence compared with a study conducted in 2007 in the same area, where 31% (186/600) of pigs were found positive. Conclusion Confined pigs did not have a lower sero-prevalence compared to free roaming pigs in any of the three surveys. Several factors may have contributed to the observed fluctuations such as African swine fever or seasonal variation in local crop production practices. Also, as the Ag-ELISA assay used is not species specific, variation in transmission of Taenia hydatigena could potentially influence the results. The observed fluctuations contradict a theoretical model which predicts a stable equilibrium, which only considers a two-compartment (pig and human) model excluding the effect of the environment. Whether the disease has an endemic equilibrium, or undergoes fluctuations dependent on extrinsic and/or socio-economic factors remains to be elucidated.
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Affiliation(s)
- Uffe Christian Braae
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark.
| | - Pascal Magnussen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark. .,Institute for International Health, Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, DK-1353, Copenhagen, Denmark.
| | - Faustin Lekule
- Faculty of Agriculture, Sokoine University of Agriculture, Morogoro, Tanzania.
| | - Wendy Harrison
- Faculty of Medicine, School of Public Health, Imperial College London, London, UK.
| | - Maria Vang Johansen
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg, Denmark.
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Carabin H, Traoré AA. Taenia solium taeniasis and cysticercosis control and elimination through community-based interventions. CURRENT TROPICAL MEDICINE REPORTS 2014; 1:181-193. [PMID: 25544938 DOI: 10.1007/s40475-014-0029-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Taenia solium was declared potentially eradicable by the International Task Force for Disease Eradication in 1992. Yet, very few well-designed community-based randomized controlled trials have been conducted to measure the effectiveness of alternative control strategies. Most strategies have been tested in pre-post intervention designs in very few communities, often without a control group. The only two community-based randomized controlled trials suggest that an educational program alone or a combination of human and porcine mass treatment reduce porcine cysticercosis in the short term. A transmission dynamics model suggests that improved sanitation and pig management are more effective and sustainable than pig vaccination, human or porcine mass treatment. Current evidence does not support the eradication of Taenia solium in the foreseeable future. Investigators should follow international recommendations on the conduct of community-based randomized control trials to provide more valid estimates of the effect and cost-effectiveness of alternative control strategies for cysticercosis.
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Affiliation(s)
- Hélène Carabin
- Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104
| | - Aminata A Traoré
- Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104. Tel: 405 271-2229.
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Bardosh K, Inthavong P, Xayaheuang S, Okello AL. Controlling parasites, understanding practices: the biosocial complexity of a One Health intervention for neglected zoonotic helminths in northern Lao PDR. Soc Sci Med 2014; 120:215-23. [PMID: 25261615 DOI: 10.1016/j.socscimed.2014.09.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 09/15/2014] [Accepted: 09/16/2014] [Indexed: 11/25/2022]
Abstract
A parasitological survey in northern Lao PDR showed a remote ethnic minority village to be hyper-endemic for Taenia solium, a Neglected Tropical Disease (NTD) that impacts human and pig health. An intervention combining human Mass Drug Administration (MDA) with porcine vaccination and antihelmintic treatment was then implemented, targeting both T. solium and other soil-transmitted helminths. To understand the biosocial complexity of this integrated One Health intervention, we conducted a rapid ethnographic study exploring the transmission dynamics of T. solium and locally acceptable long-term control options. Informed by two years of project work in the village, this included six focus group discussions, 35 semi-structured interviews, a latrine survey, a school-based education meeting, participant observation and many unstructured interviews conducted over two weeks in October 2013. We found that risk behaviours were mediated by various social determinants including limited market access, interrelationships between alcohol, ancestral sacrifices and the consumption of raw pork, seasonal variations and poor latrine coverage. Only sixteen percent of households had latrines, attributed to the unacceptability of dry latrines, lack of water access, poor building techniques and poverty. Whilst women could explain T. solium transmission, most men and children could not, revealing that distributed posters/leaflets relied too heavily on text and ambiguous images. Compliance with MDA was high due to trust between project staff and village leaders. However understandings of pharmacology, minor side effects, human migration and children's fear of worms may lead to resistance in future programmes. Our research highlights the complexities of controlling T. solium and other soil-transmitted helminths in a remote ethnic minority village and the need to integrate biomedical and participatory approaches. Although we showcase the heuristic value of using rapid ethnography to inform intervention strategies as part of a One Health/NTD agenda, we also identify several possible paradoxes and conundrums in embedding locally-grounded biosocial analysis into NTD programmes. These need to be acknowledged and negotiated by multidisciplinary teams.
