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Ofori SK, Schwind JS, Sullivan KL, Chowell G, Cowling BJ, Fung ICH. Modeling the health impact of increasing vaccine coverage and nonpharmaceutical interventions against coronavirus disease 2019 in Ghana. Pathog Glob Health 2024:1-15. [PMID: 38318877 DOI: 10.1080/20477724.2024.2313787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
Seroprevalence studies assessing community exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Ghana concluded that population-level immunity remained low as of February 2021. Thus, it is important to demonstrate how increasing vaccine coverage reduces the economic and public health impacts associated with SARS-CoV-2 transmission. To that end, this study used a Susceptible-Exposed-Presymptomatic-Symptomatic-Asymptomatic-Recovered-Dead-Vaccinated compartmental model to simulate coronavirus disease 2019 (COVID-19) transmission and the role of public health interventions in Ghana. The impact of increasing vaccination rates and decline in transmission rates due to nonpharmaceutical interventions (NPIs) on cumulative infections and deaths averted was explored under different scenarios. Latin hypercube sampling-partial rank correlation coefficient (LHS-PRCC) was used to investigate the uncertainty and sensitivity of the outcomes to the parameters. Simulation results suggest that increasing the vaccination rate to achieve 50% coverage was associated with almost 60,000 deaths and 25 million infections averted. In comparison, a 50% decrease in the transmission coefficient was associated with the prevention of about 150,000 deaths and 50 million infections. The LHS-PRCC results indicated that in the context of vaccination rate, cumulative infections and deaths averted were most sensitive to vaccination rate, waning immunity rates from vaccination, and waning immunity from natural infection. This study's findings illustrate the impact of increasing vaccination coverage and/or reducing the transmission rate by NPI adherence in the prevention of COVID-19 infections and deaths in Ghana.
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Affiliation(s)
- Sylvia K Ofori
- Department of Biostatistics, Epidemiology and Environmental Health Sciences, Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, Georgia
| | - Jessica S Schwind
- Institute for Health Logistics & Analytics, Georgia Southern University, Statesboro, Georgia
| | - Kelly L Sullivan
- Department of Biostatistics, Epidemiology and Environmental Health Sciences, Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, Georgia
| | - Gerardo Chowell
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, Georgia
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Isaac Chun-Hai Fung
- Department of Biostatistics, Epidemiology and Environmental Health Sciences, Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, Georgia
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John RS, Miller JC, Muylaert RL, Hayman DTS. High connectivity and human movement limits the impact of travel time on infectious disease transmission. J R Soc Interface 2024; 21:20230425. [PMID: 38196378 PMCID: PMC10777149 DOI: 10.1098/rsif.2023.0425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 12/08/2023] [Indexed: 01/11/2024] Open
Abstract
The speed of spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the coronavirus disease 2019 (COVID-19) pandemic highlights the importance of understanding how infections are transmitted in a highly connected world. Prior to vaccination, changes in human mobility patterns were used as non-pharmaceutical interventions to eliminate or suppress viral transmission. The rapid spread of respiratory viruses, various intervention approaches, and the global dissemination of SARS-CoV-2 underscore the necessity for epidemiological models that incorporate mobility to comprehend the spread of the virus. Here, we introduce a metapopulation susceptible-exposed-infectious-recovered model parametrized with human movement data from 340 cities in China. Our model replicates the early-case trajectory in the COVID-19 pandemic. We then use machine learning algorithms to determine which network properties best predict spread between cities and find travel time to be most important, followed by the human movement-weighted personalized PageRank. However, we show that travel time is most influential locally, after which the high connectivity between cities reduces the impact of travel time between individual cities on transmission speed. Additionally, we demonstrate that only significantly reduced movement substantially impacts infection spread times throughout the network.
