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Wheeler J, Rosengart A, Jiang Z, Tan K, Treutle N, Ionides EL. Informing policy via dynamic models: Cholera in Haiti. PLoS Comput Biol 2024; 20:e1012032. [PMID: 38683863 PMCID: PMC11081515 DOI: 10.1371/journal.pcbi.1012032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 05/09/2024] [Accepted: 03/29/2024] [Indexed: 05/02/2024] Open
Abstract
Public health decisions must be made about when and how to implement interventions to control an infectious disease epidemic. These decisions should be informed by data on the epidemic as well as current understanding about the transmission dynamics. Such decisions can be posed as statistical questions about scientifically motivated dynamic models. Thus, we encounter the methodological task of building credible, data-informed decisions based on stochastic, partially observed, nonlinear dynamic models. This necessitates addressing the tradeoff between biological fidelity and model simplicity, and the reality of misspecification for models at all levels of complexity. We assess current methodological approaches to these issues via a case study of the 2010-2019 cholera epidemic in Haiti. We consider three dynamic models developed by expert teams to advise on vaccination policies. We evaluate previous methods used for fitting these models, and we demonstrate modified data analysis strategies leading to improved statistical fit. Specifically, we present approaches for diagnosing model misspecification and the consequent development of improved models. Additionally, we demonstrate the utility of recent advances in likelihood maximization for high-dimensional nonlinear dynamic models, enabling likelihood-based inference for spatiotemporal incidence data using this class of models. Our workflow is reproducible and extendable, facilitating future investigations of this disease system.
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Affiliation(s)
- Jesse Wheeler
- Statistics Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - AnnaElaine Rosengart
- Statistics and Data Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Zhuoxun Jiang
- Statistics Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kevin Tan
- Wharton Statistics and Data Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Noah Treutle
- Statistics Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Edward L. Ionides
- Statistics Department, University of Michigan, Ann Arbor, Michigan, United States of America
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Chowdhury F, Aziz AB, Ahmmed F, Ahmed T, Kang SS, Im J, Park J, Tadesse BT, Islam MT, Kim DR, Hoque M, Pak G, Khanam F, McMillan NAJ, Liu X, Zaman K, Khan AI, Kim JH, Marks F, Qadri F, Clemens JD. The interplay between WASH practices and vaccination with oral cholera vaccines in protecting against cholera in urban Bangladesh: Reanalysis of a cluster-randomized trial. Vaccine 2023; 41:2368-2375. [PMID: 36898931 PMCID: PMC10102718 DOI: 10.1016/j.vaccine.2023.02.054] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 02/06/2023] [Accepted: 02/16/2023] [Indexed: 03/11/2023]
Abstract
The current global initiative to end Cholera by 2030 emphasizes the use of oral cholera vaccine (OCV) combined with feasible household Water-Sanitation-Hygiene (WASH) interventions. However, little is known about how improved WASH practices and behaviors and OCV interact to reduce the risk of cholera. We reanalyzed two arms of a cluster-randomized trial in urban Bangladesh, to evaluate the effectiveness of OCV given as a 2-dose regimen. One arm (30 clusters, n = 94,675) was randomized to vaccination of persons aged one year and older with OCV, and the other arm (30 clusters, n = 80,056) to no intervention. We evaluated the prevention of cholera by household WASH, classified at baseline using a previously validated rule, and OCV over 2 years of follow-up. When analyzed by assignment to OCV clusters rather than receipt of OCV, in comparison to persons living in "Not Better WASH" households in the control clusters, reduction of severe cholera (the primary outcome) was similar for persons in "Not Better WASH" households in vaccine clusters (46%, 95% CI:24,62), for persons in "Better WASH" households in the control clusters (48%, 95% CI:25,64), and for persons in "Better WASH" households in the vaccine clusters (48%, 95% CI:16,67). In contrast, when analyzed by actual receipt of a complete OCV regimen, , in comparison to persons in "Not Better WASH" households in the control clusters, protection against severe cholera increased steadily from 39% (95% CI:13,58) in residents of "Better WASH" households in the control clusters to 57% (95% CI:35,72) in vaccinated persons in "Not Better WASH" households to 63% (95% CI:21,83) in vaccinated persons in "Better WASH" households. This analysis suggests that improved household WASH and OCV received may interact to provide greater protection against cholera. However, the divergence between findings related to intent to vaccinate versus those pertaining to actual receipt of OCV underscores the need for further research on this topic.
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Affiliation(s)
- Fahima Chowdhury
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh; Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
| | | | - Faisal Ahmmed
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Tasnuva Ahmed
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Sophie Sy Kang
- International Vaccine Institute, Seoul, Republic of Korea
| | - Justin Im
- International Vaccine Institute, Seoul, Republic of Korea
| | - Juyeon Park
- International Vaccine Institute, Seoul, Republic of Korea; Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | | | - Md Taufiqul Islam
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Deok Ryun Kim
- International Vaccine Institute, Seoul, Republic of Korea
| | - Masuma Hoque
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Gideok Pak
- International Vaccine Institute, Seoul, Republic of Korea
| | - Farhana Khanam
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Nigel A J McMillan
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Xinxue Liu
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Khalequ Zaman
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Ashraful Islam Khan
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Jerome H Kim
- International Vaccine Institute, Seoul, Republic of Korea
| | - Florian Marks
- International Vaccine Institute, Seoul, Republic of Korea; Department of Medicine, University of Cambridge, Cambridge, United Kingdom; University of Antananarivo, Antananarivo, Madagascar
| | - Firdausi Qadri
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - John D Clemens
- International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh; International Vaccine Institute, Seoul, Republic of Korea; UCLA Fielding School of Public Health, Los Angeles, CA 90095-1772, USA
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Wang J. Mathematical Models for Cholera Dynamics-A Review. Microorganisms 2022; 10:microorganisms10122358. [PMID: 36557611 PMCID: PMC9783556 DOI: 10.3390/microorganisms10122358] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/27/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022] Open
Abstract
Cholera remains a significant public health burden in many countries and regions of the world, highlighting the need for a deeper understanding of the mechanisms associated with its transmission, spread, and control. Mathematical modeling offers a valuable research tool to investigate cholera dynamics and explore effective intervention strategies. In this article, we provide a review of the current state in the modeling studies of cholera. Starting from an introduction of basic cholera transmission models and their applications, we survey model extensions in several directions that include spatial and temporal heterogeneities, effects of disease control, impacts of human behavior, and multi-scale infection dynamics. We discuss some challenges and opportunities for future modeling efforts on cholera dynamics, and emphasize the importance of collaborations between different modeling groups and different disciplines in advancing this research area.
