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Türkün C, Gölgeli M, Atay FM. A mathematical interpretation for outbreaks of bacterial meningitis under the effect of time-dependent transmission parameters. NONLINEAR DYNAMICS 2023; 111:1-18. [PMID: 37361004 PMCID: PMC10235855 DOI: 10.1007/s11071-023-08577-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/08/2023] [Indexed: 06/28/2023]
Abstract
We consider a SIR-type compartmental model divided into two age classes to explain the seasonal exacerbations of bacterial meningitis, especially among children outside of the meningitis belt. We describe the seasonal forcing through time-dependent transmission parameters that may represent the outbreak of the meningitis cases after the annual pilgrimage period (Hajj) or uncontrolled inflows of irregular immigrants. We present and analyse a mathematical model with time-dependent transmission. We consider not only periodic functions in the analysis but also general non-periodic transmission processes. We show that the long-time average values of transmission functions can be used as a stability marker of the equilibrium. Furthermore, we interpret the basic reproduction number in case of time-dependent transmission functions. Numerical simulations support and help visualize the theoretical results.
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Affiliation(s)
- Can Türkün
- Department of Mathematics, TOBB University of Economics and Technology, Ankara, Turkey
- Present Address: Department of Industrial Engineering, Altınbaş University, Istanbul, Turkey
| | - Meltem Gölgeli
- Department of Mathematics, TOBB University of Economics and Technology, Ankara, Turkey
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Prunas O, Weinberger DM, Medini D, Tizzoni M, Argante L. Evaluating the Impact of Meningococcal Vaccines With Synthetic Controls. Am J Epidemiol 2022; 191:724-734. [PMID: 34753175 PMCID: PMC8971084 DOI: 10.1093/aje/kwab266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/14/2021] [Accepted: 10/29/2021] [Indexed: 11/19/2022] Open
Abstract
Invasive meningococcal disease (IMD) has a low and unpredictable incidence, presenting challenges for real-world evaluations of meningococcal vaccines. Traditionally, meningococcal vaccine impact is evaluated by predicting counterfactuals from pre-immunization IMD incidences, possibly controlling for IMD in unvaccinated age groups, but the selection of controls can influence results. We retrospectively applied a synthetic control (SC) method, previously used for pneumococcal disease, to data from 2 programs for immunization of infants against serogroups B and C IMD in England and Brazil. Time series of infectious/noninfectious diseases in infants and IMD cases in older unvaccinated age groups were used as candidate controls, automatically combined in a SC through Bayesian variable selection. SC closely predicted IMD in absence of vaccination, adjusting for nontrivial changes in IMD incidence. Vaccine impact estimates were in line with previous assessments. IMD cases in unvaccinated age groups were the most frequent SC-selected controls. Similar results were obtained when excluding IMD from control sets and using other diseases only, particularly respiratory diseases and measles. Using non-IMD controls may be important where there are herd immunity effects. SC is a robust and flexible method that addresses uncertainty introduced when equally plausible controls exhibit different post-immunization behaviors, allowing objective comparisons of IMD programs between countries.
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Affiliation(s)
| | | | - Duccio Medini
- Correspondence to Dr. Duccio Medini, Via Fiorentina 1, Siena, 53100, Italy (e-mail: )
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Toor J, Echeverria-Londono S, Li X, Abbas K, Carter ED, Clapham HE, Clark A, de Villiers MJ, Eilertson K, Ferrari M, Gamkrelidze I, Hallett TB, Hinsley WR, Hogan D, Huber JH, Jackson ML, Jean K, Jit M, Karachaliou A, Klepac P, Kraay A, Lessler J, Li X, Lopman BA, Mengistu T, Metcalf CJE, Moore SM, Nayagam S, Papadopoulos T, Perkins TA, Portnoy A, Razavi H, Razavi-Shearer D, Resch S, Sanderson C, Sweet S, Tam Y, Tanvir H, Tran Minh Q, Trotter CL, Truelove SA, Vynnycky E, Walker N, Winter A, Woodruff K, Ferguson NM, Gaythorpe KAM. Lives saved with vaccination for 10 pathogens across 112 countries in a pre-COVID-19 world. eLife 2021; 10:e67635. [PMID: 34253291 PMCID: PMC8277373 DOI: 10.7554/elife.67635] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/26/2021] [Indexed: 12/12/2022] Open
Abstract
Background Vaccination is one of the most effective public health interventions. We investigate the impact of vaccination activities for Haemophilus influenzae type b, hepatitis B, human papillomavirus, Japanese encephalitis, measles, Neisseria meningitidis serogroup A, rotavirus, rubella, Streptococcus pneumoniae, and yellow fever over the years 2000-2030 across 112 countries. Methods Twenty-one mathematical models estimated disease burden using standardised demographic and immunisation data. Impact was attributed to the year of vaccination through vaccine-activity-stratified impact ratios. Results We estimate 97 (95%CrI[80, 120]) million deaths would be averted due to vaccination activities over 2000-2030, with 50 (95%CrI[41, 62]) million deaths averted by activities between 2000 and 2019. For children under-5 born between 2000 and 2030, we estimate 52 (95%CrI[41, 69]) million more deaths would occur over their lifetimes without vaccination against these diseases. Conclusions This study represents the largest assessment of vaccine impact before COVID-19-related disruptions and provides motivation for sustaining and improving global vaccination coverage in the future. Funding VIMC is jointly funded by Gavi, the Vaccine Alliance, and the Bill and Melinda Gates Foundation (BMGF) (BMGF grant number: OPP1157270 / INV-009125). Funding from Gavi is channelled via VIMC to the Consortium's modelling groups (VIMC-funded institutions represented in this paper: Imperial College London, London School of Hygiene and Tropical Medicine, Oxford University Clinical Research Unit, Public Health England, Johns Hopkins University, The Pennsylvania State University, Center for Disease Analysis Foundation, Kaiser Permanente Washington, University of Cambridge, University of Notre Dame, Harvard University, Conservatoire National des Arts et Métiers, Emory University, National University of Singapore). Funding from BMGF was used for salaries of the Consortium secretariat (authors represented here: TBH, MJ, XL, SE-L, JT, KW, NMF, KAMG); and channelled via VIMC for travel and subsistence costs of all Consortium members (all authors). We also acknowledge funding from the UK Medical Research Council and Department for International Development, which supported aspects of VIMC's work (MRC grant number: MR/R015600/1).JHH acknowledges funding from National Science Foundation Graduate Research Fellowship; Richard and Peggy Notebaert Premier Fellowship from the University of Notre Dame. BAL acknowledges funding from NIH/NIGMS (grant number R01 GM124280) and NIH/NIAID (grant number R01 AI112970). The Lives Saved Tool (LiST) receives funding support from the Bill and Melinda Gates Foundation.This paper was compiled by all coauthors, including two coauthors from Gavi. Other funders had no role in study design, data collection, data analysis, data interpretation, or writing of the report. All authors had full access to all the data in the study and had final responsibility for the decision to submit for publication.