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Affiliation(s)
- Reju Sam John
- Massey University, Palmerston North 4474, New Zealand
- University of Auckland, Auckland 1010, New Zealand
| | - Joel C. Miller
- La Trobe University, Melbourne 3086, Victoria, Australia
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Bents SJ, Viboud C, Grenfell BT, Hogan AB, Tempia S, von Gottberg A, Moyes J, Walaza S, Hansen C, Cohen C, Baker RE. Modeling the impact of COVID-19 nonpharmaceutical interventions on respiratory syncytial virus transmission in South Africa. Influenza Other Respir Viruses 2023; 17:e13229. [PMID: 38090227 PMCID: PMC10710953 DOI: 10.1111/irv.13229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/25/2023] [Accepted: 11/11/2023] [Indexed: 12/18/2023] Open
Abstract
Background The South African government employed various nonpharmaceutical interventions (NPIs) to reduce the spread of SARS-CoV-2. Surveillance data from South Africa indicates reduced circulation of respiratory syncytial virus (RSV) throughout the 2020-2021 seasons. Here, we use a mechanistic transmission model to project the rebound of RSV in the two subsequent seasons. Methods We fit an age-structured epidemiological model to hospitalization data from national RSV surveillance in South Africa, allowing for time-varying reduction in RSV transmission during periods of COVID-19 circulation. We apply the model to project the rebound of RSV in the 2022 and 2023 seasons. Results We projected an early and intense outbreak of RSV in April 2022, with an age shift to older infants (6-23 months old) experiencing a larger portion of severe disease burden than typical. In March 2022, government alerts were issued to prepare the hospital system for this potentially intense outbreak. We then assess the 2022 predictions and project the 2023 season. Model predictions for 2023 indicate that RSV activity has not fully returned to normal, with a projected early and moderately intense wave. We estimate that NPIs reduced RSV transmission between 15% and 50% during periods of COVID-19 circulation. Conclusions A wide range of NPIs impacted the dynamics of the RSV outbreaks throughout 2020-2023 in regard to timing, magnitude, and age structure, with important implications in a low- and middle-income countries (LMICs) setting where RSV interventions remain limited. More efforts should focus on adapting RSV models to LMIC data to project the impact of upcoming medical interventions for this disease.
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Affiliation(s)
- Samantha J. Bents
- Fogarty International Center, National Institutes of HealthBethesdaMarylandUSA
| | - Cécile Viboud
- Fogarty International Center, National Institutes of HealthBethesdaMarylandUSA
| | - Bryan T. Grenfell
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew JerseyUSA
| | - Alexandra B. Hogan
- School of Population HealthUniversity of New South WalesSydneyNew South WalesAustralia
| | - Stefano Tempia
- Centre for Respiratory Diseases and MeningitisNational Institute for Communicable Diseases of the National Health Laboratory ServiceJohannesburgSouth Africa
- School of Public Health, Faculty of Health SciencesUniversity of WitwatersrandJohannesburgSouth Africa
| | - Anne von Gottberg
- Centre for Respiratory Diseases and MeningitisNational Institute for Communicable Diseases of the National Health Laboratory ServiceJohannesburgSouth Africa
- School of Pathology, Faculty of Health SciencesUniversity of WitwatersrandJohannesburgSouth Africa
- Department of Pathology, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Jocelyn Moyes
- Centre for Respiratory Diseases and MeningitisNational Institute for Communicable Diseases of the National Health Laboratory ServiceJohannesburgSouth Africa
- School of Public Health, Faculty of Health SciencesUniversity of WitwatersrandJohannesburgSouth Africa
| | - Sibongile Walaza
- Centre for Respiratory Diseases and MeningitisNational Institute for Communicable Diseases of the National Health Laboratory ServiceJohannesburgSouth Africa
- School of Public Health, Faculty of Health SciencesUniversity of WitwatersrandJohannesburgSouth Africa
| | - Chelsea Hansen
- Fogarty International Center, National Institutes of HealthBethesdaMarylandUSA
- Brotman Baty InstituteUniversity of WashingtonSeattleWashingtonUSA