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Affiliation(s)
- Jin Wang
- Department of Mathematics, University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA
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Elias Chitio JJ, Baltazar CS, Langa JP, Baloi LD, Mboane RBJ, Manuel JA, Assane S, Omar A, Manso M, Capitine I, Van Rensburg C, Luiz N, Mogasale V, Marks F, Park SE, Beck NS. Pre-emptive oral cholera vaccine (OCV) mass vaccination campaign in Cuamba District, Niassa Province, Mozambique: feasibility, vaccination coverage and delivery costs using CholTool. BMJ Open 2022; 12:e053585. [PMID: 36547726 PMCID: PMC9454037 DOI: 10.1136/bmjopen-2021-053585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
INTRODUCTION Mozambique suffers from regular floods along its principal river basins and periodic cyclones that resulted in several cholera epidemics during the last decades. Cholera outbreaks in the recent 5 years affected particularly the northern provinces of the country including Nampula and Niassa provinces. A pre-emptive oral cholera vaccine (OCV) mass vaccination campaign was conducted in Cuamba District, Niassa Province, and the feasibility, costs, and vaccination coverage assessed. METHODS WHO prequalified OCV (Euvichol-Plus), a killed whole-cell bivalent vaccine containing Vibrio cholerae O1 (classical and El Tor) and O139, was administered in two doses with a 15-day interval during 7-31 August 2018, targeting around 180 000 people aged above 1 year in Cuamba District. Microplanning, community sensitisation, and training of local public health professionals and field enumerators were conducted. Feasibility and costs of vaccination were assessed using CholTool. Vaccination coverage and barriers were assessed through community surveys. RESULTS The administrative coverage of the first and second rounds of the campaign were 98.9% (194 581) and 98.8% (194 325), respectively, based on the available population data that estimated total 196 652 inhabitants in the target area. The vaccination coverage survey exhibited 75.9% (±2.2%) and 68.5% (±3.3%) coverage for the first and second rounds, respectively. Overall, 60.4% (±3.4%) of the target population received full two doses of OCV. Barriers to vaccination included incompatibility between working hours and campaign time. No severe adverse events were notified. The total financial cost per dose delivered was US$0.60 without vaccine cost and US$1.98 including vaccine costs. CONCLUSION The pre-emptive OCV mass vaccination campaign in remote setting in Mozambique was feasible with reasonable full-dose vaccination coverage to confer sufficient herd immunity for at least the next 3 to 5 years. The delivery cost estimate indicates that the OCV campaign is affordable as it is comparable with Gavi's operational support for vaccination campaigns.
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Affiliation(s)
- Jucunú J Elias Chitio
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
| | - Cynthia S Baltazar
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
| | - José Paulo Langa
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
| | - Liliana Dengo Baloi
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
| | | | | | - Sadate Assane
- Provincial Directorate of Health, Lichinga City, Mozambique
| | - Alide Omar
- District Health Directorate, Cuamba District, Mozambique
| | - Mariana Manso
- District Health Directorate, Cuamba District, Mozambique
| | - Igor Capitine
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
| | - Craig Van Rensburg
- Policy and Economic Research Department, International Vaccine Institute, Seoul, Republic of Korea
| | - Naira Luiz
- National Department for Surveillance and Surveys in Health, National Institute of Health, Maputo, Mozambique
- Clinical, Assessment, Regulatory, Evaluation (CARE) Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Vittal Mogasale
- Policy and Economic Research Department, International Vaccine Institute, Seoul, Republic of Korea
| | - Florian Marks
- Epidemology, Public Health, Impact (EPIC) Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Se Eun Park
- Clinical, Assessment, Regulatory, Evaluation (CARE) Unit, International Vaccine Institute, Seoul, Republic of Korea
- Yonsei University Graduate School of Public Health, Seoul, Republic of Korea
| | - Namseon S Beck
- Clinical, Assessment, Regulatory, Evaluation (CARE) Unit, International Vaccine Institute, Seoul, Republic of Korea
- Medair Headquarters, Ecublens, VD, Switzerland
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Janoušková E, Clark J, Kajero O, Alonso S, Lamberton PHL, Betson M, Prada JM. Public Health Policy Pillars for the Sustainable Elimination of Zoonotic Schistosomiasis. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.826501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Schistosomiasis is a parasitic disease acquired through contact with contaminated freshwater. The definitive hosts are terrestrial mammals, including humans, with some Schistosoma species crossing the animal-human boundary through zoonotic transmission. An estimated 12 million people live at risk of zoonotic schistosomiasis caused by Schistosoma japonicum and Schistosoma mekongi, largely in the World Health Organization’s Western Pacific Region and in Indonesia. Mathematical models have played a vital role in our understanding of the biology, transmission, and impact of intervention strategies, however, these have mostly focused on non-zoonotic Schistosoma species. Whilst these non-zoonotic-based models capture some aspects of zoonotic schistosomiasis transmission dynamics, the commonly-used frameworks are yet to adequately capture the complex epi-ecology of multi-host zoonotic transmission. However, overcoming these knowledge gaps goes beyond transmission dynamics modelling. To improve model utility and enhance zoonotic schistosomiasis control programmes, we highlight three pillars that we believe are vital to sustainable interventions at the implementation (community) and policy-level, and discuss the pillars in the context of a One-Health approach, recognising the interconnection between humans, animals and their shared environment. These pillars are: (1) human and animal epi-ecological understanding; (2) economic considerations (such as treatment costs and animal losses); and (3) sociological understanding, including inter- and intra-human and animal interactions. These pillars must be built on a strong foundation of trust, support and commitment of stakeholders and involved institutions.