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Affiliation(s)
- Jaspreet Toor
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Susy Echeverria-Londono
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Xiang Li
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Kaja Abbas
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Emily D Carter
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | - Hannah E Clapham
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore; Oxford University Clinical Research Unit, Vietnam; Nuffield Department of Medicine, Oxford UniversityOxfordUnited Kingdom
| | - Andrew Clark
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Margaret J de Villiers
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | | | | | | | - Timothy B Hallett
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Wes R Hinsley
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | | | - John H Huber
- Department of Biological Sciences, University of Notre DameNotre DameUnited States
| | | | - Kevin Jean
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
- Laboratoire MESuRS and Unite PACRI, Institut Pasteur, Conservatoire National des Arts et MetiersParisFrance
| | - Mark Jit
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
- University of Hong Kong, Hong Kong Special Administrative RegionHong KongChina
| | | | - Petra Klepac
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Alicia Kraay
- Rollins School of Public Health, Emory UniversityAtlantaUnited States
| | - Justin Lessler
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | - Xi Li
- IndependentAtlantaUnited States
| | - Benjamin A Lopman
- Rollins School of Public Health, Emory UniversityAtlantaUnited States
| | | | | | - Sean M Moore
- Department of Biological Sciences, University of Notre DameNotre DameUnited States
| | - Shevanthi Nayagam
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Imperial College LondonLondonUnited Kingdom
| | - Timos Papadopoulos
- Public Health EnglandLondonUnited Kingdom
- University of SouthamptonSouthamptonUnited Kingdom
| | - T Alex Perkins
- Department of Biological Sciences, University of Notre DameNotre DameUnited States
| | - Allison Portnoy
- Center for Health Decision Science, Harvard T H Chan School of Public Health, Harvard UniversityCambridgeUnited States
| | - Homie Razavi
- Center for Disease Analysis FoundationLafayetteUnited States
| | | | - Stephen Resch
- Center for Health Decision Science, Harvard T H Chan School of Public Health, Harvard UniversityCambridgeUnited States
| | - Colin Sanderson
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Steven Sweet
- Center for Health Decision Science, Harvard T H Chan School of Public Health, Harvard UniversityCambridgeUnited States
| | - Yvonne Tam
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | - Hira Tanvir
- London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Quan Tran Minh
- Department of Biological Sciences, University of Notre DameNotre DameUnited States
| | | | - Shaun A Truelove
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | | | - Neff Walker
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | - Amy Winter
- Bloomberg School of Public Health, Johns Hopkins UniversityBaltimoreUnited States
| | - Kim Woodruff
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Neil M Ferguson
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Katy AM Gaythorpe
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
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Gaythorpe KAM, Abbas K, Huber J, Karachaliou A, Thakkar N, Woodruff K, Li X, Echeverria-Londono S, Ferrari M, Jackson ML, McCarthy K, Perkins TA, Trotter C, Jit M. Impact of COVID-19-related disruptions to measles, meningococcal A, and yellow fever vaccination in 10 countries. eLife 2021; 10:e67023. [PMID: 34165077 PMCID: PMC8263060 DOI: 10.7554/elife.67023] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 06/23/2021] [Indexed: 12/30/2022] Open
Abstract
Background Childhood immunisation services have been disrupted by the COVID-19 pandemic. WHO recommends considering outbreak risk using epidemiological criteria when deciding whether to conduct preventive vaccination campaigns during the pandemic. Methods We used two to three models per infection to estimate the health impact of 50% reduced routine vaccination coverage in 2020 and delay of campaign vaccination from 2020 to 2021 for measles vaccination in Bangladesh, Chad, Ethiopia, Kenya, Nigeria, and South Sudan, for meningococcal A vaccination in Burkina Faso, Chad, Niger, and Nigeria, and for yellow fever vaccination in the Democratic Republic of Congo, Ghana, and Nigeria. Our counterfactual comparative scenario was sustaining immunisation services at coverage projections made prior to COVID-19 (i.e. without any disruption). Results Reduced routine vaccination coverage in 2020 without catch-up vaccination may lead to an increase in measles and yellow fever disease burden in the modelled countries. Delaying planned campaigns in Ethiopia and Nigeria by a year may significantly increase the risk of measles outbreaks (both countries did complete their supplementary immunisation activities (SIAs) planned for 2020). For yellow fever vaccination, delay in campaigns leads to a potential disease burden rise of >1 death per 100,000 people per year until the campaigns are implemented. For meningococcal A vaccination, short-term disruptions in 2020 are unlikely to have a significant impact due to the persistence of direct and indirect benefits from past introductory campaigns of the 1- to 29-year-old population, bolstered by inclusion of the vaccine into the routine immunisation schedule accompanied by further catch-up campaigns. Conclusions The impact of COVID-19-related disruption to vaccination programs varies between infections and countries. Planning and implementation of campaigns should consider country and infection-specific epidemiological factors and local immunity gaps worsened by the COVID-19 pandemic when prioritising vaccines and strategies for catch-up vaccination. Funding Bill and Melinda Gates Foundation and Gavi, the Vaccine Alliance.
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Affiliation(s)
- Katy AM Gaythorpe
- MRC Centre for Global Infectious Disease Analysis, Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Kaja Abbas
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
| | - John Huber
- Department of Biological Sciences, University of Notre DameSouth BendUnited States
| | | | - Niket Thakkar
- Institute for Disease Modeling, Bill & Melinda Gates FoundationSeattleUnited States
| | - Kim Woodruff
- MRC Centre for Global Infectious Disease Analysis, Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Xiang Li
- MRC Centre for Global Infectious Disease Analysis, Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | - Susy Echeverria-Londono
- MRC Centre for Global Infectious Disease Analysis, Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College LondonLondonUnited Kingdom
| | | | | | - Kevin McCarthy
- Institute for Disease Modeling, Bill & Melinda Gates FoundationSeattleUnited States
| | - T Alex Perkins
- Department of Biological Sciences, University of Notre DameSouth BendUnited States
| | - Caroline Trotter
- Department of Veterinary Medicine, University of CambridgeCambridgeUnited Kingdom
| | - Mark Jit
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
- School of Public Health, University of Hong KongHong Kong SARChina
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Mazamay S, Broutin H, Bompangue D, Muyembe JJ, Guégan JF. The environmental drivers of bacterial meningitis epidemics in the Democratic Republic of Congo, central Africa. PLoS Negl Trop Dis 2020; 14:e0008634. [PMID: 33027266 PMCID: PMC7540884 DOI: 10.1371/journal.pntd.0008634] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 07/23/2020] [Indexed: 01/17/2023] Open
Abstract
INTRODUCTION Bacterial meningitis still constitutes an important threat in Africa. In the meningitis belt, a clear seasonal pattern in the incidence of meningococcal disease during the dry season has been previously correlated with several environmental parameters like dust and sand particles as well as the Harmattan winds. In parallel, the evidence of seasonality in meningitis dynamics and its environmental variables remain poorly studied outside the meningitis belt. This study explores several environmental factors associated with meningitis cases in the Democratic Republic of Congo (DRC), central Africa, outside the meningitis belt area. METHODS Non-parametric Kruskal-Wallis' tests were used to establish the difference between the different health zones, climate and vegetation types in relation to both the number of cases and attack rates for the period 2000-2018. The relationships between the number of meningitis cases for the different health zones and environmental and socio-economical parameters collected were modeled using different generalized linear (GLMs) and generalized linear mixed models (GLMMs), and different error structure in the different models, i.e., Poisson, binomial negative, zero-inflated binomial negative and more elaborated multi-hierarchical zero-inflated binomial negative models, with randomization of certain parameters or factors (health zones, vegetation and climate types). Comparing the different statistical models, the model with the smallest Akaike's information criterion (AIC) were selected as the best ones. 515 different health zones from 26 distinct provinces were considered for the construction of the different GLM and GLMM models. RESULTS Non-parametric bivariate statistics showed that there were more meningitis cases in urban health zones than in rural conditions (χ2 = 6.910, p-value = 0.009), in areas dominated by savannah landscape than in areas with dense forest or forest in mountainous areas (χ2 = 15.185, p-value = 0.001), and with no significant difference between climate types (χ2 = 1.211, p-value = 0,449). Additionally, no significant difference was observed for attack rate between the two types of heath zones (χ2 = 0.982, p-value = 0.322). Conversely, strong differences in attack rate values were obtained for vegetation types (χ2 = 13.627, p-value = 0,001) and climate types (χ2 = 13.627, p-value = 0,001). This work demonstrates that, all other parameters kept constant, an urban health zone located at high latitude and longitude eastwards, located at low-altitude like in valley ecosystems predominantly covered by savannah biome, with a humid tropical climate are at higher risk for the development of meningitis. In addition, the regions with mean range temperature and a population with a low index of economic well-being (IEW) constitute the perfect conditions for the development of meningitis in DRC. CONCLUSION In a context of global environmental change, particularly climate change, our findings tend to show that an interplay of different environmental and socio-economic drivers are important to consider in the epidemiology of bacterial meningitis epidemics in DRC. This information is important to help improving meningitis control strategies in a large country located outside of the so-called meningitis belt.
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Affiliation(s)
- Serge Mazamay
- Département de Microbiologie, Faculté de Médecine, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
- MIVEGEC, IRD, CNRS, Université de Montpellier, Montpellier, France
| | - Hélène Broutin
- MIVEGEC, IRD, CNRS, Université de Montpellier, Montpellier, France
- Département de Parasitologie-Mycologie, Faculté de Médecine, Université Cheikh Anta Diop (UCAD), Dakar, Sénégal
- Centre de Recherche en Evolution et Ecologie de la Santé (CREES), Montpellier, France
| | - Didier Bompangue
- Département de Microbiologie, Faculté de Médecine, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
- Chrono-Environnement, UMR CNRS 6249 Université de Franche-Comté, Besançon, France
| | - Jean-Jacques Muyembe
- Département de Microbiologie, Faculté de Médecine, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Jean-François Guégan
- MIVEGEC, IRD, CNRS, Université de Montpellier, Montpellier, France
- ASTRE, INRAE, Cirad, Université de Montpellier, Campus International de Baillarguet, Montpellier, France
- oneHEALTH Global Research Programme, FutureEarth programme, Paris, France
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Abstract
Meningococcal carriage dynamics drive patterns of invasive disease. The distribution of carriage by age has been well described in Europe, but not in the African meningitis belt, a region characterised by frequent epidemics of meningitis. We aimed to estimate the age-specific prevalence of meningococcal carriage by season in the African meningitis belt. We searched PubMed, Web of Science, the Cochrane Library and grey literature for papers reporting carriage of Neisseria meningitidis in defined age groups in the African meningitis belt. We used a mixed-effects logistic regression to model meningococcal carriage prevalence as a function of age, adjusting for season, location and year. Carriage prevalence increased from low prevalence in infants (0.595% in the rainy season, 95% CI 0.482–0.852%) to a broad peak at age 10 (1.94%, 95% CI 1.87–2.47%), then decreased in adolescence. The odds of carriage were significantly increased during the dry season (OR 1.5 95% CI 1.4–1.7) and during outbreaks (OR 6.7 95% CI 1.6–29). Meningococcal carriage in the African meningitis belt peaks at a younger age compared to Europe. This is consistent with contact studies in Africa, which show that children 10–14 years have the highest frequency of contacts. Targeting older children in Africa for conjugate vaccination may be effective in reducing meningococcal transmission.