- PandemiX Center, Department of Science & EnvironmentRoskilde UniversityRoskildeDenmark
| | - Cheryl Cohen
- Centre for Respiratory Diseases and MeningitisNational Institute for Communicable Diseases of the National Health Laboratory ServiceJohannesburgSouth Africa
- School of Public Health, Faculty of Health SciencesUniversity of WitwatersrandJohannesburgSouth Africa
| | - Rachel E. Baker
- School of Public HealthBrown UniversityProvidenceRhode IslandUSA
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Quispe AM, Castagnetto JM. Monkeypox in Latin America and the Caribbean: assessment of the first 100 days of the 2022 outbreak. Pathog Glob Health 2023; 117:717-726. [PMID: 37057838 PMCID: PMC10614714 DOI: 10.1080/20477724.2023.2201979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023] Open
Abstract
During the 2022 monkeypox (mpox) epidemic's first 100 days, 99 non-endemic countries, including 25 Latin American and Caribbean (LAC) countries, reported >64,000 cases. We aim to assess the cases' introduction, epidemiological profile, initial response, transmission dynamics, and main challenges ahead among LAC countries during the first 100 days of the mpox 2022 epidemic. We used mixed methods, including desktop research and open data analysis. The 2022 mpox epidemic has progressed consistently through LAC, with Brazil and Peru combining for over 80% of the confirmed LAC cases. Although Brazil reports the highest mpox case counts (n = 4472), Peru reports the highest incidence (41 confirmed cases per 1 million inhabitants). Initially, LAC missed the opportunity to focus on the high-risk population, including the people living with HIV (PLHIV) and gay, bisexual, and men who have sex with men (GBMSM). Moreover, the main challenges ahead include stigmatization, vaccine inequity, barriers to accessing diagnostics, and complete isolation. Furthermore, we estimated that Colombia, Brazil, the United States, and Peru are the world frontrunners in mpox duplication time (estimated between 6.4 and 8.8) and effective reproductive number (estimated between 2.7 and 3.8). In addition, Brazil reported its first case of inverse zoonosis in a dog and Peru its first autochthonous MPXV lineage, B.1.6. LAC has become the epicenter of the 2022 mpox epidemic, with Brazil and Peru emerging as the new mpox hot zones. Therefore, LAC countries must join efforts to control this epidemic and overcome the challenges of vaccine inequity and stigmatization.
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Vicente-Santos A, Willink B, Nowak K, Civitello DJ, Gillespie TR. Host-pathogen interactions under pressure: A review and meta-analysis of stress-mediated effects on disease dynamics. Ecol Lett 2023; 26:2003-2020. [PMID: 37804128 PMCID: PMC10874615 DOI: 10.1111/ele.14319] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 10/08/2023]
Abstract
Human activities have increased the intensity and frequency of natural stressors and created novel stressors, altering host-pathogen interactions and changing the risk of emerging infectious diseases. Despite the ubiquity of such anthropogenic impacts, predicting the directionality of outcomes has proven challenging. Here, we conduct a review and meta-analysis to determine the primary mechanisms through which stressors affect host-pathogen interactions and to evaluate the impacts stress has on host fitness (survival and fecundity) and pathogen infectivity (prevalence and intensity). We assessed 891 effect sizes from 71 host species (representing seven taxonomic groups) and 78 parasite taxa from 98 studies. We found that infected and uninfected hosts had similar sensitivity to stressors and that responses varied according to stressor type. Specifically, limited resources compromised host fecundity and decreased pathogen intensity, while abiotic environmental stressors (e.g., temperature and salinity) decreased host survivorship and increased pathogen intensity, and pollution increased mortality but decreased pathogen prevalence. We then used our meta-analysis results to develop susceptible-infected theoretical models to illustrate scenarios where infection rates are expected to increase or decrease in response to resource limitations or environmental stress gradients. Our results carry implications for conservation and disease emergence and reveal areas for future work.