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Graveleau J, Reserva ME, Keita A, Molinari R, Constantin De Magny G. Influence of Community-Led Total Sanitation and Water Coverages in the Control of Cholera in Madarounfa, Niger (2018). Front Public Health 2021; 9:643079. [PMID: 33996720 PMCID: PMC8118121 DOI: 10.3389/fpubh.2021.643079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/24/2021] [Indexed: 11/13/2022] Open
Abstract
Every year, cholera affects 1.3-4.0 million people worldwide with a particularly high presence in Africa. Based on recent studies, effective targeting interventions in hotspots could eliminate up to 50% of cases in Sub-Saharan Africa. Those interventions include Water, Sanitation, and Hygiene (WASH) programs whose influence on cholera control, up to the present, has been poorly quantified. Among the few studies available, D'Mello-Guyett et al. underline how the distribution of hygiene kits is a promising form of intervention for cholera control and that the integration of a WASH intervention at the point of admission of suspected cases is new in cholera control efforts, particularly in outbreaks and complex emergencies. Considering the limited number of studies on Community-Led Total Sanitation (CLTS) and water coverages related to cholera control, the aim of our work is to determine whether these interventions in cholera hotspots (geographic areas vulnerable to disease transmission) have significant impact on cholera transmission. In this study, we consider data collected on 125 villages of the Madarounfa district (Niger) during the 2018 cholera outbreak. Using a hurdle model, our findings show that full access to improved sanitation significantly decreases the likelihood of cholera by 91% (P < 0.0001) compared to villages with no access to sanitation at all. Considering only the villages affected by cholera in the studied area, cholera cases decrease by a factor of 4.3 in those villages where there is partial access to at least quality water sources, while full access to improved water sources decreases the cholera cases by a factor of 6.3 when compared to villages without access to water (P < 0.001). In addition, villages without access to safe water and sanitation are 6.7 times (P < 0.0001) more likely to get cholera. Alternatively, villages with full sanitation and water coverage are 9.1 (P < 0.0001) less likely to get cholera. The findings of our study suggest that significant access to improved water and sanitation at the village level offer a strong barrier against cholera transmission. However, it requires full CLTS coverage of the village to observe a strong impact on cholera, as partial access only has a limited impact.
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Affiliation(s)
| | - Maria Eleanor Reserva
- Health Systems Strengthening Unit-Health Section, West and Central Africa Regional Office, UNICEF, Dakar, Senegal
| | | | - Roberto Molinari
- Department of Mathematics and Statistics, Auburn University, Auburn, AL, United States
| | - Guillaume Constantin De Magny
- Centre for Research on the Ecology and Evolution of Diseases (CREES), Montpellier, France.,MIVEGEC (Université de Montpellier, UMR CNRS 5290, IRD 229), Institut de Recherche pour le Développement Délégation Occitanie, Montpellier, France
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Lee EC, Chao DL, Lemaitre JC, Matrajt L, Pasetto D, Perez-Saez J, Finger F, Rinaldo A, Sugimoto JD, Halloran ME, Longini IM, Ternier R, Vissieres K, Azman AS, Lessler J, Ivers LC. Achieving coordinated national immunity and cholera elimination in Haiti through vaccination: a modelling study. Lancet Glob Health 2020; 8:e1081-e1089. [PMID: 32710864 PMCID: PMC7738665 DOI: 10.1016/s2214-109x(20)30310-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 02/17/2020] [Accepted: 05/06/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND Cholera was introduced into Haiti in 2010. Since then, more than 820 000 cases and nearly 10 000 deaths have been reported. Oral cholera vaccine (OCV) is safe and effective, but has not been seen as a primary tool for cholera elimination due to a limited period of protection and constrained supplies. Regionally, epidemic cholera is contained to the island of Hispaniola, and the lowest numbers of cases since the epidemic began were reported in 2019. Hence, Haiti may represent a unique opportunity to eliminate cholera with OCV. METHODS In this modelling study, we assessed the probability of elimination, time to elimination, and percentage of cases averted with OCV campaign scenarios in Haiti through simulations from four modelling teams. For a 10-year period from January 19, 2019, to Jan 13, 2029, we compared a no vaccination scenario with five OCV campaign scenarios that differed in geographical scope, coverage, and rollout duration. Teams used weekly department-level reports of suspected cholera cases from the Haiti Ministry of Public Health and Population to calibrate the models and used common vaccine-related assumptions, but other model features were determined independently. FINDINGS Among campaigns with the same vaccination coverage (70% fully vaccinated), the median probability of elimination after 5 years was 0-18% for no vaccination, 0-33% for 2-year campaigns focused in the two departments with the highest historical incidence, 0-72% for three-department campaigns, and 35-100% for nationwide campaigns. Two-department campaigns averted a median of 12-58% of infections, three-department campaigns averted 29-80% of infections, and national campaigns averted 58-95% of infections. Extending the national campaign to a 5-year rollout (compared to a 2-year rollout), reduced the probability of elimination to 0-95% and the proportion of cases averted to 37-86%. INTERPRETATION Models suggest that the probability of achieving zero transmission of Vibrio cholerae in Haiti with current methods of control is low, and that bolder action is needed to promote elimination of cholera from the region. Large-scale cholera vaccination campaigns in Haiti would offer the opportunity to synchronise nationwide immunity, providing near-term population protection while improvements to water and sanitation promote long-term cholera elimination. FUNDING Bill & Melinda Gates Foundation, Global Good Fund, Institute for Disease Modeling, Swiss National Science Foundation, and US National Institutes of Health.