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Musa SS, Zhao S, Hussaini N, Habib AG, He D. Mathematical modeling and analysis of meningococcal meningitis transmission dynamics. INT J BIOMATH 2020. [DOI: 10.1142/s1793524520500060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Meningococcal meningitis (MCM) is one of the serious public health threats in the tropical and sub-tropical regions. In this paper, we propose an epidemic model to study the transmission dynamics of MCM with high- and low-risk susceptible populations. The model considers two different groups of susceptible individuals depending on the availability of medical resources (MR, including hospitals, health workers, etc.), which varies the infection risk. We find that the model exhibits the phenomenon of backward bifurcation (BB), which increases the difficulty of MCM control since the dynamics are not merely relying on the basic reproduction number, [Formula: see text]. This study explores the effects of MR on the MCM epidemics by mathematical analysis and shows the existence of BB on MCM disease. Our findings suggest that providing adequate MR in a community is crucial in mitigating MCM incidences and deaths, especially, in the MCM endemic regions.
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Affiliation(s)
- Salihu Sabiu Musa
- Department of Applied Mathematics, Hong Kong Polytechnic University, Hung Hom Hong Kong, P. R. China
- Department of Mathematics, Kano University of Science and Technology, Wudil, Nigeria
| | - Shi Zhao
- Department of Applied Mathematics, Hong Kong Polytechnic University, Hung Hom Hong Kong, P. R. China
- School of Nursing, Hong Kong Polytechnic University, Hung Hom, Hong Kong, P. R. China
- Division of Biostatistics, JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, P. R. China
| | - Nafiu Hussaini
- Department of Mathematical Sciences, Bayero University, Kano, Nigeria
| | | | - Daihai He
- Department of Applied Mathematics, Hong Kong Polytechnic University, Hung Hom Hong Kong, P. R. China
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Abdullahi Baba I, Ibrahim Olamilekan L, Yusuf A, Baleanu D. Analysis of meningitis model: A case study of northern Nigeria. AIMS BIOENGINEERING 2020. [DOI: 10.3934/bioeng.2020016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Tilahun GT. Optimal Control Analysis of Pneumonia and Meningitis Coinfection. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:2658971. [PMID: 31662785 PMCID: PMC6778889 DOI: 10.1155/2019/2658971] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/26/2019] [Accepted: 08/20/2019] [Indexed: 11/23/2022]
Abstract
In this paper, we proposed a deterministic model of pneumonia-meningitis coinfection. We used a system of seven ordinary differential equations. Firstly, the qualitative behaviours of the model such as positivity of the solution, existence of the solution, the equilibrium points, basic reproduction number, analysis of equilibrium points, and sensitivity analysis are studied. The disease-free equilibrium is locally asymptotically stable if the basic reproduction number is kept less than unity, and conditions for global stability are established. Then, the basic model is extended to optimal control by incorporating four control interventions, such as prevention of pneumonia as well as meningitis and also treatment of pneumonia and meningitis diseases. The optimality system is obtained by using Pontryagin's maximum principle. For simulation of the optimality system, we proposed five strategies to check the effect of the controls. First, we consider prevention only for both diseases, and the result shows that applying prevention control has a great impact in bringing down the expansion of pneumonia, meningitis, and their coinfection in the specified period of time. The other strategies are prevention effort for pneumonia and treatment effort for meningitis, prevention effort for meningitis and treatment effort for pneumonia, treatment effort for both diseases, and using all interventions. We obtained that each of the listed strategies is effective in minimizing the expansion of pneumonia-only, meningitis-only, and coinfectious population in the specified period of time.
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Arifin SMN, Zimmer C, Trotter C, Colombini A, Sidikou F, LaForce FM, Cohen T, Yaesoubi R. Cost-Effectiveness of Alternative Uses of Polyvalent Meningococcal Vaccines in Niger: An Agent-Based Transmission Modeling Study. Med Decis Making 2019; 39:553-567. [PMID: 31268405 PMCID: PMC6786941 DOI: 10.1177/0272989x19859899] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Background. Despite the introduction of an effective serogroup A conjugate vaccine (MenAfriVac™), sporadic epidemics of other Neisseria meningitidis serogroups remain a concern in Africa. Polyvalent meningococcal conjugate (PMC) vaccines may offer alternatives to current strategies that rely on routine infant vaccination with MenAfriVac plus, in the event of an epidemic, district-specific reactive campaigns using polyvalent meningococcal polysaccharide (PMP) vaccines. Methods. We developed an agent-based transmission model of N. meningitidis in Niger to compare the health effects and costs of current vaccination practice and 3 alternatives. Each alternative replaces MenAfriVac in the infant vaccination series with PMC and either replaces PMP with PMC for reactive campaigns or implements a one-time catch up campaign with PMC for children and young adults. Results. Over a 28-year period, replacement of MenAfriVac with PMC in the infant immunization series and of PMP in reactive campaigns would avert 63% of expected cases (95% prediction interval 49%-75%) if elimination of serogroup A is not followed by serogroup replacement. At a PMC price of $4/dose, this would cost $1412 ($81-$3510) per disability-adjusted life-year (DALY) averted. If serogroup replacement occurs, the cost-effectiveness of this strategy improves to $662 (cost-saving, $2473) per DALY averted. Sensitivity analyses accounting for incomplete laboratory confirmation suggest that a catch-up PMC campaign would also meet standard cost-effectiveness thresholds. Limitations. The assumption that polyvalent vaccines offer similar protection against all serogroups is simplifying. Conclusions. The use of PMC vaccines to replace MenAfriVac in routine infant immunization and in district-specific reactive campaigns would have important health benefits and is likely to be cost-effective in Niger. An additional PMC catch-up campaign would also be cost-effective if we account for incomplete laboratory reporting.
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Affiliation(s)
- S M Niaz Arifin
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Christoph Zimmer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Caroline Trotter
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | | | - Fati Sidikou
- Centre de Recherche Medicale et Sanitaire (CERMES), Niamey, NE, Niger
| | | | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Reza Yaesoubi
- Department of Health Policy and Management, Yale School of Public Health, New Haven, CT, USA
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Agusto F, Leite M. Optimal control and cost-effective analysis of the 2017 meningitis outbreak in Nigeria. Infect Dis Model 2019; 4:161-187. [PMID: 31193915 PMCID: PMC6545339 DOI: 10.1016/j.idm.2019.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 11/17/2022] Open
Abstract
This paper presents a deterministic model for Neisseria meningitidis, a bacterium that causes meningitis. The model was parameterized using data from the 2017 meningitis outbreak in Nigeria. Optimal control theory was applied to investigate the optimal strategy for curtailing the spread of the disease using control variables determined from sensitivity analysis. These control variables are personal-protection such as the use of facial masks, and vaccination. The results show that the two controls avert more infections at low costs. Furthermore, a reciprocal relationship exists between the use of facial masks and vaccine. That is, when the use of facial masks is high, the use of vaccine is low and vice versa. Cost-effective analysis was applied to investigate the most cost-effective strategy from various combination of control strategies. The results show that strategy combining all the control variables is the most cost-effective strategy followed by the strategy involving both personal-protection, the vaccination-only strategy was the least cost-effective. Although vaccination strategy is not cost-effective in this study, it is as effective in curtailing the infection as the other two control strategies. The study suggests that governments of communities with limited resources should consider complementing the use of vaccine with the use of facial mask particularly in hard-to-reach places in their communities.