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Affiliation(s)
- Amanda Vicente-Santos
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
| | - Beatriz Willink
- Department of Zoology, Stockholm University, Stockholm 106-91, Sweden
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
- School of Biology, University of Costa Rica, San José 11501-2060, Costa Rica
| | - Kacy Nowak
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - David J. Civitello
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Thomas R. Gillespie
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322, USA
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6
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Diakite I, Kyle J, Situ S, Bai P, Zhang X, Wang W, Daniels V. Public health impact of 2-, 4-, and 9-valent HPV vaccination in females on cervical and noncervical diseases in men and women under different coverage scenarios in China: A simulation study. Hum Vaccin Immunother 2023; 19:2258569. [PMID: 37787054 PMCID: PMC10549189 DOI: 10.1080/21645515.2023.2258569] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/09/2023] [Indexed: 10/04/2023] Open
Abstract
The high prevalence of human papillomavirus (HPV) infection in China suggests there would be a substantial positive health impact of widespread vaccination against HPV. We adapted a previously described dynamic transmission model of the natural history of HPV infection and related diseases to the Chinese setting to estimate the public health impact in China of 2-valent (with and without cross-protection), 4-valent, and 9-valent HPV vaccination strategies. The model predicted the incidence and mortality associated with HPV-related diseases, including cervical and noncervical cancers, genital warts, and recurrent respiratory papillomatosis (RRP), based on the various vaccination coverage rate (VCR) scenarios, over a 100-year time horizon. The public health impact of the 4 vaccination strategies was estimated in terms of cases and deaths averted compared to a scenario with no vaccination. Under the assumption of various primary and catch-up VCR scenarios, all 4 vaccination strategies reduced the incidence of cervical cancer in females and noncervical cancers in both sexes, and the 4-valent and 9-valent vaccines reduced the incidence of genital warts and RRP in both sexes. The 9-valent vaccination strategy was superior on all outcomes. The number of cervical cancer cases averted over 100 years ranged from ~ 1 million to ~ 5 million while the number of cervical cancer deaths averted was ~ 345,000 to ~ 1.9 million cases, depending on the VCR scenario. The VCR for primary vaccination was the major driver of cases averted.
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Affiliation(s)
- Ibrahim Diakite
- Biostatistics & Research Decision Sciences, Merck & Co., Inc., Rahway, NJ, USA
| | - Jeffrey Kyle
- Biostatistics & Research Decision Sciences, Merck & Co., Inc., Rahway, NJ, USA
| | | | - Peng Bai
- MSD China Holding Co., Ltd., China
| | | | - Wei Wang
- Biostatistics & Research Decision Sciences, Merck & Co., Inc., Rahway, NJ, USA
| | - Vincent Daniels
- Biostatistics & Research Decision Sciences, Merck & Co., Inc., Rahway, NJ, USA
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McManus O, Christiansen LE, Nauta M, Krogsgaard LW, Bahrenscheer NS, von Kappelgaard L, Christiansen T, Hansen M, Hansen NC, Kähler J, Rasmussen A, Richter SR, Rasmussen LD, Franck KT, Ethelberg S. Predicting COVID-19 Incidence Using Wastewater Surveillance Data, Denmark, October 2021-June 2022. Emerg Infect Dis 2023; 29:1589-1597. [PMID: 37486168 PMCID: PMC10370843 DOI: 10.3201/eid2908.221634] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023] Open
Abstract
Analysis of wastewater is used in many settings for surveillance of SARS-CoV-2, but it remains unclear how well wastewater testing results reflect incidence. Denmark has had an extensive wastewater analysis system that conducts 3 weekly tests in ≈200 sites and has 85% population coverage; the country also offers free SARS-CoV-2 PCR tests to all residents. Using time series analysis for modeling, we found that wastewater data, combined with information on circulating variants and the number of human tests performed, closely fitted the incidence curve of persons testing positive. The results were consistent at a regional level and among a subpopulation of frequently tested healthcare personnel. We used wastewater analysis data to estimate incidence after testing was reduced to a minimum after March 2022. These results imply that data from a large-scale wastewater surveillance system can serve as a good proxy for COVID-19 incidence and for epidemic control.
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8
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Simon S, Amaku M, Massad E. Effects of migration rates and vaccination on the spread of yellow fever in Latin American communities. Rev Panam Salud Publica 2023; 47:e86. [PMID: 37266487 PMCID: PMC10231272 DOI: 10.26633/rpsp.2023.86] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 01/28/2023] [Indexed: 06/03/2023] Open
Abstract
Objective To assess how relevant the flow of people between communities is, compared to vaccination and type of vector, on the spread and potential outbreaks of yellow fever in a disease-free host community. Methods Using a SEIRV-SEI model for humans and vectors, we applied numerical simulations to the scenarios: (1) migration from an endemic community to a disease-free host community, comparing the performance of Haemagogus janthinomys and Aedes aegypti as vectors; (2) migration through a transit community located on a migratory route, where the disease is endemic, to a disease-free one; and (3) effects of different vaccination rates in the host community, considering the vaccination of migrants upon arrival. Results Results show no remarkable differences between scenarios 1 and 2. The type of vector and vaccination coverage in the host community are more relevant for the occurrence of outbreaks than migration rates, with H. janthinomys being more effective than A. aegypti. Conclusions With vaccination being more determinant for a potential outbreak than migration rates, vaccinating migrants on arrival may be one of the most effective measures against yellow fever. Furthermore, H. janthinomys is a more competent vector than A. aegypti at similar densities, but the presence of A. aegypti is a warning to maintain vaccination above recommended levels.