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Affiliation(s)
- Kevin Bardosh
- School of Social and Political Science, The University of Edinburgh, 58 George Square, Edinburgh, United Kingdom; Division of Pathway Medicine and Centre for Infectious Diseases, School of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom.
| | - Phouth Inthavong
- National Animal Health Laboratory, Ministry of Agriculture and Forestry, Department of Livestock and Fisheries, Luang Prabang Road, Ban Huanmouang, Vientiane Capital, Lao Democratic People's Republic
| | - Sivilai Xayaheuang
- CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory (AAHL) Regional Programme, 5 Portarlington Road, East Geelong, Victoria, Australia
| | - Anna L Okello
- National Animal Health Laboratory, Ministry of Agriculture and Forestry, Department of Livestock and Fisheries, Luang Prabang Road, Ban Huanmouang, Vientiane Capital, Lao Democratic People's Republic; CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory (AAHL) Regional Programme, 5 Portarlington Road, East Geelong, Victoria, Australia
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Johansen MV, Trevisan C, Braae UC, Magnussen P, Ertel RL, Mejer H, Saarnak CF. The Vicious Worm: a computer-based Taenia solium education tool. Trends Parasitol 2014; 30:372-4. [DOI: 10.1016/j.pt.2014.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 06/15/2014] [Accepted: 06/19/2014] [Indexed: 11/29/2022]
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Coral-Almeida M, Rodríguez-Hidalgo R, Celi-Erazo M, García HH, Rodríguez S, Devleesschauwer B, Benítez-Ortiz W, Dorny P, Praet N. Incidence of human Taenia solium larval Infections in an Ecuadorian endemic area: implications for disease burden assessment and control. PLoS Negl Trop Dis 2014; 8:e2887. [PMID: 24852050 PMCID: PMC4031064 DOI: 10.1371/journal.pntd.0002887] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 04/10/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Human cysticercosis is a zoonotic disease causing severe health disorders and even death. While prevalence data become available worldwide, incidence rate and cumulative incidence figures are lacking, which limits the understanding of the Taenia solium epidemiology. METHODOLOGY/PRINCIPAL FINDINGS A seroepidemiological cohort study was conducted in a south-Ecuadorian community to estimate the incidence rate of infection with and the incidence rate of exposure to T. solium based on antigen and antibody detections, respectively. The incidence rate of infection was 333.6 per 100,000 person-years (95% CI: [8.4-1,858] per 100,000 person-years) contrasting with a higher incidence rate of exposure 13,370 per 100,000 person-years (95% CI: [8,730-19,591] per 100,000 person-years). The proportion of infected individuals remained low and stable during the whole study year while more than 25% of the population showed at least one antibody seroconversion/seroreversion during the same time period. CONCLUSIONS/SIGNIFICANCE Understanding the transmission of T. solium is essential to develop ad hoc cost-effective prevention and control programs. The estimates generated here may now be incorporated in epidemiological models to simulate the temporal transmission of the parasite and the effects of control interventions on its life cycle. These estimates are also of high importance to assess the disease burden since incidence data are needed to make regional and global projections of morbidity and mortality related to cysticercosis.