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Affiliation(s)
- Elizabeth C Lee
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | - Joseph C Lemaitre
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Laura Matrajt
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Damiano Pasetto
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Venice, Italy
| | - Javier Perez-Saez
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Flavio Finger
- Centre for Mathematical Modelling of Infectious Diseases and Department for Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jonathan D Sugimoto
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - M Elizabeth Halloran
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA; Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Ira M Longini
- Department of Biostatistics, College of Public Health and Health Professions, and Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Ralph Ternier
- Partners In Health/Zanmi Lasante, Port-au-Prince, Haiti
| | | | - Andrew S Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Louise C Ivers
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA; Center for Global Health, Massachusetts General Hospital, Boston, MA, USA.
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LUPICA ANTONELLA, GUMEL ABBAB, PALUMBO ANNUNZIATA. THE COMPUTATION OF REPRODUCTION NUMBERS FOR THE ENVIRONMENT-HOST-ENVIRONMENT CHOLERA TRANSMISSION DYNAMICS. J BIOL SYST 2020. [DOI: 10.1142/s021833902040001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study presents a new model for the environment-host-environment transmission dynamics of V. cholerae in a community with an interconnected aquatic pond–river water network. For the case when the human host is the sole target of anti-cholera control and the volume of water in the pond is maximum, the disease-free equilibrium of the model is shown to be globally asymptotically stable whenever a certain epidemiological threshold, known as the basic reproduction number [Formula: see text], is less than unity. The epidemiological implication of this result is that cholera can be eliminated from the community if the control strategies implemented can bring (and maintain) [Formula: see text] to a value less than unity. Four scenarios, that represent different interpretations of the role of the V. cholerea pathogen within the environment, were studied. The corresponding basic reproduction numbers were shown to exhibit the same threshold property with respect to the value unity (i.e., if one is less (equal, greater) than unity, then the three others are also less (equal, greater) than unity. Further, it was shown that for the case where anti-cholera control is focused on the human host population, the associated type reproduction number of the model (corresponding to each of the four transmission scenarios considered) is unique. The implication of this result is that the estimate of the effort needed for disease elimination (i.e., the required herd immunity threshold) is unique, regardless of which of the four transmission scenarios is considered. However, when any of the other two bacterial population types in the aquatic environment (i.e., bacterial in the pond or river) is the focus of the control efforts, this study shows that the associated type reproduction number is not unique. Extensive numerical simulations of the model, using a realistic set of parameters from the published literature, show that the community-wide implementation of a strategy that focus on improved water quality, sanitation, and hygiene (known as WASH-only strategy), using the current estimated coverage of 50% and efficacy of 60%, is unable to lead to the elimination of the disease. Such elimination is attainable if the coverage and efficacy are increased (e.g., to 80% and 90%, respectively). Further, elimination can be achieved using a strategy that focuses on oral rehydration therapy and the use of antibiotics to treat the infected humans (i.e., treatment-only strategy) for moderate effectiveness and coverage levels. The combined hybrid WASH-treatment strategy provides far better population-level impact vis a vis disease elimination. This study ranks the three interventions in the following order of population-level effectiveness: combined WASH-treatment, followed by treatment-only and then WASH-only strategy.
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Affiliation(s)
- ANTONELLA LUPICA
- Department of Mathematics and Computer Sciences, University of Catania, V.le A. Doria 6, 95125 Catania, Italy
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, V.le F. D’Alcontres 31, 98166 Messina, Italy
| | - ABBA B. GUMEL
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, Arizona, USA
- Department of Mathematics and Applied Mathematics, University of Pretoria, Pretoria 0002, South Africa
| | - ANNUNZIATA PALUMBO
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, V.le F. D’Alcontres 31, 98166 Messina, Italy
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Havumaki J, Meza R, Phares CR, Date K, Eisenberg MC. Comparing alternative cholera vaccination strategies in Maela refugee camp: using a transmission model in public health practice. BMC Infect Dis 2019; 19:1075. [PMID: 31864298 PMCID: PMC6925891 DOI: 10.1186/s12879-019-4688-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 12/08/2019] [Indexed: 12/11/2022] Open
Abstract
Background Cholera is a major public health concern in displaced-person camps, which often contend with overcrowding and scarcity of resources. Maela, the largest and longest-standing refugee camp in Thailand, located along the Thai-Burmese border, experienced four cholera outbreaks between 2005 and 2010. In 2013, a cholera vaccine campaign was implemented in the camp. To assist in the evaluation of the campaign and planning for subsequent campaigns, we developed a mathematical model of cholera in Maela. Methods We formulated a Susceptible-Infectious-Water-Recovered-based transmission model and estimated parameters using incidence data from 2010. We next evaluated the reduction in cases conferred by several immunization strategies, varying timing, effectiveness, and resources (i.e., vaccine availability). After the vaccine campaign, we generated case forecasts for the next year, to inform on-the-ground decision-making regarding whether a booster campaign was needed. Results We found that preexposure vaccination can substantially reduce the risk of cholera even when <50% of the population is given the full two-dose series. Additionally, the preferred number of doses per person should be considered in the context of one vs. two dose effectiveness and vaccine availability. For reactive vaccination, a trade-off between timing and effectiveness was revealed, indicating that it may be beneficial to give one dose to more people rather than two doses to fewer people, given that a two-dose schedule would incur a delay in administration of the second dose. Forecasting using realistic coverage levels predicted that there was no need for a booster campaign in 2014 (consistent with our predictions, there was not a cholera epidemic in 2014). Conclusions Our analyses suggest that vaccination in conjunction with ongoing water sanitation and hygiene efforts provides an effective strategy for controlling cholera outbreaks in refugee camps. Effective preexposure vaccination depends on timing and effectiveness. If a camp is facing an outbreak, delayed distribution of vaccines can substantially alter the effectiveness of reactive vaccination, suggesting that quick distribution of vaccines may be more important than ensuring every individual receives both vaccine doses. Overall, this analysis illustrates how mathematical models can be applied in public health practice, to assist in evaluating alternative intervention strategies and inform decision-making.
