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Molla J, Sekkak I, Mundo Ortiz A, Moyles I, Nasri B. Mathematical modeling of mpox: A scoping review. One Health 2023; 16:100540. [PMID: 37138928 PMCID: PMC10108573 DOI: 10.1016/j.onehlt.2023.100540] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 04/04/2023] [Accepted: 04/11/2023] [Indexed: 05/05/2023] Open
Abstract
Background Mpox (monkeypox), a disease historically endemic to Africa, has seen its largest outbreak in 2022 by spreading to many regions of the world and has become a public health threat. Informed policies aimed at controlling and managing the spread of this disease necessitate the use of adequate mathematical modeling strategies. Objective In this scoping review, we sought to identify the mathematical models that have been used to study mpox transmission in the literature in order to determine what are the model classes most frequently used, their assumptions, and the modelling gaps that need to be addressed in the context of the epidemiological characteristics of the ongoing mpox outbreak. Methods This study employed the methodology of the PRISMA guidelines for scoping reviews to identify the mathematical models available to study mpox transmission dynamics. Three databases (PubMed, Web of Science and MathSciNet) were systematically searched to identify relevant studies. Results A total of 5827 papers were screened from the database queries. After the screening, 35 studies that met the inclusion criteria were analyzed, and 19 were finally included in the scoping review. Our results show that compartmental, branching process, Monte Carlo (stochastic), agent-based, and network models have been used to study mpox transmission dynamics between humans as well as between humans and animals. Furthermore, compartmental and branching models have been the most commonly used classes. Conclusions There is a need to develop modeling strategies for mpox transmission that take into account the conditions of the current outbreak, which has been largely driven by human-to-human transmission in urban settings. In the current scenario, the assumptions and parameters used by most of the studies included in this review (which are largely based on a limited number of studies carried out in Africa in the early 80s) may not be applicable, and therefore, can complicate any public health policies that are derived from their estimates. The current mpox outbreak is also an example of how more research into neglected zoonoses is needed in an era where new and re-emerging diseases have become global public health threats.
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Affiliation(s)
- Jeta Molla
- Department of Mathematics and Statistics, York University, Toronto, Canada
| | - Idriss Sekkak
- Département de médecine sociale et préventive, École de Santé Publique de l'Université de Montréal, Montréal, Canada
- Centre de recherche en santé publique, Université de Montréal, Montréal, Canada
| | - Ariel Mundo Ortiz
- Département de médecine sociale et préventive, École de Santé Publique de l'Université de Montréal, Montréal, Canada
- Centre de Recherches Mathématiques, Université de Montréal, Montréal, Canada
- Centre de recherche en santé publique, Université de Montréal, Montréal, Canada
| | - Iain Moyles
- Department of Mathematics and Statistics, York University, Toronto, Canada
| | - Bouchra Nasri
- Département de médecine sociale et préventive, École de Santé Publique de l'Université de Montréal, Montréal, Canada
- Centre de Recherches Mathématiques, Université de Montréal, Montréal, Canada
- Centre de recherche en santé publique, Université de Montréal, Montréal, Canada
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Banuet-Martinez M, Yang Y, Jafari B, Kaur A, Butt ZA, Chen HH, Yanushkevich S, Moyles IR, Heffernan JM, Korosec CS. Monkeypox: a review of epidemiological modelling studies and how modelling has led to mechanistic insight. Epidemiol Infect 2023; 151:e121. [PMID: 37218612 PMCID: PMC10468816 DOI: 10.1017/s0950268823000791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023] Open
Abstract
Human monkeypox (mpox) virus is a viral zoonosis that belongs to the Orthopoxvirus genus of the Poxviridae family, which presents with similar symptoms as those seen in human smallpox patients. Mpox is an increasing concern globally, with over 80,000 cases in non-endemic countries as of December 2022. In this review, we provide a brief history and ecology of mpox, its basic virology, and the key differences in mpox viral fitness traits before and after 2022. We summarize and critique current knowledge from epidemiological mathematical models, within-host models, and between-host transmission models using the One Health approach, where we distinguish between models that focus on immunity from vaccination, geography, climatic variables, as well as animal models. We report various epidemiological parameters, such as the reproduction number, R0, in a condensed format to facilitate comparison between studies. We focus on how mathematical modelling studies have led to novel mechanistic insight into mpox transmission and pathogenesis. As mpox is predicted to lead to further infection peaks in many historically non-endemic countries, mathematical modelling studies of mpox can provide rapid actionable insights into viral dynamics to guide public health measures and mitigation strategies.