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Affiliation(s)
- Marco Coral-Almeida
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
- Universidad Central del Ecuador, Centro Internacional de Zoonosis (CIZ), Ciudadela Universitaria, Quito, Ecuador
- Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
- * E-mail:
| | - Richar Rodríguez-Hidalgo
- Universidad Central del Ecuador, Facultad de Medicina Veterinaria y Zootecnia, Ciudadela Universitaria, Quito, Ecuador
- Universidad Central del Ecuador, Núcleo de Investigadores, Ciudadela Universitaria, Quito, Ecuador
| | - Maritza Celi-Erazo
- Universidad Central del Ecuador, Centro Internacional de Zoonosis (CIZ), Ciudadela Universitaria, Quito, Ecuador
| | - Héctor Hugo García
- Universidad Peruana Cayetano Heredia, Lima, Perú
- Instituto Nacional de Ciencias Neurológicas, Lima, Perú
| | | | - Brecht Devleesschauwer
- Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
- Université catholique de Louvain, Institute of Health and Society, Brussels, Belgium
| | - Washington Benítez-Ortiz
- Universidad Central del Ecuador, Centro Internacional de Zoonosis (CIZ), Ciudadela Universitaria, Quito, Ecuador
- Universidad Central del Ecuador, Facultad de Medicina Veterinaria y Zootecnia, Ciudadela Universitaria, Quito, Ecuador
| | - Pierre Dorny
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
- Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
| | - Nicolas Praet
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
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Parija SC, Gireesh A. Cysticercus cellulosae antigens in the serodiagnosis of neurocysticercosis. Trop Parasitol 2013; 1:64-72. [PMID: 23508242 PMCID: PMC3593475 DOI: 10.4103/2229-5070.86932] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 10/31/2011] [Indexed: 11/04/2022] Open
Abstract
Neurocysticercosis (NCC) is difficult to diagnose clinically because of its varied clinical presentation. However, an accurate diagnosis is possible only after suspicion on epidemiological grounds, proper interpretation of the clinical data, analysis of the findings on imaging studies, and specific immunological tests on the serum and cerebrospinal fluid (CSF). The diagnosis of NCC by any single parameter thus continues to remain difficult. In the past, detection of NCC was based on autopsy studies and histological confirmation. In recent times, the advent of imaging methods such as computed tomography and magnetic resonance imaging have provided excellent non-invasive tools for easy detection of NCC. Nevertheless, an imaging technique of the brain, although useful, is not considered as a gold standard for the diagnosis of NCC. Serological tests are being increasingly used in adjunct with imaging techniques, to aid the diagnosis of NCC. Immunodiagnostic techniques include detection methods for specific antibodies and for circulating parasite antigens in the serum and CSF. Currently, many of the immunodiagnostic tests, including the enzyme-linked immunosorbent assay and enzyme immunotransfer blot, use purified native antigens for the immunodiagnosis of NCC. Nevertheless, the main problem with the use of native cysticercal antigens is that the native proteins often show cross reactions with sera from humans infected with other parasites. The preparation of native antigens also demand a constant supply of parasitic material from the intermediate host pig. In order to overcome the problems in using native antigens, the recombinant antigens or synthetic peptides, which can be produced under stable conditions, are being evaluated for the serodiagnosis of NCC.
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Affiliation(s)
- Subhash Chandra Parija
- Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India
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Gilman RH, Gonzalez AE, Llanos-Zavalaga F, Tsang VCW, Garcia HH. Prevention and control of Taenia solium taeniasis/cysticercosis in Peru. Pathog Glob Health 2013; 106:312-8. [PMID: 23265557 DOI: 10.1179/2047773212y.0000000045] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Taenia solium is endemic in most of the world, causing seizures and other neurological symptoms. Transmission is mainly maintained in rural areas by a human to pig cycle. Despite claims on its eradicability, sustainable interruption of transmission has not yet been reported. This manuscript reviews the conceptual basis for control, available diagnostic and control tools, and recent experiences on control in the field performed in Peru along the past decade.