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Affiliation(s)
- F.B. Agusto
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, United States
| | - M.C.A. Leite
- Mathematics and Statistics Unit, University of South Florida at St. Petersburg, FL, United States
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12
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Cooper LV, Robson A, Trotter CL, Aseffa A, Collard JM, Daugla DM, Diallo A, Hodgson A, Jusot JF, Omotara B, Sow S, Hassan-King M, Manigart O, Nascimento M, Woukeu A, Chandramohan D, Borrow R, Maiden MCJ, Greenwood B, Stuart JM. Risk factors for acquisition of meningococcal carriage in the African meningitis belt. Trop Med Int Health 2019; 24:392-400. [PMID: 30729627 PMCID: PMC6563094 DOI: 10.1111/tmi.13203] [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] [Indexed: 01/05/2023]
Abstract
OBJECTIVE To investigate potential risk factors for acquisition in seven countries of the meningitis belt. METHODS Households were followed up every 2 weeks for 2 months, then monthly for a further 4 months. Pharyngeal swabs were collected from all available household members at each visit and questionnaires completed. Risks of acquisition over the whole study period and for each visit were analysed by a series of logistic regressions. RESULTS Over the course of the study, acquisition was higher in: (i) 5-to 14-year olds, as compared with those 30 years or older (OR 3.6, 95% CI 1.4-9.9); (ii) smokers (OR 3.6, 95% CI 0.98-13); and (iii) those exposed to wood smoke at home (OR 2.6 95% CI 1.3-5.6). The risk of acquisition from one visit to the next was higher in those reporting a sore throat during the dry season (OR 3.7, 95% CI 2.0-6.7) and lower in those reporting antibiotic use (OR 0.17, 95% CI 0.03-0.56). CONCLUSIONS Acquisition of meningococcal carriage peaked in school age children. Recent symptoms of sore throat during the dry season, but not during the rainy season, were associated with a higher risk of acquisition. Upper respiratory tract infections may be an important driver of epidemics in the meningitis belt.
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Affiliation(s)
| | | | | | - Abraham Aseffa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Jean-Marc Collard
- Centre de Recherche Médicale et Sanitaire, Niamey, Niger.,Bactériologie expérimentale, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | | | | | | | | | - Babatunji Omotara
- Department of Community Medicine, University of Maiduguri, Maiduguri, Nigeria
| | - Samba Sow
- Centre pour les Vaccins en Développement, Bamako, Mali
| | - Musa Hassan-King
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Olivier Manigart
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Maria Nascimento
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Arouna Woukeu
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Daniel Chandramohan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Ray Borrow
- Public Health England Vaccine Evaluation Unit, Manchester, UK
| | | | - Brian Greenwood
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - James M Stuart
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
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13
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Greenwood BM, Aseffa A, Caugant DA, Diallo K, Kristiansen PA, Maiden MCJ, Stuart JM, Trotter CL. Narrative review of methods and findings of recent studies on the carriage of meningococci and other Neisseria species in the African Meningitis Belt. Trop Med Int Health 2019; 24:143-154. [PMID: 30461138 PMCID: PMC7380001 DOI: 10.1111/tmi.13185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To review the findings of studies of pharyngeal carriage of Neisseria meningitidis and related species conducted in the African meningitis belt since a previous review published in 2007. METHODS PubMed and Web of Science were searched in July 2018 using the terms 'meningococcal OR Neisseria meningitidis OR lactamica AND carriage AND Africa', with the search limited to papers published on or after 1st January 2007. We conducted a narrative review of these publications. RESULTS One hundred and thirteen papers were identified using the search terms described above, 20 of which reported new data from surveys conducted in an African meningitis belt country. These papers described 40 surveys conducted before the introduction of the group A meningococcal conjugate vaccine (MenAfriVacR ) during which 66 707 pharyngeal swabs were obtained. Carriage prevalence of N. meningitidis varied substantially by time and place, ranging from <1% to 24%. The mean pharyngeal carriage prevalence of N. meningitidis across all surveys was 4.5% [95% CI: 3.4%, 6.8%] and that of capsulated N. meningitidis was 2.8% [95% CI: 1.9%; 5.2%]. A study of households provided strong evidence for meningococcal transmission within and outside households. The introduction of MenAfriVac® led to marked reductions in carriage of the serogroup A meningococcus in Burkina Faso and Chad. CONCLUSIONS Recent studies employing standardised methods confirm the findings of older studies that carriage of N. meningitidis in the African meningitis belt is highly variable over time and place, but generally occurs with a lower prevalence and shorter duration than reported from industrialised countries.
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Affiliation(s)
| | | | | | - Kanny Diallo
- Department of BacteriologyNoguchi Memorial Research InstituteUniversity of LegonAccraLegon
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14
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Koutangni T, Crépey P, Woringer M, Porgho S, Bicaba BW, Tall H, Mueller JE. Compartmental models for seasonal hyperendemic bacterial meningitis in the African meningitis belt. Epidemiol Infect 2018; 147:e14. [PMID: 30264686 PMCID: PMC6520558 DOI: 10.1017/s0950268818002625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 07/03/2018] [Accepted: 08/22/2018] [Indexed: 11/29/2022] Open
Abstract
The pathophysiological mechanisms underlying the seasonal dynamic and epidemic occurrence of bacterial meningitis in the African meningitis belt remain unknown. Regular seasonality (seasonal hyperendemicity) is observed for both meningococcal and pneumococcal meningitis and understanding this is critical for better prevention and modelling. The two principal hypotheses for hyperendemicity during the dry season imply (1) an increased risk of invasive disease given asymptomatic carriage of meningococci and pneumococci; or (2) an increased transmission of these bacteria from carriers and ill individuals. In this study, we formulated three compartmental deterministic models of seasonal hyperendemicity, featuring one (model1-'inv' or model2-'transm'), or a combination (model3-'inv-transm') of the two hypotheses. We parameterised the models based on current knowledge on meningococcal and pneumococcal biology and pathophysiology. We compared the three models' performance in reproducing weekly incidences of suspected cases of acute bacterial meningitis reported by health centres in Burkina Faso during 2004-2010, through the meningitis surveillance system. The three models performed well (coefficient of determination R2, 0.72, 0.86 and 0.87, respectively). Model2-'transm' and model3-'inv-transm' better captured the amplitude of the seasonal incidence. However, model2-'transm' required a higher constant invasion rate for a similar average baseline transmission rate. The results suggest that a combination of seasonal changes of the risk of invasive disease and carriage transmission is involved in the hyperendemic seasonality of bacterial meningitis in the African meningitis belt. Consequently, both interventions reducing the risk of nasopharyngeal invasion and the bacteria transmission, especially during the dry season are believed to be needed to limit the recurrent seasonality of bacterial meningitis in the meningitis belt.
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Affiliation(s)
- T. Koutangni
- Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France
- Unité de l'Epidémiologie des Maladies Emergentes, Institut Pasteur, 25-28 Rue du Dr Roux, 75015 Paris, France
- EHESP French School of Public Health, Sorbonne Paris Cité, 20 avenue George Sand, 93210 La Plaine St Denis, France
| | - P. Crépey
- UMR Emergence des Pathologies Virales, Université Aix-Marseille – IRD 190 – Inserm 1207 – EHESP, 27 Boulevard Jean-Moulin 13385 Marseille Cedex 5, France
- Univ Rennes, EHESP, REPERES (Recherche en pharmaco-épidémiologie et recours aux soins) – EA 7449, F-35000 Rennes, France
| | - M. Woringer
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), PSL Research University, 45 Rue dʼUlm, 75005 Paris, France
| | - S. Porgho
- Direction de la Lutte contre la Maladie, Ministère de la Santé, 03 BP 7035 Ouagadougou 03, Burkina Faso
| | - B. W. Bicaba
- Direction de la Lutte contre la Maladie, Ministère de la Santé, 03 BP 7035 Ouagadougou 03, Burkina Faso
| | - H. Tall
- Agence de Médecine Préventive, 10 BP 638. Ouagadougou, Burkina Faso
| | - J. E. Mueller
- Unité de l'Epidémiologie des Maladies Emergentes, Institut Pasteur, 25-28 Rue du Dr Roux, 75015 Paris, France
- EHESP French School of Public Health, Sorbonne Paris Cité, 20 avenue George Sand, 93210 La Plaine St Denis, France
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15
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Mathematical Modelling of Bacterial Meningitis Transmission Dynamics with Control Measures. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2018; 2018:2657461. [PMID: 29780431 PMCID: PMC5892307 DOI: 10.1155/2018/2657461] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 01/04/2018] [Indexed: 12/03/2022]
Abstract
Vaccination and treatment are the most effective ways of controlling the transmission of most infectious diseases. While vaccination helps susceptible individuals to build either a long-term immunity or short-term immunity, treatment reduces the number of disease-induced deaths and the number of infectious individuals in a community/nation. In this paper, a nonlinear deterministic model with time-dependent controls has been proposed to describe the dynamics of bacterial meningitis in a population. The model is shown to exhibit a unique globally asymptotically stable disease-free equilibrium ℰ0, when the effective reproduction number ℛVT ≤ 1, and a globally asymptotically stable endemic equilibrium ℰ1, when ℛVT > 1; and it exhibits a transcritical bifurcation at ℛVT = 1. Carriers have been shown (by Tornado plot) to have a higher chance of spreading the infection than those with clinical symptoms who will sometimes be bound to bed during the acute phase of the infection. In order to find the best strategy for minimizing the number of carriers and ill individuals and the cost of control implementation, an optimal control problem is set up by defining a Lagrangian function L to be minimized subject to the proposed model. Numerical simulation of the optimal problem demonstrates that the best strategy to control bacterial meningitis is to combine vaccination with other interventions (such as treatment and public health education). Additionally, this research suggests that stakeholders should press hard for the production of existing/new vaccines and antibiotics and their disbursement to areas that are most affected by bacterial meningitis, especially Sub-Saharan Africa; furthermore, individuals who live in communities where the environment is relatively warm (hot/moisture) are advised to go for vaccination against bacterial meningitis.