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Affiliation(s)
- Sabrina Simon
- University of São PauloSão PauloBrazilUniversity of São Paulo, São Paulo, Brazil
| | - Marcos Amaku
- University of São PauloSão PauloBrazilUniversity of São Paulo, São Paulo, Brazil
| | - Eduardo Massad
- Getúlio Vargas FoundationRio de JaneiroBrazilGetúlio Vargas Foundation, Rio de Janeiro, Brazil
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9
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Pereyra Irujo G, Velázquez L, Perinetti A. [Quantitative evaluation of a SEIR model for forecasting COVID-19 cases]. Medicina (B Aires) 2023; 83:558-568. [PMID: 37582130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2023] Open
Abstract
INTRODUCTION Epidemiological models have been widely used during the COVID-19 pandemic, although performance evaluation has been limited. The objective of this work was to thoroughly evaluate a SEIR model used for the short-term (1 to 3 weeks) prediction of cases, quantifying its actual past performance, and its potential performance by optimizing the model parameters. METHODS Daily case forecasts were obtained for the first wave of cases (July 31, 2020 to March 11, 2021) in the district of General Pueyrredón (Argentina), quantifying the model performance in terms of uncertainty, inaccuracy and imprecision. The evaluation was carried out with the original parameters of the model (used in the forecasts that were published), and also varying different parameters in order to identify optimal values. RESULTS The analysis of the model performance showed that alternative values of some parameters, and the correction of the input values using a "moving average" filter to eliminate the weekly variations in the case reports, would have yielded better results. The model with the optimized parameters was able to reduce the uncertainty from almost 40% to less than 15%, with similar values of inaccuracy, and with slightly greater imprecision. DISCUSSION Simple epidemiological models, without large requirements for their implementation, can be very useful for making quick decisions in small cities or cities with limited resources, as long as the importance of their evaluation is taken into account and their scope and limitations are considered.
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Affiliation(s)
| | - Luciano Velázquez
- Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Balcarce, Argentina
| | - Andrea Perinetti
- Escuela Superior de Medicina, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. E-mail:
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Ryckman TS, Dowdy DW, Kendall EA. Infectious and clinical tuberculosis trajectories: Bayesian modeling with case finding implications. Proc Natl Acad Sci U S A 2022; 119:e2211045119. [PMID: 36534797 DOI: 10.1073/pnas.2211045119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The importance of finding people with undiagnosed tuberculosis (TB) hinges on their future disease trajectories. Assays for systematic screening should be optimized to find those whose TB will contribute most to future transmission or morbidity. In this study, we constructed a mathematical model that tracks the future trajectories of individuals with TB at a cross-sectional timepoint ("baseline"), classifying them by bacterial burden (smear positive/negative) and symptom status (symptomatic/subclinical). We used Bayesian methods to calibrate this model to targets derived from historical survival data and notification, mortality, and prevalence data from five countries. We combined resulting disease trajectories with evidence on infectiousness to estimate each baseline TB state's contribution to future transmission. For a person with smear-negative subclinical TB at baseline, the expected future duration of disease was short (mean 4.8 [95% uncertainty interval 3.3 to 8.4] mo); nearly all disease courses ended in spontaneous resolution, not treatment. In contrast, people with baseline smear-positive subclinical TB had longer undiagnosed disease durations (15.9 [11.1 to 23.5] mo); nearly all eventually developed symptoms and ended in treatment or death. Despite accounting for only 11 to 19% of prevalent disease, smear-positive subclinical TB accounted for 35 to 51% of future transmission-a greater contribution than symptomatic or smear-negative TB. Subclinical TB with a high bacterial burden accounts for a disproportionate share of future transmission. Priority should be given to developing inexpensive, easy-to-use assays for screening both symptomatic and asymptomatic individuals at scale-akin to rapid antigen tests for other diseases-even if these assays lack the sensitivity to detect paucibacillary disease.