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Affiliation(s)
- Robert H Gilman
- Department of Microbiology, and Center for Global Health-Tumbes, Universidad Peruana Cayetano Heredia, Lima, Peru
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Pondja A, Neves L, Mlangwa J, Afonso S, Fafetine J, Willingham AL, Thamsborg SM, Johansen MV. Use of oxfendazole to control porcine cysticercosis in a high-endemic area of Mozambique. PLoS Negl Trop Dis 2012; 6:e1651. [PMID: 22666509 PMCID: PMC3362632 DOI: 10.1371/journal.pntd.0001651] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 04/08/2012] [Indexed: 11/18/2022] Open
Abstract
A randomized controlled field trial to evaluate the effectiveness of a single oral dose of 30 mg/kg of oxfendazole (OFZ) treatment for control of porcine cysticercosis was conducted in 4 rural villages of Angónia district, north-western Mozambique. Two hundred and sixteen piglets aged 4 months were selected and assigned randomly to OFZ treatment or control groups. Fifty-four piglets were treated at 4 months of age (T1), while another 54 piglets were treated at 9 months of age (T2) and these were matched with 108 control pigs from the same litters and raised under the same conditions. Baseline data were collected on the prevalence of porcine cysticercosis using antigen ELISA (Ag-ELISA), as well as knowledge and practices related to Taenia solium transmission based on questionnaire interviews and observations. All animals were followed and re-tested for porcine cysticercosis by Ag-ELISA at 9 and 12 months of age when the study was terminated. Overall prevalence at baseline was 5.1% with no significant difference between groups. At the end of the study, 66.7% of the controls were found positive, whereas 21.4% of the T1 and 9.1% of the T2 pigs were positive, respectively. Incidence rates of porcine cysticercosis were lower in treated pigs as compared to controls. Necropsy of 30 randomly selected animals revealed that viable cysts were present in none (0/8) of T2 pigs, 12.5% (1/8) of T1 pigs and 42.8% (6/14) of control pigs. There was a significant reduction in the risk of T. solium cysticercosis if pigs were treated with OFZ either at 4 months (OR = 0.14; 95% CI: 0.05-0.36) or at 9 months of age (OR = 0.05; 95% CI: 0.02-0.16). Strategic treatment of pigs in endemic areas should be further explored as a means to control T. solium cysticercosis/taeniosis.
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Affiliation(s)
- Alberto Pondja
- Faculty of Veterinary Medicine, Eduardo Mondlane University, Maputo, Mozambique.
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Short Communication: In Vitro Efficacy Testing of Praziquantel, Ivermectin, and Oxfendazole against Taenia Solium Cysts. J Parasitol Res 2011; 2012:363276. [PMID: 21785697 PMCID: PMC3135050 DOI: 10.1155/2012/363276] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Accepted: 04/01/2011] [Indexed: 11/23/2022] Open
Abstract
Oxfendazole is recommended as the drug of choice for treating porcine cysticercosis. The drug does not kill brain cysts and is not registered for use in pigs. Latest its safety in the recommended dose has been questioned. The aim of this study was to investigate two alternative anthelminthics. The efficacy of praziquantel and ivermectin was compared to oxfendazole In Vitro on Taenia solium. Cysts of T. solium were isolated from infected pork and incubated in culture media together with the drugs. The degree of evagination was used as effect measurement and determined after 6 hours.
Praziquantel had a half maximal effective concentration (EC50) of value 0.006 ± 0.001 μg/mL. Ivermectin did not show any impact on the evagination in concentrations from 0.001 to 30 μg/mL and neither did oxfendazole in concentrations from 0.001 to 50 μg/mL.