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Affiliation(s)
- Marina Banuet-Martinez
- Climate Change and Global Health Research Group, School of Public Health, University of Alberta, Edmonton, AB, Canada
| | - Yang Yang
- School of Public Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Behnaz Jafari
- Mathematics and Statistics Department, Faculty of Science, University of Calgary, Calgary, AB, Canada
- Department of Biomedical Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Avneet Kaur
- Irving K. Barber School of Arts and Sciences, Department of Computer Science, Mathematics, Physics and Statistics, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Zahid A. Butt
- School of Public Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Helen H. Chen
- School of Public Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Svetlana Yanushkevich
- Department of Biomedical Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Iain R. Moyles
- Modelling Infection and Immunity Lab, Mathematics and Statistics, York University, Toronto, ON, Canada
- Centre for Disease Modelling, Mathematics and Statistics, York University, Toronto, ON, Canada
| | - Jane M. Heffernan
- Modelling Infection and Immunity Lab, Mathematics and Statistics, York University, Toronto, ON, Canada
- Centre for Disease Modelling, Mathematics and Statistics, York University, Toronto, ON, Canada
| | - Chapin S. Korosec
- Modelling Infection and Immunity Lab, Mathematics and Statistics, York University, Toronto, ON, Canada
- Centre for Disease Modelling, Mathematics and Statistics, York University, Toronto, ON, Canada
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Ko Y, Mendoza VM, Mendoza R, Seo Y, Lee J, Jung E. Estimation of monkeypox spread in a nonendemic country considering contact tracing and self-reporting: A stochastic modeling study. J Med Virol 2023; 95:e28232. [PMID: 36254095 DOI: 10.1002/jmv.28232] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 01/11/2023]
Abstract
In May 2022, monkeypox started to spread in nonendemic countries. To investigate contact tracing and self-reporting of the primary case in the local community, a stochastic model is developed. An algorithm based on Gillespie's stochastic chemical kinetics is used to quantify the number of infections, contacts, and duration from the arrival of the primary case to the detection of the index case (or until there are no more local infections). Different scenarios were set considering the delay in contact tracing and behavior of infectors. We found that the self-reporting behavior of a primary case is the most significant factor affecting outbreak size and duration. Scenarios with a self-reporting primary case have an 86% reduction in infections (average: 5-7, in a population of 10 000) and contacts (average: 27-72) compared with scenarios with a non-self-reporting primary case (average number of infections and contacts: 27-72 and 197-537, respectively). Doubling the number of close contacts per day is less impactful compared with the self-reporting behavior of the primary case as it could only increase the number of infections by 45%. Our study emphasizes the importance of the prompt detection of the primary case.
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Affiliation(s)
- Youngsuk Ko
- Department of Mathematics, Konkuk University, Seoul, South Korea
| | - Victoria May Mendoza
- Department of Mathematics, Konkuk University, Seoul, South Korea.,Institute of Mathematics, University of the Philippines Diliman, Quezon City, Philippines
| | - Renier Mendoza
- Department of Mathematics, Konkuk University, Seoul, South Korea.,Institute of Mathematics, University of the Philippines Diliman, Quezon City, Philippines
| | - Yubin Seo
- Department of Internal Medicine, Division of Infectious Disease, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
| | - Jacob Lee
- Department of Internal Medicine, Division of Infectious Disease, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
| | - Eunok Jung
- Department of Mathematics, Konkuk University, Seoul, South Korea
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Augsburger IB, Galanthay GK, Tarosky JH, Rychtář J, Taylor D. Voluntary vaccination may not stop monkeypox outbreak: A game-theoretic model. PLoS Negl Trop Dis 2022; 16:e0010970. [PMID: 36516113 DOI: 10.1371/journal.pntd.0010970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/21/2022] [Indexed: 12/15/2022] Open
Abstract
Monkeypox (MPX) is a viral zoonotic disease that was endemic to Central and West Africa. However, during the first half of 2022, MPX spread to almost 60 countries all over the world. Smallpox vaccines are about 85% effective in preventing MPX infections. Our objective is to determine whether the vaccines should be mandated or whether voluntary use of the vaccine could be enough to stop the MPX outbreak. We incorporate a standard SVEIR compartmental model of MPX transmission into a game-theoretical framework. We study a vaccination game in which individuals decide whether or not to vaccinate by assessing their benefits and costs. We solve the game for Nash equilibria, i.e., the vaccination rates the individuals would likely adopt without any outside intervention. We show that, without vaccination, MPX can become endemic in previously non-endemic regions, including the United States. We also show that to "not vaccinate" is often an optimal solution from the individual's perspective. Moreover, we demonstrate that, for some parameter values, there are multiple equilibria of the vaccination game, and they exhibit a backward bifurcation. Thus, without centrally mandated minimal vaccination rates, the population could easily revert to no vaccination scenario.