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11
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Lidsky PV, Andino R. Could aging evolve as a pathogen control strategy? Trends Ecol Evol 2022; 37:1046-57. [PMID: 36096982 DOI: 10.1016/j.tree.2022.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 01/12/2023]
Abstract
Aging is often attributed to the detrimental side effects of beneficial traits but not a programmed adaptive process. Alternatively, the pathogen control hypothesis posits that defense against infectious diseases may provide a strong selection force for restriction of lifespan. Aging might have evolved to remove older individuals who carry chronic diseases that may transmit to their younger kin. Thus, selection for shorter lifespans may benefit kin's fitness. The pathogen control hypothesis addresses arguments typically raised against adaptive aging concepts: it explains the benefit of shorter lifespan and the absence of mutant variants that do not age. We discuss the consistency and explanatory power of this hypothesis and compare it with classic hypotheses of aging.
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12
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Doyle CM, Cox J, Milwid RM, Bitera R, Delaunay CL, Alary M, Lambert G, Tremblay C, Mishra S, Maheu-Giroux M. Measuring progress towards reaching zero new HIV acquisitions among key populations in Québec (Canada) using routine surveillance data: a mathematical modelling study. J Int AIDS Soc 2022; 25:e25994. [PMID: 36050916 PMCID: PMC9437443 DOI: 10.1002/jia2.25994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 07/27/2022] [Indexed: 11/25/2022] Open
Abstract
Introduction Men who have sex with men (MSM) and people who inject drugs (PWID) are disproportionately impacted by the HIV epidemic in Canada. Having the second‐highest provincial diagnosis rate, an improved understanding of the epidemic among these populations in Québec could aid ongoing elimination efforts. We estimated HIV incidence and other epidemic indicators among MSM and PWID in Montréal and across Québec using a back‐calculation model synthesizing surveillance data. Methods We developed a deterministic, compartmental mathematical model stratified by age, HIV status and disease progression, and clinical care stages. Using AIDS and HIV diagnoses data, including self‐reported time since the last negative test and laboratory results of CD4 cell count at diagnosis, we estimated HIV incidence in each population over 1975–2020 by modelling a cubic M‐spline. The prevalence, undiagnosed fraction, fraction diagnosed that started antiretroviral treatment (ART) and median time to diagnosis were also estimated. Since the COVID‐19 pandemic disrupted testing, we excluded 2020 data and explored this in sensitivity analyses. Results HIV incidence in all populations peaked early in the epidemic. In 2020, an estimated 97 (95% CrI: 33–227) and 266 (95% CrI: 103–508) HIV acquisitions occurred among MSM in Montréal and Québec, respectively. Among PWID, we estimated 2 (95% CrI: 0–14) and 6 (95% CrI: 1–26) HIV acquisitions in those same regions. With 2020 data, unless testing rates were reduced by 50%, these estimates decreased, except among Québec PWID, whose increased. Among all, the median time to diagnosis shortened to <2 years before 2020 and the undiagnosed fraction decreased to <10%. This fraction was higher in younger MSM, with 22% of 15–24 year‐olds living with HIV in Montréal (95% CrI: 9–39%) and 31% in Québec (95% CrI: 17–48%) undiagnosed by 2020 year‐end. Finally, ART access neared 100% in all diagnosed populations. Conclusions HIV incidence has drastically decreased in MSM and PWID across Québec, alongside significant improvements in diagnosis and treatment coverage—and the 2013 introduction of pre‐exposure prophylaxis. Despite this, HIV transmission continued. Effective efforts to halt this transmission and rapidly diagnose people who acquired HIV, especially among younger MSM, are needed to achieve elimination. Further, as the impacts of the COVID‐19 pandemic on HIV transmission are understood, increased efforts may be needed to overcome these.