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Affiliation(s)
- Joshua Havumaki
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, 48109, MI, USA
| | - Rafael Meza
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, 48109, MI, USA
| | - Christina R Phares
- US Centers for Disease Control and Prevention; National Center for Emerging and Zoonotic Infectious Diseases; Division of Global Migration and Quarantine and Prevention, 1600 Clifton Road, Atlanta, 30329, GA, USA
| | - Kashmira Date
- US Centers for Disease Control and Prevention; Global Immunization Division - Center for Global Health, 1600 Clifton Road, Atlanta, 30329, GA, USA
| | - Marisa C Eisenberg
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, 48109, MI, USA.
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Guillaume Y, Raymond M, Jerome GJ, Ternier R, Ivers LC. 'It was a ravage!': lived experiences of epidemic cholera in rural Haiti. BMJ Glob Health 2019; 4:e001834. [PMID: 31798994 PMCID: PMC6861088 DOI: 10.1136/bmjgh-2019-001834] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/11/2019] [Accepted: 09/21/2019] [Indexed: 11/03/2022] Open
Abstract
Introduction A cholera epidemic began in Haiti over 8 years ago, prompting numerous, largely quantitative research studies. Assessments of local 'knowledge, attitudes and practices' relevant for cholera control have relied primarily on cross-sectional surveys. The voices of affected Haitians have rarely been elevated in the scientific literature on the topic. Methods We undertook focus groups with stakeholders in the Artibonite region of Haiti in 2011, as part of planning for a public health intervention to control cholera at the height of the epidemic. In this study, we coded and analysed themes from 55 community members in five focus groups, focusing on local experiences of cholera and responses to the prevention messages. Results The majority of participants had a personal experience with cholera and described its spread in militaristic terms, as a disease that 'attacked' individuals, 'ravaged' communities and induced fear. Pre-existing structural deficiencies were identified as increasing the risk of illness and death. Knowledge of public health messages coincided with some improvements in water treatment and handwashing, but not changes in open defecation in their community, and was sometimes associated with self-blame or shame. Most participants cited constrained resources, and a minority listed individual neglect, for inconsistent or unimproved practices. Conclusion The experience of epidemic cholera in a rural Haitian community at the beginning of a major outbreak included a high burden and was exacerbated by poverty, which increased risk while hindering practice of known prevention messages. To interrupt cholera transmission, public health education must be paired with investments in structural improvements that expand access to prevention and healthcare services.
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Affiliation(s)
- Yodeline Guillaume
- Center for Global Health, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | | | | | - Louise C Ivers
- Center for Global Health, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts, USA
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11
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Phelps MD, Simonsen L, Jensen PKM. Individual and household exposures associated with cholera transmission in case–control studies: a systematic review. Trop Med Int Health 2019; 24:1151-1168. [DOI: 10.1111/tmi.13293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Matthew D. Phelps
- Copenhagen Center for Disaster Research, Department of Public Health, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Lone Simonsen
- Department of Science and Environment Roskilde University Roskilde Denmark
| | - Peter K. M. Jensen
- Copenhagen Center for Disaster Research, Department of Public Health, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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12
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Wolfe M, Kaur M, Yates T, Woodin M, Lantagne D. A Systematic Review and Meta-Analysis of the Association between Water, Sanitation, and Hygiene Exposures and Cholera in Case-Control Studies. Am J Trop Med Hyg 2018; 99:534-545. [PMID: 29968551 PMCID: PMC6090371 DOI: 10.4269/ajtmh.17-0897] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Case-control studies are conducted to identify cholera transmission routes. Water, sanitation, and hygiene (WASH) exposures can facilitate cholera transmission (risk factors) or interrupt transmission (protective factors). To our knowledge, the association between WASH exposures and cholera from case-control studies has not been systematically analyzed. A systematic review was completed to close this gap, including describing the theory of risk and protection, developing inclusion criteria, searching and selecting studies, assessing quality of evidence, and summarizing associations between cholera and seven predicted WASH protective factors and eight predicted WASH risk factors using meta-analysis and sensitivity analysis. Overall, 47 articles describing 51 individual studies from 30 countries met the inclusion criteria. All eight predicted risk factors were associated with higher odds of cholera (odds ratio [OR] = 1.9-5.6), with heterogeneity (I2) of 0-92%. Of the predicted protective factors, five of seven were associated with lower odds of cholera (OR = 0.35-1.4), with heterogeneity of 57-91%; exceptions were insignificant associations for improved water source (OR = 1.1, heterogeneity 91%) and improved sanitation (OR = 1.4, heterogeneity 68%). Results were robust; 3/70 (5%) associations changed directionality or significance in sensitivity analysis. Meta-analysis results highlight that predicted risk factors are associated with cholera; however, predicted protective factors are not as consistently protective. This variable protection is attributed to 1) cholera transmission via multiple routes and 2) WASH intervention implementation quality variation. Water, sanitation, and hygiene interventions should address multiple transmission routes and be well implemented, according to international guidance, to ensure that field effectiveness matches theoretical efficacy. In addition, future case-control studies should detail WASH characteristics to contextualize results.