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16
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Yaesoubi R, Trotter C, Colijn C, Yaesoubi M, Colombini A, Resch S, Kristiansen PA, LaForce FM, Cohen T. The cost-effectiveness of alternative vaccination strategies for polyvalent meningococcal vaccines in Burkina Faso: A transmission dynamic modeling study. PLoS Med 2018; 15:e1002495. [PMID: 29364884 PMCID: PMC5783340 DOI: 10.1371/journal.pmed.1002495] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 12/19/2017] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The introduction of a conjugate vaccine for serogroup A Neisseria meningitidis has dramatically reduced disease in the African meningitis belt. In this context, important questions remain about the performance of different vaccine policies that target remaining serogroups. Here, we estimate the health impact and cost associated with several alternative vaccination policies in Burkina Faso. METHODS AND FINDINGS We developed and calibrated a mathematical model of meningococcal transmission to project the disability-adjusted life years (DALYs) averted and costs associated with the current Base policy (serogroup A conjugate vaccination at 9 months, as part of the Expanded Program on Immunization [EPI], plus district-specific reactive vaccination campaigns using polyvalent meningococcal polysaccharide [PMP] vaccine in response to outbreaks) and three alternative policies: (1) Base Prime: novel polyvalent meningococcal conjugate (PMC) vaccine replaces the serogroup A conjugate in EPI and is also used in reactive campaigns; (2) Prevention 1: PMC used in EPI and in a nationwide catch-up campaign for 1-18-year-olds; and (3) Prevention 2: Prevention 1, except the nationwide campaign includes individuals up to 29 years old. Over a 30-year simulation period, Prevention 2 would avert 78% of the meningococcal cases (95% prediction interval: 63%-90%) expected under the Base policy if serogroup A is not replaced by remaining serogroups after elimination, and would avert 87% (77%-93%) of meningococcal cases if complete strain replacement occurs. Compared to the Base policy and at the PMC vaccine price of US$4 per dose, strategies that use PMC vaccine (i.e., Base Prime and Preventions 1 and 2) are expected to be cost saving if strain replacement occurs, and would cost US$51 (-US$236, US$490), US$188 (-US$97, US$626), and US$246 (-US$53, US$703) per DALY averted, respectively, if strain replacement does not occur. An important potential limitation of our study is the simplifying assumption that all circulating meningococcal serogroups can be aggregated into a single group; while this assumption is critical for model tractability, it would compromise the insights derived from our model if the effectiveness of the vaccine differs markedly between serogroups or if there are complex between-serogroup interactions that influence the frequency and magnitude of future meningitis epidemics. CONCLUSIONS Our results suggest that a vaccination strategy that includes a catch-up nationwide immunization campaign in young adults with a PMC vaccine and the addition of this new vaccine into EPI is cost-effective and would avert a substantial portion of meningococcal cases expected under the current World Health Organization-recommended strategy of reactive vaccination. This analysis is limited to Burkina Faso and assumes that polyvalent vaccines offer equal protection against all meningococcal serogroups; further studies are needed to evaluate the robustness of this assumption and applicability for other countries in the meningitis belt.
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Affiliation(s)
- Reza Yaesoubi
- Department of Health Policy and Management, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Caroline Trotter
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Caroline Colijn
- Department of Mathematics, Imperial College London, London, United Kingdom
- Centre for Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
| | - Maziar Yaesoubi
- Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico, United States of America
| | | | - Stephen Resch
- Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Paul A. Kristiansen
- Department of Bacteriology, Norwegian Institute of Public Health, Oslo, Norway
| | | | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
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17
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Al-Darabsah I, Yuan Y. A periodic disease transmission model with asymptomatic carriage and latency periods. J Math Biol 2017; 77:343-376. [PMID: 29274002 DOI: 10.1007/s00285-017-1199-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 12/13/2017] [Indexed: 11/28/2022]
Abstract
In this paper, the global dynamics of a periodic disease transmission model with two delays in incubation and asymptomatic carriage periods is investigated. We first derive the model system with a general nonlinear incidence rate function by stage-structure. Then, we identify the basic reproduction ratio [Formula: see text] for the model and present numerical algorithm to calculate it. We obtain the global attractivity of the disease-free state when [Formula: see text] and discuss the disease persistence when [Formula: see text]. We also explore the coexistence of endemic state in the nonautonomous system and prove the uniqueness with constants coefficients. Numerical simulations are provided to present a case study regarding the meningococcal meningitis disease transmission and discuss the influence of carriers on [Formula: see text].
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Affiliation(s)
- Isam Al-Darabsah
- Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada
| | - Yuan Yuan
- Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
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18
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Mueller JE, Woringer M, Porgho S, Madec Y, Tall H, Martiny N, Bicaba BW. The association between respiratory tract infection incidence and localised meningitis epidemics: an analysis of high-resolution surveillance data from Burkina Faso. Sci Rep 2017; 7:11570. [PMID: 28912442 PMCID: PMC5599514 DOI: 10.1038/s41598-017-11889-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/30/2017] [Indexed: 12/03/2022] Open
Abstract
Meningococcal meningitis epidemics in the African meningitis belt consist of localised meningitis epidemics (LME) that reach attack proportions of 1% within a few weeks. A meningococcal serogroup A conjugate vaccine was introduced in meningitis belt countries from 2010 on, but LME due to other serogroups continue to occur. The mechanisms underlying LME are poorly understood, but an association with respiratory pathogens has been hypothesised. We analysed national routine surveillance data in high spatial resolution (health centre level) from 13 districts in Burkina Faso, 2004–2014. We defined LME as a weekly incidence rate of suspected meningitis ≥75 per 100,000 during ≥2 weeks; and high incidence episodes of respiratory tract infections (RTI) as the 5th quintile of monthly incidences. We included 10,334 health centre month observations during the meningitis season (January-May), including 85 with LME, and 1891 (1820) high-incidence episodes of upper (lower) RTI. In mixed effects logistic regression accounting for spatial structure, and controlling for dust conditions, relative air humidity and month, the occurrence of LME was strongly associated with high incidence episodes of upper (odds ratio 23.9, 95%-confidence interval 3.1–185.3), but not lower RTI. In the African meningitis belt, meningitis epidemics may be triggered by outbreaks of upper RTI.