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Affiliation(s)
- Ian B Augsburger
- Department of Applied Mathematics and Statistics, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Grace K Galanthay
- Department of Mathematics and Computer Science, College of the Holy Cross, Worcester, Massachusetts, United States of America
| | - Jacob H Tarosky
- Department of Mathematical Sciences, High Point University, High Point, North Carolina, United States of America
| | - Jan Rychtář
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Dewey Taylor
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Kadaleka S, Abelman S, Tchuenche JM. A Human-Bovine Schistosomiasis Mathematical Model with Treatment and Mollusciciding. Acta Biotheor 2021; 69:511-541. [PMID: 34191204 DOI: 10.1007/s10441-021-09416-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
To mitigate the spread of schistosomiasis, a deterministic human-bovine mathematical model of its transmission dynamics accounting for contaminated water reservoirs, including treatment of bovines and humans and mollusciciding is formulated and theoretically analyzed. The disease-free equilibrium is locally and globally asymptotically stable whenever the basic reproduction number [Formula: see text], while global stability of the endemic equilibrium is investigated by constructing a suitable Lyapunov function. To support the analytical results, parameter values from published literature are used for numerical simulations and where applicable, uncertainty analysis on the non-dimensional system parameters is performed using the Latin Hypercube Sampling and Partial Rank Correlation Coefficient techniques. Sensitivity analysis to determine the relative importance of model parameters to disease transmission shows that the environment-related parameters namely, [Formula: see text] (snails shedding rate of cercariae), [Formula: see text] (probability that cercariae shed by snails survive), c (fraction of the contaminated environment sprayed by molluscicides) and [Formula: see text] (mortality rate of cercariae) are the most significant to mitigate the spread of schistosomiasis. Mollusciciding, which directly impacts the contaminated environment as a single control strategy is more effective compared to treatment. However, concurrently applying mollusciciding and treatment will yield a better outcome.
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Zhou W, Xiao Y, Heffernan JM. A two-thresholds policy to interrupt transmission of West Nile Virus to birds. J Theor Biol 2018; 463:22-46. [PMID: 30550862 DOI: 10.1016/j.jtbi.2018.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 11/15/2022]
Abstract
This paper proposes a model of West Nile Virus (WNV) including threshold control policies concerning the culling of mosquitoes and birds under different conditions. Two thresholds are introduced to estimate whether and which control strategy should be implemented. For each mosquito threshold level [Formula: see text] the dynamical behaviour of the proposed non-smooth system is investigated as the bird threshold level [Formula: see text] varies, focusing on the existence of sliding domains, the existence of pseudo-equilibria, real or virtual of the endemic equilibria, global stability of these steady states, and the most interesting case of the occurrence of a novel globally asymptotically stable pseudo-attractor. The model solutions ultimately converge to a real equilibrium or a pseudo-equilibrium (if it exists), or a pseudo-attractor if no equilibrium is real and no pseudo-equilibrium exists. Here within, we show that the free system has a single stable endemic equilibrium under biologically reasonable assumptions, and show that when the control system has: (1) a bird-culling threshold that is above the bird equilibrium, culling has no advantage; (2) a bird-culling threshold that is below the bird equilibrium, but a mosquito-culling threshold that lies above the mosquito equilibrium, the infected bird population can be reduced but the infected mosquito population will remain the same; (3) a bird-culling threshold and a mosquito-culling threshold that both lie below their respective equilibrium values of the free system, then both the infected bird and mosquito populations can be reduced to lower levels. The results suggest that preset levels of the number of infected birds and infected mosquitoes can be maintained simultaneously when threshold values are chosen properly, which provides a possible control strategy when an emergent infectious disease cannot be eradicated immediately.
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Affiliation(s)
- Weike Zhou
- Department of Applied Mathematics, School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, PR China.
| | - Yanni Xiao
- Department of Applied Mathematics, School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, PR China.
| | - Jane M Heffernan
- Department of Mathematics & Statistics, York University, Toronto, ON, M3J 1P3, Canada.
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Chamchod F. Modeling the spread of capripoxvirus among livestock and optimal vaccination strategies. J Theor Biol 2018; 437:179-186. [DOI: 10.1016/j.jtbi.2017.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 09/01/2017] [Accepted: 10/08/2017] [Indexed: 12/01/2022]
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