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Affiliation(s)
- Carla M Doyle
- Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada
| | - Joseph Cox
- Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada.,Direction Régionale de Santé Publique de Montréal, Montréal, Québec, Canada.,Clinical Outcomes Research and Evaluation, Research Institute - McGill University Health Centre, Montréal, Québec, Canada
| | - Rachael M Milwid
- Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada
| | - Raphaël Bitera
- Institut national de santé publique du Québec, Québec, Québec, Canada
| | - Charlotte Lanièce Delaunay
- Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada.,Clinical Outcomes Research and Evaluation, Research Institute - McGill University Health Centre, Montréal, Québec, Canada
| | - Michel Alary
- Institut national de santé publique du Québec, Québec, Québec, Canada.,Centre de recherche du CHU de Québec - Université Laval, Québec, Québec, Canada.,Département de médecine sociale et préventive, Université Laval, Québec, Québec, Canada
| | - Gilles Lambert
- Direction Régionale de Santé Publique de Montréal, Montréal, Québec, Canada
| | - Cécile Tremblay
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada.,Department of Microbiology, Infectiology and Immunology, University of Montréal, Montréal, Québec, Canada
| | - Sharmistha Mishra
- Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.,Institute of Health Policy Management and Evaluation, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Mathieu Maheu-Giroux
- Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada
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13
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Albani VVL, Albani RAS, Massad E, Zubelli JP. Nowcasting and forecasting COVID-19 waves: the recursive and stochastic nature of transmission. R Soc Open Sci 2022; 9:220489. [PMID: 36016918 PMCID: PMC9399708 DOI: 10.1098/rsos.220489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 08/02/2022] [Indexed: 05/20/2023]
Abstract
We propose a parsimonious, yet effective, susceptible-exposed-infected-removed-type model that incorporates the time change in the transmission and death rates. The model is calibrated by Tikhonov-type regularization from official reports from New York City (NYC), Chicago, the State of São Paulo, in Brazil and British Columbia, in Canada. To forecast, we propose different ways to extend the transmission parameter, considering its estimated values. The forecast accuracy is then evaluated using real data from the above referred places. All the techniques accurately provided forecast scenarios for periods 15 days long. One of the models effectively predicted the magnitude of the four waves of infections in NYC, including the one caused by the Omicron variant for periods of 45 days using out-of-sample data.
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Affiliation(s)
- V. V. L. Albani
- Department of Mathematics, Federal University of Santa Catarina, Florianopolis, Brazil
| | - R. A. S. Albani
- Instituto Politecnico do Rio de Janeiro, Rio de Janeiro State University, Nova Friburgo, Brazil
| | - E. Massad
- School of Medicine, University of São Paulo and LIM01-HCFMUSP, São Paulo, Brazil
- School of Applied Mathematics, Fundação Getúlio Vargas, Rio de Janeiro, Brazil
| | - J. P. Zubelli
- Mathematics Department, Khalifa University, Abu Dhabi, UAE
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14
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Ito C, Kurth T, Baune BT, Brinks R. Illness-Death Model as a Framework for Chronic Disease Burden Projection: Application to Mental Health Epidemiology. Front Epidemiol 2022; 2:903652. [PMID: 38455334 PMCID: PMC10910899 DOI: 10.3389/fepid.2022.903652] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/30/2022] [Indexed: 03/09/2024]
Abstract
Introduction Estimates of future disease burden supports public health decision-making. Multistate modeling of chronic diseases is still limited despite a long history of mathematical modeling of diseases. We introduce a discrete time approach to the illness-death model and a recursion formula, which can be utilized to project chronic disease burden. We further illustrate an example of the technique applied to anxiety disorders in Germany. Materials and Equipment The illness-death model is a multistate model that relates prevalence, incidence, mortality, and remission. A basic recursion formula that considers prevalence, incidence, mortality among the susceptible, and mortality among the diseased can be applied to irreversible chronic diseases such as diabetes. Among several mental disorders, remission plays a key role and thus an extended recursion formula taking remission into account is derived. Methods Using the Global Burden of Disease Study 2019 data and population projections from the Federal Statistical Office of Germany, a total number of individuals with anxiety disorders by sex in Germany from 2019 to 2030 was projected. Regression models were fitted to historical data for prevalence and incidence. Differential mortality risks were modeled based on empirical evidence. Remission was estimated from prevalence, incidence, and mortality, applying the extended recursion formula. Sex- and age-specific prevalence of 2019 was given as the initial value to estimate the total number of individuals with anxiety disorders for each year up to 2030. Projections were also made through simple extrapolation of prevalence for comparison. Results From 2019 to 2030, we estimated a decrease of 52,114 (-1.3%) individuals with anxiety disorders among women, and an increase of 166,870 (+8.5%) cases among men, through the illness-death model approach. With prevalence extrapolation, an increase of 381,770 (+9.7%) among women and an increase of 272,446 (+13.9%) among men were estimated. Discussion Application of the illness-death model with discrete time steps is possible for both irreversible chronic diseases and diseases with possible remissions, such as anxiety disorders. The technique provides a framework for disease burden prediction. The example provided here can form a basis for running simulations under varying transition probabilities.