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Affiliation(s)
- Judith E Mueller
- EHESP French School of Public Health, Sorbonne Paris Cité, Paris, France. .,Institut Pasteur, Paris, France.
| | | | - Souleymane Porgho
- Direction de la lutte contre la maladie, Ministry of Health, Ouagadougou, Burkina Faso
| | | | - Haoua Tall
- Agence de Médecine Préventive, Ouagadougou, Burkina Faso
| | - Nadège Martiny
- UMR6282 BIOGEOSCIENCES, University of Burgundy, Dijon, France
| | - Brice W Bicaba
- Direction de la lutte contre la maladie, Ministry of Health, Ouagadougou, Burkina Faso
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19
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Agier L, Martiny N, Thiongane O, Mueller JE, Paireau J, Watkins ER, Irving TJ, Koutangni T, Broutin H. Towards understanding the epidemiology of Neisseria meningitidis in the African meningitis belt: a multi-disciplinary overview. Int J Infect Dis 2016; 54:103-112. [PMID: 27826113 DOI: 10.1016/j.ijid.2016.10.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/21/2016] [Accepted: 10/29/2016] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVES Neisseria meningitidis is the major cause of seasonal meningitis epidemics in the African meningitis belt. In the changing context of a reduction in incidence of serogroup A and an increase in incidence of serogroups W and C and of Streptococcus pneumoniae, a better understanding of the determinants driving the disease transmission dynamics remains crucial to improving bacterial meningitis control. METHODS The literature was searched to provide a multi-disciplinary overview of the determinants of meningitis transmission dynamics in the African meningitis belt. RESULTS Seasonal hyperendemicity is likely predominantly caused by increased invasion rates, sporadic localized epidemics by increased transmission rates, and larger pluri-annual epidemic waves by changing population immunity. Carriage likely involves competition for colonization and cross-immunity. The duration of immunity likely depends on the acquisition type. Major risk factors include dust and low humidity, and presumably human contact rates and co-infections; social studies highlighted environmental and dietary factors, with supernatural explanations. CONCLUSIONS Efforts should focus on implementing multi-country, longitudinal seroprevalence and epidemiological studies, validating immune markers of protection, and improving surveillance, including more systematic molecular characterizations of the bacteria. Integrating climate and social factors into disease control strategies represents a high priority for optimizing the public health response and anticipating the geographic evolution of the African meningitis belt.
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Affiliation(s)
- Lydiane Agier
- Combining Health Information, Computation and Statistics, Lancaster Medical School, Lancaster University, Lancaster, UK.
| | - Nadège Martiny
- Centre de Recherches de Climatologie (CRC), UMR 6282 CNRS Biogeosciences, Université de Bourgogne, Dijon, France
| | - Oumy Thiongane
- Institut de Recherche pour le Développement, UMR INTERTRYP IRD-CIRAD, Antenne IRD Bobo Dioulasso, Bobo, Burkina Faso
| | - Judith E Mueller
- EHESP French School of Public Health, Sorbonne Paris Cité, Rennes, France; Unité de l'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France
| | - Juliette Paireau
- Unité de l'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France; Department of Ecology and Evolutionary Biology, Princeton Environmental Institute, Princeton University, Princeton, New Jersey, USA
| | | | - Tom J Irving
- School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Thibaut Koutangni
- EHESP French School of Public Health, Sorbonne Paris Cité, Rennes, France; Unité de l'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France
| | - Hélène Broutin
- MIVEGEC, UMR 590CNRS/224IRD/UM, Montpellier, France; Service de Parasitologie-Mycologie, Faculté de Médecine, Université Cheikh Anta Diop, Fann, Dakar, Senegal
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20
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Karachaliou A, Conlan AJK, Preziosi MP, Trotter CL. Modeling Long-term Vaccination Strategies With MenAfriVac in the African Meningitis Belt. Clin Infect Dis 2015; 61 Suppl 5:S594-600. [PMID: 26553693 PMCID: PMC4639487 DOI: 10.1093/cid/civ508] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The introduction of MenAfriVac in campaigns targeting people aged 1-29 years across the African meningitis belt has successfully reduced meningitis incidence and carriage due to Neisseria meningitidis group A (MenA). It is important to consider how best to sustain population protection in the long term. METHODS We created a mathematical model of MenA transmission and disease to investigate the potential impact of a range of immunization strategies. The model is age structured; includes classes of susceptible, carrier, ill, and immune people (who may be vaccinated or unvaccinated); and incorporates seasonal transmission and a stochastic forcing term that models between year variation in rates of transmission. Model parameters were primarily derived from African sources. The model can describe the typical annual incidence of meningitis in the prevaccine era, with irregular epidemics of varying size. Parameter and structural uncertainty were explored in sensitivity analyses. RESULTS Following MenAfriVac introduction at high uptake, the model predicts excellent short-term disease control. With no subsequent immunization, strong resurgences in disease incidence were predicted after approximately 15 years (assuming 10 years' average vaccine protection). Routine immunization at 9 months of age resulted in lower average annual incidence than regular mass campaigns of 1- to 4-year-olds, provided coverage was above approximately 60%. The strategy with the lowest overall average annual incidence and longest time to resurgence was achieved using a combination strategy of introduction into the Expanded Programme on Immunization at 9 months, 5 years after the initial mass campaigns, with a catch-up targeting unvaccinated 1- to 4-year-olds. CONCLUSIONS These results can be used to inform policy recommendations for long-term vaccination strategies with MenAfriVac.
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Affiliation(s)
- Andromachi Karachaliou
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, United Kingdom
| | - Andrew J. K. Conlan
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, United Kingdom
| | - Marie-Pierre Preziosi
- Meningitis Vaccine Project, PATH, Ferney-Voltaire, France
- Meningitis Vaccine Project, Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland
| | - Caroline L. Trotter
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, United Kingdom
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21
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Koutangni T, Boubacar Maïnassara H, Mueller JE. Incidence, carriage and case-carrier ratios for meningococcal meningitis in the African meningitis belt: a systematic review and meta-analysis. PLoS One 2015; 10:e0116725. [PMID: 25658307 PMCID: PMC4319942 DOI: 10.1371/journal.pone.0116725] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 12/12/2014] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND To facilitate the interpretation of meningococcal meningitis epidemiology in the "African meningitis belt", we aimed at obtaining serogroup-specific pooled estimates of incidence, carriage and case-carrier ratios for meningococcal meningitis in the African meningitis belt and describe their variations across the endemic, hyperendemic and epidemic context. METHODS We conducted a systematic review and meta-analysis of studies reporting serogroup-specific meningococcal meningitis monthly incidence and carriage in the same population and time period. Epidemiological contexts were defined as endemic (wet season, no epidemic), hyperendemic (dry season, no epidemic), and epidemic (dry season, epidemic). FINDINGS Eight studies reporting a total of eighty pairs of serogroup-specific meningococcal meningitis incidence and carriage estimates were included in this review. For serogroup A, changes associated with the transition from endemic to hyperendemic incidence and from hyperendemic to epidemic incidence were 15-fold and 120-fold respectively. Changes in carriage prevalence associated with both transitions were 1-fold and 30-fold respectively.
For serogroup W and X, the transition from endemic to hyperendemic incidence involved a 4-fold and 1•1-fold increase respectively. Increases in carriage prevalence for the later transition were 7-fold and 1•7-fold respectively. No data were available for the hyperendemic-epidemic transition for these serogroups. Our findings suggested that the regular seasonal variation in serogroup A meningococcal meningitis incidence between the rainy and the dry season could be mainly driven by seasonal change in the ratio of clinical cases to subclinical infections. In contrast appearance of epidemic incidences is related to a substantial increase in transmission and colonisation and to lesser extent with changes in the case-carrier ratio. CONCLUSION Seasonal change in the rate of progression to disease given carriage together with variations in frequency of carriage transmission should be considered in models attempting to capture the epidemiology of meningococcal meningitis and mainly to predict meningitis epidemics in the African meningitis belt.
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Affiliation(s)
- Thibaut Koutangni
- EHESP French School of Public Health, Sorbonne Paris Cité, Rennes, France
- Institut Pasteur, Emerging Diseases Epidemiology Unit, Paris, France
| | | | - Judith E. Mueller
- EHESP French School of Public Health, Sorbonne Paris Cité, Rennes, France
- Institut Pasteur, Emerging Diseases Epidemiology Unit, Paris, France
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Zimmermann S, Lepenies B. Glycans as Vaccine Antigens and Adjuvants: Immunological Considerations. Methods Mol Biol 2015; 1331:11-26. [PMID: 26169732 DOI: 10.1007/978-1-4939-2874-3_2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Carbohydrates can be found on the cell surface of nearly every cell ranging from bacteria to fungi right up to mammalian cells. Carbohydrates and their interactions with carbohydrate-binding proteins play crucial roles in multiple biological processes including immunity, homeostasis, cellular communication, cell migration, and the regulation of serum glycoprotein levels. In the last decades, the interest in exploiting the biological activity of glycans as vaccine components has considerably increased. On the one hand, carbohydrates display epitopes to generate protective antibodies against pathogen-derived cell wall structures and on the other hand, glycans have the potential to stimulate the immune system; thus they can act as potent vaccine adjuvants.An effective vaccine consists of two major components, the vaccine antigen and an adjuvant. The vaccine antigen is an original or modified part of the pathogen that causes the disease. The immune response triggered by vaccination should induce antigen-specific plasma cells secreting protective antibodies as well as the development of memory T and B cells. Carbohydrate structures on pathogens represent an important class of antigens that can activate B cells to produce protective anti-carbohydrate antibodies in adults. A major breakthrough in vaccine development was the design of conjugate vaccines that evoke protective antibody responses against encapsulated bacteria strains such as Haemophilus influenzae, Streptococcus pneumoniae, or Neisseria meningitidis in adults, but also in young children. The first part of this chapter focuses on immune responses triggered by carbohydrate-based vaccines. The second part of the chapter discusses the immunological mechanisms of carbohydrate-based adjuvants to increase the immunogenicity of vaccines.