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Affiliation(s)
- Marlene Wolfe
- Tufts University Civil and Environmental Engineering Department, Medford, Massachusetts
| | - Mehar Kaur
- Tufts University Civil and Environmental Engineering Department, Medford, Massachusetts
| | - Travis Yates
- Tufts University Civil and Environmental Engineering Department, Medford, Massachusetts
| | - Mark Woodin
- Tufts University Civil and Environmental Engineering Department, Medford, Massachusetts
| | - Daniele Lantagne
- Tufts University Civil and Environmental Engineering Department, Medford, Massachusetts
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13
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Abstract
During emerging disease outbreaks, public health, emergency management officials and decision-makers increasingly rely on epidemiological models to forecast outbreak progression and determine the best response to health crisis needs. Outbreak response strategies derived from such modelling may include pharmaceutical distribution, immunisation campaigns, social distancing, prophylactic pharmaceuticals, medical care, bed surge, security and other requirements. Infectious disease modelling estimates are unavoidably subject to multiple interpretations, and full understanding of a model's limitations may be lost when provided from the disease modeller to public health practitioner to government policymaker. We review epidemiological models created for diseases which are of greatest concern for public health protection. Such diseases, whether transmitted from person-to-person (Ebola, influenza, smallpox), via direct exposure (anthrax), or food and waterborne exposure (cholera, typhoid) may cause severe illness and death in a large population. We examine disease-specific models to determine best practices characterising infectious disease outbreaks and facilitating emergency response and implementation of public health policy and disease control measures.
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Robb K, Null C, Teunis P, Yakubu H, Armah G, Moe CL. Assessment of Fecal Exposure Pathways in Low-Income Urban Neighborhoods in Accra, Ghana: Rationale, Design, Methods, and Key Findings of the SaniPath Study. Am J Trop Med Hyg 2017; 97:1020-1032. [PMID: 28722599 PMCID: PMC5637580 DOI: 10.4269/ajtmh.16-0508] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 04/03/2017] [Indexed: 11/17/2022] Open
Abstract
Rapid urbanization has contributed to an urban sanitation crisis in low-income countries. Residents in low-income, urban neighborhoods often have poor sanitation infrastructure and services and may experience frequent exposure to fecal contamination through a range of pathways. There are little data to prioritize strategies to decrease exposure to fecal contamination in these complex and highly contaminated environments, and public health priorities are rarely considered when planning urban sanitation investments. The SaniPath Study addresses this need by characterizing pathways of exposure to fecal contamination. Over a 16 month period, an in-depth, interdisciplinary exposure assessment was conducted in both public and private domains of four neighborhoods in Accra, Ghana. Microbiological analyses of environmental samples and behavioral data collection techniques were used to quantify fecal contamination in the environment and characterize the behaviors of adults and children associated with exposure to fecal contamination. Environmental samples (n = 1,855) were collected and analyzed for fecal indicators and enteric pathogens. A household survey with 800 respondents and over 500 hours of structured observation of young children were conducted. Approximately 25% of environmental samples were collected in conjunction with structured observations (n = 441 samples). The results of the study highlight widespread and often high levels of fecal contamination in both public and private domains and the food supply. The dominant fecal exposure pathway for young children in the household was through consumption of uncooked produce. The SaniPath Study provides critical information on exposure to fecal contamination in low-income, urban environments and ultimately can inform investments and policies to reduce these public health risks.
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Affiliation(s)
- Katharine Robb
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Clair Null
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
- Mathematica Policy Research, Washington, District of Columbia
| | - Peter Teunis
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
- Centre for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control, RIVM, Amsterdam, The Netherlands
| | - Habib Yakubu
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - George Armah
- The Noguchi Memorial Institute for Medical Research of the University of Ghana, Accra, Ghana
| | - Christine L. Moe
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
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15
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Nishiura H, Tsuzuki S, Yuan B, Yamaguchi T, Asai Y. Transmission dynamics of cholera in Yemen, 2017: a real time forecasting. Theor Biol Med Model 2017; 14:14. [PMID: 28747188 PMCID: PMC5527441 DOI: 10.1186/s12976-017-0061-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/20/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A large epidemic of cholera, caused by Vibrio cholerae, serotype Ogawa, has been ongoing in Yemen, 2017. To improve the situation awareness, the present study aimed to forecast the cholera epidemic, explicitly addressing the reporting delay and ascertainment bias. METHODS Using weekly incidence of suspected cases, updated as a revised epidemic curve every week, the reporting delay was explicitly incorporated into the estimation model. Using the weekly case fatality risk as calculated by the World Health Organization, ascertainment bias was adjusted, enabling us to parameterize the family of logistic curves (i.e., logistic and generalized logistic models) for describing the unbiased incidence in 2017. RESULTS The cumulative incidence at the end of the epidemic, was estimated at 790,778 (95% CI: 700,495, 914,442) cases and 767,029 (95% CI: 690,877, 871,671) cases, respectively, by using logistic and generalized logistic models. It was also estimated that we have just passed through the epidemic peak by week 26, 2017. From week 27 onwards, the weekly incidence was predicted to decrease. CONCLUSIONS Cholera epidemic in Yemen, 2017 was predicted to soon start to decrease. If the weekly incidence is reported in the up-to-the-minute manner and updated in later weeks, not a single data point but the entire epidemic curve must be precisely updated.
