scholarly journals Validation of a spatial agent-based model for Taenia solium transmission (“CystiAgent”) against a large prospective trial of control strategies in northern Peru

2021 ◽  
Vol 15 (10) ◽  
pp. e0009885
Author(s):  
Ian W. Pray ◽  
Francesco Pizzitutti ◽  
Gabrielle Bonnet ◽  
Eloy Gonzalez-Gustavson ◽  
Wayne Wakeland ◽  
...  
Keyword(s):  
Taenia Solium ◽  
Prospective Trial ◽  
World Health ◽  
Transmission Model ◽  
Agent Based Model ◽  
Agent Based ◽  
Targeted Interventions ◽  
Porcine Cysticercosis ◽  
The World ◽  
Northern Peru

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.

scholarly journals Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model

2020 ◽  
Author(s):  
Ian Wright Pray ◽  
Wayne Wakeland ◽  
William Pan ◽  
William E. Lambert ◽  
Hector H. Garcia ◽  
...  
Keyword(s):  
Taenia Solium ◽  
Model Performance ◽  
Rank Correlation ◽  
Public Health Problem ◽  
Sensitivity Analyses ◽  
Transmission Model ◽  
Spatially Explicit ◽  
Model Parameters ◽  
Agent Based Model ◽  
Agent Based

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 .

scholarly journals Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model

2020 ◽  
Author(s):  
Ian Wright Pray ◽  
Wayne Wakeland ◽  
William Pan ◽  
William E. Lambert ◽  
Hector H. Garcia ◽  
...  
Keyword(s):  
Taenia Solium ◽  
Model Performance ◽  
Rank Correlation ◽  
Public Health Problem ◽  
Sensitivity Analyses ◽  
Transmission Model ◽  
Spatially Explicit ◽  
Model Parameters ◽  
Agent Based Model ◽  
Agent Based

Abstract BackgroundThe 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. MethodsWe 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. ResultsLHS-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.ConclusionsCystiAgent 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.

scholarly journals Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model

2020 ◽  
Author(s):  
Ian Wright Pray ◽  
Wayne Wakeland ◽  
William Pan ◽  
William E. Lambert ◽  
Hector H. Garcia ◽  
...  
Keyword(s):  
Taenia Solium ◽  
Model Performance ◽  
Rank Correlation ◽  
Public Health Problem ◽  
Sensitivity Analyses ◽  
Transmission Model ◽  
Spatially Explicit ◽  
Model Parameters ◽  
Agent Based Model ◽  
Agent Based

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.

scholarly journals Are we ready for Taenia solium cysticercosis elimination in sub-Saharan Africa?

Parasitology ◽  
2016 ◽  
Vol 144 (1) ◽  
pp. 59-64 ◽  
Author(s):  
MARIA VANG JOHANSEN ◽  
CHIARA TREVISAN ◽  
SARAH GABRIËL ◽  
PASCAL MAGNUSSEN ◽  
UFFE CHRISTIAN BRAAE
Keyword(s):  
Latin America ◽  
Current Knowledge ◽  
Taenia Solium ◽  
Sub Saharan Africa ◽  
World Health ◽  
Transmission Model ◽  
Small Community ◽  
Porcine Cysticercosis ◽  
Sub Saharan ◽  
Health Organization

SUMMARYThe 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.

scholarly journals A Spatial Agent-Based Model to Assess the Spread of Malaria in Relation to Anti-Malaria Interventions in Southeast Iran

2020 ◽  
Vol 9 (9) ◽  
pp. 549
Author(s):  
Navid Mahdizadeh Gharakhanlou ◽  
Navid Hooshangi ◽  
Marco Helbich
Keyword(s):  
Indoor Residual Spraying ◽  
Intervention Strategies ◽  
Agent Based Model ◽  
Malaria Endemic Area ◽  
High Coverage ◽  
Agent Based ◽  
The World ◽  
Coverage Rates ◽  
Long Lasting Insecticidal Nets ◽  
Malaria Interventions

Malaria threatens the lives of many people throughout the world. To counteract its spread, knowledge of the prevalence of malaria and the effectiveness of intervention strategies is of great importance. The aim of this study was to assess (1) the spread of malaria by means of a spatial agent-based model (ABM) and (2) the effectiveness of several interventions in controlling the spread of malaria. We focused on Sarbaz county in Iran, a malaria-endemic area where the prevalence rate is high. Our ABM, which was carried out in two steps, considers humans and mosquitoes along with their attributes and behaviors as agents, while the environment is made up of diverse environmental factors, namely air temperature, relative humidity, vegetation, altitude, distance from rivers and reservoirs, and population density, the first three of which change over time. As control interventions, we included long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). The simulation results showed that applying LLINs and IRS in combination, rather than separately, was most efficient in reducing the number of infected humans. In addition, LLINs and IRS with moderate or high and high coverage rates, respectively, had significant effects on reducing the number of infected humans when applied separately. Our results can assist health policymakers in selecting appropriate intervention strategies in Iran to reduce malaria transmission.

scholarly journals CystiSim – An Agent-Based Model for Taenia solium Transmission and Control

2016 ◽  
Vol 10 (12) ◽  
pp. e0005184 ◽  
Author(s):  
Uffe Christian Braae ◽  
Brecht Devleesschauwer ◽  
Sarah Gabriël ◽  
Pierre Dorny ◽  
Niko Speybroeck ◽  
...  
Keyword(s):  
Taenia Solium ◽  
Agent Based Model ◽  
Agent Based ◽  
And Control

scholarly journals Agent-based modeling of persons who inject drugs in metropolitan Chicago suggests that re-treatment with antivirals of persons who are re-infected with Hep C is critical to achieve the WHO incidence reduction objective by 2030