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Affiliation(s)
- Stephanie Zimmermann
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany,
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Wall EC, Everett DB, Mukaka M, Bar-Zeev N, Feasey N, Jahn A, Moore M, van Oosterhout JJ, Pensalo P, Baguimira K, Gordon SB, Molyneux EM, Carrol ED, French N, Molyneux ME, Heyderman RS. Bacterial meningitis in Malawian adults, adolescents, and children during the era of antiretroviral scale-up and Haemophilus influenzae type b vaccination, 2000-2012. Clin Infect Dis 2014; 58:e137-45. [PMID: 24496208 PMCID: PMC4001285 DOI: 10.1093/cid/ciu057] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/18/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND We documented bacterial meningitis trends among adults and children presenting to a large teaching hospital in Malawi during introduction of Haemophilus influenzae type b (Hib) vaccination and the rollout of antiretroviral therapy (ART). METHODS We analyzed data from 51 000 consecutive cerebrospinal fluid (CSF) samples obtained from adults, adolescents, and children with suspected meningitis admitted to the Queen Elizabeth Central Hospital, Blantyre, Malawi, between 2000 and 2012. RESULTS There was a significant decline in the total number of CSF isolates over 12 years (incident rate ratio [IRR], 0.93; 95% CI, .92-.94; P < .001). This decline was entirely in children aged <5 years (IRR, 0.87; 95% CI, .85-.88; P < .001) and coincided with the introduction of Hib vaccination. The number of adult isolates has remained unchanged (IRR, 0.99; 95% CI, .97-1.0; P = .135) despite rapid scale-up of ART provision. In children aged <5 years, Streptococcus pneumoniae, nontyphoidal salmonellae (NTS), and Hib were the most frequently isolated pathogens, and have declined over this time period. Streptococcus pneumoniae was the most frequently isolated pathogen in older children and adults. Estimated incidence of bacterial meningitis in 2012 was 20 per 100,000 cases in children aged <14 years, 6 per 100,000 adolescents, and 10 per 100,000 adults. CONCLUSIONS Rates of bacterial meningitis have declined in children, but not adults, coinciding with the introduction of Hib vaccination. The highly successful rollout of ART has not yet resulted in a reduction in the incidence in adults where the burden remains high. Long-term surveillance of bacterial meningitis outside of the epidemic "meningitis belt" in Africa is essential.
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MESH Headings
- Adolescent
- Adult
- Antiretroviral Therapy, Highly Active
- Bacterial Capsules
- Cerebrospinal Fluid/microbiology
- Child
- Child, Preschool
- Drug Utilization
- HIV Infections/complications
- HIV Infections/epidemiology
- Haemophilus Vaccines
- Haemophilus influenzae type b/isolation & purification
- Humans
- Incidence
- Infant
- Malawi/epidemiology
- Meningitis, Bacterial/cerebrospinal fluid
- Meningitis, Bacterial/complications
- Meningitis, Bacterial/epidemiology
- Meningitis, Bacterial/microbiology
- Meningitis, Haemophilus/complications
- Meningitis, Haemophilus/epidemiology
- Meningitis, Haemophilus/microbiology
- Meningitis, Meningococcal/complications
- Meningitis, Meningococcal/epidemiology
- Meningitis, Pneumococcal/complications
- Meningitis, Pneumococcal/epidemiology
- Meningitis, Pneumococcal/microbiology
- Streptococcus pneumoniae/isolation & purification
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Affiliation(s)
- Emma C Wall
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Blantyre, Malawi
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Paireau J, Maïnassara HB, Jusot JF, Collard JM, Idi I, Moulia-Pelat JP, Mueller JE, Fontanet A. Spatio-temporal factors associated with meningococcal meningitis annual incidence at the health centre level in Niger, 2004-2010. PLoS Negl Trop Dis 2014; 8:e2899. [PMID: 24852960 PMCID: PMC4031065 DOI: 10.1371/journal.pntd.0002899] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 04/13/2014] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Epidemics of meningococcal meningitis (MM) recurrently strike the African Meningitis Belt. This study aimed at investigating factors, still poorly understood, that influence annual incidence of MM serogroup A, the main etiologic agent over 2004-2010, at a fine spatial scale in Niger. METHODOLOGY/PRINCIPAL FINDINGS To take into account data dependencies over space and time and control for unobserved confounding factors, we developed an explanatory Bayesian hierarchical model over 2004-2010 at the health centre catchment area (HCCA) level. The multivariate model revealed that both climatic and non-climatic factors were important for explaining spatio-temporal variations in incidence: mean relative humidity during November-June over the study region (posterior mean Incidence Rate Ratio (IRR) = 0.656, 95% Credible Interval (CI) 0.405-0.949) and occurrence of early rains in March in a HCCA (IRR = 0.353, 95% CI 0.239-0.502) were protective factors; a higher risk was associated with the percentage of neighbouring HCCAs having at least one MM A case during the same year (IRR = 2.365, 95% CI 2.078-2.695), the presence of a road crossing the HCCA (IRR = 1.743, 95% CI 1.173-2.474) and the occurrence of cases before 31 December in a HCCA (IRR = 6.801, 95% CI 4.004-10.910). At the study region level, higher annual incidence correlated with greater geographic spread and, to a lesser extent, with higher intensity of localized outbreaks. CONCLUSIONS Based on these findings, we hypothesize that spatio-temporal variability of MM A incidence between years and HCCAs result from variations in the intensity or duration of the dry season climatic effects on disease risk, and is further impacted by factors of spatial contacts, representing facilitated pathogen transmission. Additional unexplained factors may contribute to the observed incidence patterns and should be further investigated.
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Affiliation(s)
- Juliette Paireau
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France
- Univ. Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France
| | - Halima B. Maïnassara
- Unité d'Epidémiologie/Santé-Environnement-Climat, Centre de Recherche Médicale et Sanitaire (CERMES)/Réseau International des Instituts Pasteur, Niamey, Niger
| | - Jean-François Jusot
- Unité d'Epidémiologie/Santé-Environnement-Climat, Centre de Recherche Médicale et Sanitaire (CERMES)/Réseau International des Instituts Pasteur, Niamey, Niger
| | - Jean-Marc Collard
- Unité de Biologie, Centre de Recherche Médicale et Sanitaire (CERMES)/Réseau International des Instituts Pasteur, Niamey, Niger
| | - Issa Idi
- Unité d'Epidémiologie/Santé-Environnement-Climat, Centre de Recherche Médicale et Sanitaire (CERMES)/Réseau International des Instituts Pasteur, Niamey, Niger
| | - Jean-Paul Moulia-Pelat
- Unité d'Epidémiologie/Santé-Environnement-Climat, Centre de Recherche Médicale et Sanitaire (CERMES)/Réseau International des Instituts Pasteur, Niamey, Niger
| | - Judith E. Mueller
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France
- EHESP French School of Public Health, Sorbonne Paris Cité, Rennes, France
| | - Arnaud Fontanet
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France
- Conservatoire National des Arts et Métiers, Chaire Santé et Développement, Paris, France
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25
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Tartof S, Cohn A, Tarbangdo F, Djingarey MH, Messonnier N, Clark TA, Kambou JL, Novak R, Diomandé FVK, Medah I, Jackson ML. Identifying optimal vaccination strategies for serogroup A Neisseria meningitidis conjugate vaccine in the African meningitis belt. PLoS One 2013; 8:e63605. [PMID: 23671685 PMCID: PMC3650081 DOI: 10.1371/journal.pone.0063605] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 04/03/2013] [Indexed: 12/30/2022] Open
Abstract
Objective The optimal long-term vaccination strategies to provide population-level protection against serogroup A Neisseria meningitidis (MenA) are unknown. We developed an age-structured mathematical model of MenA transmission, colonization, and disease in the African meningitis belt, and used this model to explore the impact of various vaccination strategies. Methods The model stratifies the simulated population into groups based on age, infection status, and MenA antibody levels. We defined the model parameters (such as birth and death rates, age-specific incidence rates, and age-specific duration of protection) using published data and maximum likelihood estimation. We assessed the validity of the model by comparing simulated incidence of invasive MenA and prevalence of MenA carriage to observed incidence and carriage data. Results The model fit well to observed age- and season-specific prevalence of carriage (mean pseudo-R2 0.84) and incidence of invasive disease (mean R2 0.89). The model is able to reproduce the observed dynamics of MenA epidemics in the African meningitis belt, including seasonal increases in incidence, with large epidemics occurring every eight to twelve years. Following a mass vaccination campaign of all persons 1–29 years of age, the most effective modeled vaccination strategy is to conduct mass vaccination campaigns every 5 years for children 1–5 years of age. Less frequent campaigns covering broader age groups would also be effective, although somewhat less so. Introducing conjugate MenA vaccine into the EPI vaccination schedule at 9 months of age results in higher predicted incidence than periodic mass campaigns. Discussion We have developed the first mathematical model of MenA in Africa to incorporate age structures and progressively waning protection over time. Our model accurately reproduces key features of MenA epidemiology in the African meningitis belt. This model can help policy makers consider vaccine program effectiveness when determining the feasibility and benefits of MenA vaccination strategies.