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Affiliation(s)
- Hiroshi Nishiura
- Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo, 060-8638, Japan. .,CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama, 332-0012, Japan.
| | - Shinya Tsuzuki
- Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo, 060-8638, Japan.,CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama, 332-0012, Japan
| | - Baoyin Yuan
- Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo, 060-8638, Japan.,CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama, 332-0012, Japan
| | - Takayuki Yamaguchi
- Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo, 060-8638, Japan.,CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama, 332-0012, Japan
| | - Yusuke Asai
- Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo, 060-8638, Japan.,CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama, 332-0012, Japan
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16
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Kirpich A, Weppelmann TA, Yang Y, Morris JG, Longini IM. Controlling cholera in the Ouest Department of Haiti using oral vaccines. PLoS Negl Trop Dis 2017; 11:e0005482. [PMID: 28410382 PMCID: PMC5406029 DOI: 10.1371/journal.pntd.0005482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/26/2017] [Accepted: 03/11/2017] [Indexed: 12/17/2022] Open
Abstract
Following the 2010 cholera outbreak in Haiti, a plan was initiated to provide massive improvements to the sanitation and drinking water infrastructure in order to eliminate cholera from the island of Hispaniola by 2023. Six years and a half billion dollars later, there is little evidence that any substantial improvements have been implemented; with increasing evidence that cholera has become endemic. Thus, it is time to explore strategies to control cholera in Haiti using oral cholera vaccines (OCVs). The potential effects of mass administration of OCVs on cholera transmission were assessed using dynamic compartment models fit to cholera incidence data from the Ouest Department of Haiti. The results indicated that interventions using an OCV that was 60% effective could have eliminated cholera transmission by August 2012 if started five weeks after the initial outbreak. A range of analyses on the ability of OCV interventions started January 1, 2017 to eliminate cholera transmission by 2023 were performed by considering different combinations of vaccine efficacies, vaccine administration rates, and durations of protective immunity. With an average of 50 weeks for the waiting time to vaccination and an average duration of three years for the vaccine-induced immunity, all campaigns that used an OCV with a vaccine efficacy of at least 60% successfully eliminated cholera transmission by 2023. The results of this study suggest that even with a relatively wide range of vaccine efficacies, administration rates, and durations of protective immunity, future epidemics could be controlled at a relatively low cost using mass administration of OCVs in Haiti.
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Affiliation(s)
- Alexander Kirpich
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Thomas A. Weppelmann
- Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - Yang Yang
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Department of Biostatistics, College of Public Health and Health Professions and College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - John Glenn Morris
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Department of Medicine, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Ira M. Longini
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Department of Biostatistics, College of Public Health and Health Professions and College of Medicine, University of Florida, Gainesville, Florida, United States of America
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17
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Affiliation(s)
- Louise C Ivers
- From the Division of Global Health Equity, Brigham and Women's Hospital, Boston; and the Special Consulting Group to the Minister of Health and Population of Haiti, Port-au-Prince. The other members of the Special Consulting Group were Dr. Daphnee Delsoin Benoit, the Honorable Minister of Health and Population, Port-au-Prince, Haiti; Dr. Dennis Chao, Institute for Disease Modeling, Bellevue, WA; Dr. Donald Francois, Ministry of Health and Population, Port-au-Prince, Haiti; Dr. Jeannot Francois, Director of Expanded Program on Immunization, Ministry of Health and Population, Port-au-Prince, Haiti; Dr. Roger Glass, Fogarty International Center, National Institutes of Health (NIH), Bethesda, MD; Dr. Robert Hall, National Institute of Allergy and Infectious Diseases, NIH; Dr. Jerome H. Kim, International Vaccine Institute, Seoul, South Korea; Dr. Bernard Liautaud, Ministry of Health, Port-au-Prince, Haiti; Prof. Ira Longini, University of Florida, Gainesville; Ms. Helen Matzger, Bill and Melinda Gates Foundation, Seattle; Dr. Vittal Mogasale, International Vaccine Institute, Seoul, South Korea; Prof. Glenn Morris, University of Florida, Gainesville; Prof. Jean W. Pape, Weill Cornell Medical College, New York; Prof. David Sack, Johns Hopkins University, Baltimore; and Dr. Jordan Tappero, Centers for Disease Control and Prevention, Atlanta
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18
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Kim JH, Mogasale V, Burgess C, Wierzba TF. Impact of oral cholera vaccines in cholera-endemic countries: A mathematical modeling study. Vaccine 2016; 34:2113-20. [DOI: 10.1016/j.vaccine.2016.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/11/2016] [Accepted: 03/03/2016] [Indexed: 10/22/2022]
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19
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Optimized oral cholera vaccine distribution strategies to minimize disease incidence: A mixed integer programming model and analysis of a Bangladesh scenario. Vaccine 2015; 33:6218-23. [DOI: 10.1016/j.vaccine.2015.09.088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/18/2015] [Accepted: 09/28/2015] [Indexed: 11/24/2022]
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20
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Bakach I, Just MR, Gambhir M, Fung ICH. Typhoid transmission: a historical perspective on mathematical model development. Trans R Soc Trop Med Hyg 2015; 109:679-89. [PMID: 26396161 DOI: 10.1093/trstmh/trv075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/13/2015] [Indexed: 11/13/2022] Open
Abstract
Mathematical models of typhoid transmission were first developed nearly half a century ago. To facilitate a better understanding of the historical development of this field, we reviewed mathematical models of typhoid and summarized their structures and limitations. Eleven models, published in 1971 to 2014, were reviewed. While models of typhoid vaccination are well developed, we highlight the need to better incorporate water, sanitation and hygiene interventions into models of typhoid and other foodborne and waterborne diseases. Mathematical modeling is a powerful tool to test and compare different intervention strategies which is important in the world of limited resources. By working collaboratively, epidemiologists and mathematicians should build better mathematical models of typhoid transmission, including pharmaceutical and non-pharmaceutical interventions, which will be useful in epidemiological and public health practice.