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Abstract
Sustained research efforts over the last 50 years have revealed a considerable amount of information about immunity to taeniid cestode infections in the parasites’ intermediate hosts. As a product of this research, a series of effective recombinant vaccines have been developed which have no parallel in any other group of parasitic organisms. There are, however, many important aspects relating to immunity that remain to be elucidated. Some concepts have come to be firmly held as facts and yet the supportive data are either conflicting or unconfirmed. This review considers the phenomenon of immunity to re-infection with taeniid cestodes in their intermediate hosts, examining carefully the nature of the evidence that is available to support conclusions that have been drawn in this area.
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Affiliation(s)
- M W Lightowlers
- Faculty of Veterinary Science, The University of Melbourne, Werribee, Victoria, Australia.
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46
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Assana E, Gauci CG, Kyngdon CT, Zoli AP, Dorny P, Geerts S, Lightowlers MW. Antibody responses to the host-protective Taenia solium oncosphere protein TSOL18 in pigs are directed against conformational epitopes. Parasite Immunol 2010; 32:399-405. [PMID: 20500670 PMCID: PMC2881308 DOI: 10.1111/j.1365-3024.2009.01197.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TSOL18 is a recombinant protein that has been shown in repeated experimental trials to be capable of protecting pigs against challenge infection with the cestode parasite Taenia solium. Antibodies raised by the vaccine are capable of killing the parasite in an in vitroculture and it is believed that antibody and complement-mediated killing of invading parasites is the major protective immune mechanism induced by vaccination with TSOL18. Investigations were undertaken to characterize whether the principal antibody specificities raised by TSOL18 in pigs were against linear or conformational determinants. TSOL18 was expressed in two truncated forms representing either the amino terminal portion or the carboxy terminal portion, with the two truncations overlapping in sequence by 25 amino acids. The original protein (designated TSOL18N−) and the two truncations (TSOL18N−-1 and TSOL18N−-2) were used in inhibition ELISA. TSOL18N− was shown to be capable of completely inhibiting the binding of pig anti-TSOL18N− antibodies to TSOL18N− in ELISA. However, neither TSOL18N−-1 nor TSOL18N−-2, either alone or when combined together, was capable of inhibiting any detectable amount of reactivity of pig anti-TSOL18N− antibodies with TSOL18N−. It is concluded that the dominant antibody specificities, and probably the host-protective specificities, of TSOL18 are conformational epitopes.
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Affiliation(s)
- E Assana
- Department of Animal Health, Prince Leopold Institute of Tropical Medicine, Antwerpen, Belgium
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47
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Conlan JV, Vongxay K, Fenwick S, Blacksell SD, Thompson RA. Does interspecific competition have a moderating effect on Taenia solium transmission dynamics in Southeast Asia? Trends Parasitol 2009; 25:398-403. [DOI: 10.1016/j.pt.2009.06.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 06/02/2009] [Accepted: 06/05/2009] [Indexed: 11/26/2022]
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48
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A health-education intervention trial to reduce porcine cysticercosis in Mbulu District, Tanzania. Prev Vet Med 2008; 85:52-67. [DOI: 10.1016/j.prevetmed.2007.12.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 12/07/2007] [Accepted: 12/25/2007] [Indexed: 11/23/2022]
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49
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Pawlowski ZS. Control of neurocysticercosis by routine medical and veterinary services. Trans R Soc Trop Med Hyg 2007; 102:228-32. [PMID: 18054057 DOI: 10.1016/j.trstmh.2007.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 10/16/2007] [Accepted: 10/16/2007] [Indexed: 11/29/2022] Open
Abstract
Taenia solium neurocysticercosis and ocular cysticercosis are two of the most devastating parasitic infections, which need to be controlled for medical and economic reasons. This paper discusses why control measures are not implemented adequately in endemic areas and proposes simple operational interventions, based on focus-oriented chemotherapy of T. solium taeniasis using existing health care infrastructure and improved collaboration between medical and veterinary services. These interventions can be quickly and easily implemented (irrespective of other applicable control measures), with medical and veterinary staff being adequately trained, and safe, effective and cheap taenicides made available.
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