2019 ◽  
Author(s):  
Eric Tatara ◽  
Alexander Gutfraind ◽  
Nicholson T. Collier ◽  
Scott J. Cotler ◽  
Marian Major ◽  
...  
Keyword(s):  
Scale Up ◽  
Treatment Strategies ◽  
Agent Based Modeling ◽  
World Health ◽  
Persons Who Inject Drugs ◽  
Agent Based ◽  
Direct Acting Antiviral ◽  
The World ◽  
Health Organization ◽  
Direct Acting

ABSTRACTHepatitis C (HCV) is a leading cause of chronic liver disease and mortality worldwide. Persons who inject drugs (PWID) are at the highest risk for acquiring and transmitting HCV infection. We developed an agent-based model (ABM) to identify and optimize direct-acting antiviral (DAA) therapy scale-up and treatment strategies for achieving the World Health Organization (WHO) goals of HCV elimination by the year 2030. DAA is highly efficacious, but may require re-treatment particularly among PWID who at risk for reinfection after cure. Using an ABM approach, we predict that this prohibition will jeopardize achieving the WHO’s goal of reducing 90% of HCV incidence by 2030. We found that DAA scale-up rates of greater than or equal to 5% per year can achieve the WHO target of 90% incidence reduction. Our model simulations underscore the importance of DAA scale-up that includes re-treatment of re-infected individuals in order to achieve significant reductions in incidence.FUNDINGThis research is supported by NIH grant R01GM121600.

scholarly journals The World Health Organization 2030 goals for Taenia solium: Insights and perspectives from transmission dynamics modelling

2019 ◽  
Vol 3 ◽  
pp. 1546 ◽  
Author(s):  
Keyword(s):  
World Health Organization ◽  
Taenia Solium ◽  
Sub Saharan Africa ◽  
Transmission Dynamics ◽  
World Health ◽  
Sustainable Solutions ◽  
The World ◽  
Health Organization ◽  
The Impact ◽  
Transmission Models

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.

scholarly journals Control of Taenia solium taeniasis/cysticercosis: past practices and new possibilities

Parasitology ◽  
2013 ◽  
Vol 140 (13) ◽  
pp. 1566-1577 ◽  
Author(s):  
MARSHALL W. LIGHTOWLERS
Keyword(s):  
Taenia Solium ◽  
Global Burden ◽  
Intermediate Hosts ◽  
Research Attention ◽  
Major Health ◽  
Porcine Cysticercosis ◽  
Health Burden ◽  
Limited Success ◽  
The World ◽  
Control Programmes

SUMMARYNeurocysticercosis continues to be a major health burden on humans living in many regions of the world, despite the availability of highly effective taeniacides and identification of the cause, Taenia solium, as being potentially eradicable. Several T. solium control trials have been undertaken, generally achieving limited success and none that has been fully documented has achieved what was demonstrated to be a sustainable level of disease control. Pigs act as intermediate hosts for T. solium and two new control tools have become available for application in pigs – single-dose oxfendazole treatment of porcine cysticercosis and the TSOL18 vaccine. Three potential intervention scenarios for pigs are compared for control of cysticercosis, using either oxfendazole or vaccination. A control scenario involving vaccination plus oxfendazole treatment delivered at 4 monthly intervals was predicted to achieve the best outcome, with no pigs slaughtered at 12 months of age having viable T. solium cysticerci. Now that new control tools are available, there are opportunities to concentrate research attention on evaluation of novel control scenarios leading to the implementation of effective and sustainable control programmes and a reduction in the global burden of neurocysticercosis.

scholarly journals COVID-19 outbreak and control in Kenya- Insights from a mathematical model

2021 ◽  
Author(s):  
Rachel Waema Mbogo ◽  
Titus Okello Orwa
Keyword(s):  
Reproduction Number ◽  
Control Measures ◽  
Capital City ◽  
World Health ◽  
Transmission Model ◽  
Global Public Health ◽  
The World ◽  
Rate Of Recovery ◽  
Health Organization ◽  
And Control

Abstract The coronavirus disease 2019 (COVID-19) pandemic reached Kenya in March 2020 with the initial cases reported in the capital city Nairobi and in the coastal area Mombasa. As reported by the World Health Organization, the outbreak of COVID-19 has spread across the world, killed many, collapsed economies and changed the way people live since it was first reported in Wuhan, China, in the end of 2019. As of May 25,2020 It had led to over 100,000 confirmed cases in Africa with over 3000 deaths. The trend poses a huge threat to global public health. Understanding the early transmission dynamics of the infection and evaluating the effectiveness of control measures is crucial for assessing the potential for sustained transmission to occur in new areas.We employed a SEIHCRD mathematical transmission model with reported Kenyan data on cases of COVID-19 to estimate how transmission varies over time. The model is concise in structure, and successfully captures the course of the COVID-19 outbreak, and thus sheds light on understanding the trends of the outbreak. The next generation matrix approach was adopted to calculate the basic reproduction number (R0) from the model to assess the factors driving the infection . The results from the model analysis shows that non-pharmaceutical interventions over a relatively long period is needed to effectively get rid of the COVID-19 epidemic otherwise the rate of infection will continue to increase despite the increased rate of recovery.

Sign in / Sign up

Export Citation Format

Share Document