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Affiliation(s)
- Iurii Bakach
- Department of Mathematical Sciences, College of Science and Mathematics, Georgia Southern University, Statesboro, Georgia, USA
| | - Matthew R Just
- Department of Mathematical Sciences, College of Science and Mathematics, Georgia Southern University, Statesboro, Georgia, USA
| | - Manoj Gambhir
- Epidemiological Modelling Unit, Department of Epidemiology and Preventive Medicine, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Isaac Chun-Hai Fung
- Department of Epidemiology, Jiann-Ping Hsu College of Public Health, Georgia Southern University, P.O. Box 8015, Statesboro 30460-8015, Georgia, USA
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Minimizing the Risk of Disease Transmission in Emergency Settings: Novel In Situ Physico-Chemical Disinfection of Pathogen-Laden Hospital Wastewaters. PLoS Negl Trop Dis 2015; 9:e0003776. [PMID: 26110821 PMCID: PMC4482504 DOI: 10.1371/journal.pntd.0003776] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 04/21/2015] [Indexed: 01/05/2023] Open
Abstract
The operation of a health care facility, such as a cholera or Ebola treatment center in an emergency setting, results in the production of pathogen-laden wastewaters that may potentially lead to onward transmission of the disease. The research presented here evaluated the design and operation of a novel treatment system, successfully used by Médecins Sans Frontières in Haiti to disinfect CTC wastewaters in situ, eliminating the need for road haulage and disposal of the waste to a poorly-managed hazardous waste facility, thereby providing an effective barrier to disease transmission through a novel but simple sanitary intervention. The physico-chemical protocols eventually successfully treated over 600 m3 of wastewater, achieving coagulation/flocculation and disinfection by exposure to high pH (Protocol A) and low pH (Protocol B) environments, using thermotolerant coliforms as a disinfection efficacy index. In Protocol A, the addition of hydrated lime resulted in wastewater disinfection and coagulation/flocculation of suspended solids. In Protocol B, disinfection was achieved by the addition of hydrochloric acid, followed by pH neutralization and coagulation/flocculation of suspended solids using aluminum sulfate. Removal rates achieved were: COD >99%; suspended solids >90%; turbidity >90% and thermotolerant coliforms >99.9%. The proposed approach is the first known successful attempt to disinfect wastewater in a disease outbreak setting without resorting to the alternative, untested, approach of ‘super chlorination’ which, it has been suggested, may not consistently achieve adequate disinfection. A basic analysis of costs demonstrated a significant saving in reagent costs compared with the less reliable approach of super-chlorination. The proposed approach to in situ sanitation in cholera treatment centers and other disease outbreak settings represents a timely response to a UN call for onsite disinfection of wastewaters generated in such emergencies, and the ‘Coalition for Cholera Prevention and Control’ recently highlighted the research as meriting serious consideration and further study. Further applications of the method to other emergency settings are being actively explored by the authors through discussion with the World Health Organization with regards to the ongoing Ebola outbreak in West Africa, and with the UK-based NGO Oxfam with regards to excreta-borne disease management in the Philippines and Myanmar, as a component of post-disaster incremental improvements to local sanitation chains. When an outbreak of infectious disease occurs in a low-resource setting, the rapid construction of emergency healthcare facilities may significantly reduce mortality. The facilities also result in the generation of large volumes of highly contaminated fecal waste that represents a potential basis for further disease transmission. Infection protection and control strategies at healthcare facilities must therefore include measures to establish and maintain good water supplies, sanitation and hygiene (WASH). Even where the pathogen of concern is not waterborne, health-care providers have a ‘duty-of-care’ to protect workers and neighboring communities from all excreta-borne diseases. In this study, the authors successfully demonstrated, for the first time, the in situ disinfection of wastewaters from cholera treatment centers during the Haiti cholera outbreak, using a low-cost physicochemical method. The approach is currently being adapted by NGOs to help manage human excreta in other emergency settings, including the current Ebola outbreak. Although the Ebola virus is relatively fragile, it may exist in high concentrations in the bodily fluids (including feces) of those with the disease. The approach to in situ disinfection of excreta described here may therefore support infection control in outbreaks of Ebola and other infectious diseases.
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Anh DD, Lopez AL, Tran HTM, Cuong NV, Thiem VD, Ali M, Deen JL, von Seidlein L, Sack DA. Oral cholera vaccine development and use in Vietnam. PLoS Med 2014; 11:e1001712. [PMID: 25180511 PMCID: PMC4151976 DOI: 10.1371/journal.pmed.1001712] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Anna Lena Lopez and colleagues give an overview of the cholera situation in Vietnam and discuss how an oral cholera vaccine was developed and used as a component of a public health strategy against the disease. Please see later in the article for the Editors' Summary
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Affiliation(s)
- Dang Duc Anh
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Anna Lena Lopez
- University of the Philippines Manila-National Institutes of Health, Manila, Philippines
| | | | | | - Vu Dinh Thiem
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Mohammad Ali
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jacqueline L. Deen
- Menzies School of Health Research, Casuarina, Northern Territory, Australia
| | | | - David A. Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
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Shuai Z, van den Driessche P. Modelling and control of cholera on networks with a common water source. JOURNAL OF BIOLOGICAL DYNAMICS 2014; 9 Suppl 1:90-103. [PMID: 25140600 DOI: 10.1080/17513758.2014.944226] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A mathematical model is formulated for the transmission and spread of cholera in a heterogeneous host population that consists of several patches of homogeneous host populations sharing a common water source. The basic reproduction number ℛ0 is derived and shown to determine whether or not cholera dies out. Explicit formulas are derived for target/type reproduction numbers that measure the control strategies required to eradicate cholera from all patches.
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Affiliation(s)
- Zhisheng Shuai
- a Department of Mathematics , University of Central Florida , Orlando , FL 32816 , USA
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24
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Etienne CF, Tappero JW, Marston BJ, Frieden TR, Kenyon TA, Andrus JK. Cholera elimination in Hispaniola. Am J Trop Med Hyg 2013; 89:615-616. [PMID: 24106186 PMCID: PMC3795089 DOI: 10.4269/ajtmh.13-0510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
| | | | | | | | | | - Jon K. Andrus
- * Address correspondence to Jon K. Andrus, Pan American Health Organization, 525 23rd Street, NW, Washington, DC 20037. E-mail:
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