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Affiliation(s)
- Sara Tartof
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
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26
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Trotter CL, Yaro S, Njanpop-Lafourcade BM, Drabo A, Kroman SS, Idohou RS, Sanou O, Bowen L, Findlow H, Diagbouga S, Gessner BD, Borrow R, Mueller JE. Seroprevalence of bactericidal, specific IgG antibodies and incidence of meningitis due to group A Neisseria meningitidis by age in Burkina Faso 2008. PLoS One 2013; 8:e55486. [PMID: 23457471 PMCID: PMC3573051 DOI: 10.1371/journal.pone.0055486] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/27/2012] [Indexed: 01/17/2023] Open
Abstract
Background We investigated serological correlates of protection against Neisseria meningitidis serogroup A (NmA) in Burkina Faso before the introduction of NmA conjugate vaccine. Methodology/Principal Findings We collected blood from a representative sample (N = 1022) of Bobo-Dioulasso residents. Sera were evaluated for serum bactericidal antibody (SBA) activity against NmA strains of immunotype L11 (F8238) and L10 (3125) and NmA-specific IgG. Seroprevalence was compared to the age-specific NmA meningitis incidence in Bobo-Dioulasso during March 2007–February 2008. Meningococcal carriage was evaluated in a subset (N = 538). Geometric mean titres (GMT)/concentrations (GMC) of SBA and NmA-specific IgG increased with age, peaking around age 20 years. Overall, 70% of our sample had NmA-specific IgG ≥2 ug/mL. Meningitis incidence was highest in those aged <6 months and 5–19 years. No NmA carriers were found. Compared to the reference strain SBA, GMTs were higher against a locally isolated strain and around 40-fold lower against Dutch strain 3125. Conclusions/Significance This study provides estimates of natural immunity to NmA, according to a variety of antibody measures, which will be helpful in ascertaining antibody persistence after MenAfriVac™ introduction. Age-specific seroprevalence of reference strain SBA titres most likely reflects exposure to meningococci and consecutive reactive immunity. We could not define any serological correlate of protection.
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Affiliation(s)
- Caroline L Trotter
- School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
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27
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Agier L, Deroubaix A, Martiny N, Yaka P, Djibo A, Broutin H. Seasonality of meningitis in Africa and climate forcing: aerosols stand out. J R Soc Interface 2012; 10:20120814. [PMID: 23221989 DOI: 10.1098/rsif.2012.0814] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bacterial meningitis is an ongoing threat for the population of the African Meningitis Belt, a region characterized by the highest incidence rates worldwide. The determinants of the disease dynamics are still poorly understood; nevertheless, it is often advocated that climate and mineral dust have a large impact. Over the last decade, several studies have investigated this relationship at a large scale. In this analysis, we scaled down to the district-level weekly scale (which is used for in-year response to emerging epidemics), and used wavelet and phase analysis methods to define and compare the time-varying periodicities of meningitis, climate and dust in Niger. We mostly focused on detecting time-lags between the signals that were consistent across districts. Results highlighted the special case of dust in comparison to wind, humidity or temperature: a strong similarity between districts is noticed in the evolution of the time-lags between the seasonal component of dust and meningitis. This result, together with the assumption of dust damaging the pharyngeal mucosa and easing bacterial invasion, reinforces our confidence in dust forcing on meningitis seasonality. Dust data should now be integrated in epidemiological and forecasting models to make them more realistic and usable in a public health perspective.
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Affiliation(s)
- L Agier
- Combining Health Information, Computation and Statistics, School of Health and Medicine, Lancaster University, Lancaster, UK.
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Simell B, Auranen K, Käyhty H, Goldblatt D, Dagan R, O'Brien KL. The fundamental link between pneumococcal carriage and disease. Expert Rev Vaccines 2012; 11:841-55. [PMID: 22913260 DOI: 10.1586/erv.12.53] [Citation(s) in RCA: 451] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is a major cause of worldwide mortality and morbidity, and to a large extent is vaccine-preventable. Nasopharyngeal carriage of pneumococcus precedes disease and is the source of pneumococcal spread between people. The use of vaccine effect on carriage as part of the vaccine licensure and post-vaccine introduction evaluation could facilitate and expand the licensure of new, life-saving pneumococcal vaccines and enable a comprehensive estimate of population effects after vaccine introduction. The authors provide a review of the evidence supporting pneumococcal carriage at the individual level as an immediate and necessary precursor to pneumococcal disease. Based on such a causal link between carriage and disease, the authors emphasize the role of information on pneumococcal carriage in vaccine trials and in public health decision-making.
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Affiliation(s)
- Birgit Simell
- Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland
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A multi-state spatio-temporal Markov model for categorized incidence of meningitis in sub-Saharan Africa. Epidemiol Infect 2012; 141:1764-71. [PMID: 22995184 DOI: 10.1017/s0950268812001926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Meningococcal meningitis is a major public health problem in the African Belt. Despite the obvious seasonality of epidemics, the factors driving them are still poorly understood. Here, we provide a first attempt to predict epidemics at the spatio-temporal scale required for in-year response, using a purely empirical approach. District-level weekly incidence rates for Niger (1986-2007) were discretized into latent, alert and epidemic states according to pre-specified epidemiological thresholds. We modelled the probabilities of transition between states, accounting for seasonality and spatio-temporal dependence. One-week-ahead predictions for entering the epidemic state were generated with specificity and negative predictive value >99%, sensitivity and positive predictive value >72%. On the annual scale, we predict the first entry of a district into the epidemic state with sensitivity 65∙0%, positive predictive value 49∙0%, and an average time gained of 4∙6 weeks. These results could inform decisions on preparatory actions.
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Paireau J, Girond F, Collard JM, Maïnassara HB, Jusot JF. Analysing spatio-temporal clustering of meningococcal meningitis outbreaks in Niger reveals opportunities for improved disease control. PLoS Negl Trop Dis 2012; 6:e1577. [PMID: 22448297 PMCID: PMC3308932 DOI: 10.1371/journal.pntd.0001577] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 02/09/2012] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Meningococcal meningitis is a major health problem in the "African Meningitis Belt" where recurrent epidemics occur during the hot, dry season. In Niger, a central country belonging to the Meningitis Belt, reported meningitis cases varied between 1,000 and 13,000 from 2003 to 2009, with a case-fatality rate of 5-15%. METHODOLOGY/PRINCIPAL FINDINGS In order to gain insight in the epidemiology of meningococcal meningitis in Niger and to improve control strategies, the emergence of the epidemics and their diffusion patterns at a fine spatial scale have been investigated. A statistical analysis of the spatio-temporal distribution of confirmed meningococcal meningitis cases was performed between 2002 and 2009, based on health centre catchment areas (HCCAs) as spatial units. Anselin's local Moran's I test for spatial autocorrelation and Kulldorff's spatial scan statistic were used to identify spatial and spatio-temporal clusters of cases. Spatial clusters were detected every year and most frequently occurred within nine southern districts. Clusters most often encompassed few HCCAs within a district, without expanding to the entire district. Besides, strong intra-district heterogeneity and inter-annual variability in the spatio-temporal epidemic patterns were observed. To further investigate the benefit of using a finer spatial scale for surveillance and disease control, we compared timeliness of epidemic detection at the HCCA level versus district level and showed that a decision based on threshold estimated at the HCCA level may lead to earlier detection of outbreaks. CONCLUSIONS/SIGNIFICANCE Our findings provide an evidence-based approach to improve control of meningitis in sub-Saharan Africa. First, they can assist public health authorities in Niger to better adjust allocation of resources (antibiotics, rapid diagnostic tests and medical staff). Then, this spatio-temporal analysis showed that surveillance at a finer spatial scale (HCCA) would be more efficient for public health response: outbreaks would be detected earlier and reactive vaccination would be better targeted.
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Affiliation(s)
- Juliette Paireau
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France.
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