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Affiliation(s)
- Chisato Ito
- Institute of Public Health, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Tobias Kurth
- Institute of Public Health, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Bernhard T. Baune
- Department of Psychiatry, University of Münster, Münster, Germany
- Department of Psychiatry, Melbourne Medical School, University of Melbourne, Melbourne, VIC, Australia
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Ralph Brinks
- Medical Biometry and Epidemiology, Faculty of Health, School of Medicine, Witten/Herdecke University, Witten, Germany
- Institute for Biometrics and Epidemiology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research, Heinrich Heine University, Düsseldorf, Germany
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15
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Abstract
Infectious disease modeling plays an important role in the response to infectious disease outbreaks, perhaps most notably during the coronavirus disease 2019 (COVID-19) pandemic. In our experience working with state and local governments during COVID-19 and previous public health crises, we have observed that, while the scientific literature focuses on models' accuracy and underlying assumptions, an important limitation on the effective application of modeling to public health decision-making is the ability of decision-makers and modelers to work together productively. We therefore propose a set of guiding principles, informed by our experience, for working relationships between decision-makers and modelers. We hypothesize that these guidelines will improve the utility of infectious disease modeling for public health decision-making, irrespective of the particular outbreak in question and of the precise modeling approaches being used.
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Affiliation(s)
- Scott W Olesen
- Center for Public Health Preparedness and Resilience, Institute for Public Research, CNA, Arlington, Virginia, USA
| | - Eric Trabert
- Center for Public Health Preparedness and Resilience, Institute for Public Research, CNA, Arlington, Virginia, USA
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16
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Manik S, Pal S, Mandal M, Hazra M. Effect of 2021 assembly election in India on COVID-19 transmission. Nonlinear Dyn 2022; 107:1343-1356. [PMID: 34803221 PMCID: PMC8590629 DOI: 10.1007/s11071-021-07041-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/29/2021] [Indexed: 05/21/2023]
Abstract
India is one of the countries in the world which is badly affected by the COVID-19 second wave. Assembly election in four states and a union territory of India was taken place during March-May 2021 when the COVID-19 second wave was close to its peak and affected a huge number of people. We studied the impact of assembly election on the effective contact rate and the effective reproduction number of COVID-19 using different epidemiological models like SIR, SIRD, and SEIR. We also modeled the effective reproduction number for all election-bound states using different mathematical functions. We separately studied the case of all election-bound states and found all the states showed a distinct increase in the effective contact rate and the effective reproduction number during the election-bound time and just after that compared to pre-election time. States, where elections were conducted in single-phase, showed less increase in the effective contact rate and the reproduction number. The election commission imposed extra measures from the first week of April 2021 to restrict big campaign rallies, meetings, and different political activities. The effective contact rate and the reproduction number showed a trend to decrease for few states due to the imposition of the restrictions. We also compared the effective contact rate, and the effective reproduction number of all election-bound states and the rest of India and found all the parameters related to the spread of virus for election-bound states are distinctly high compared to the rest of India.
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Affiliation(s)
- Souvik Manik
- Midnapore City College, Kuturia, Paschim Medinipur, 721129 India
| | - Sabyasachi Pal
- Midnapore City College, Kuturia, Paschim Medinipur, 721129 India
| | - Manoj Mandal
- Midnapore City College, Kuturia, Paschim Medinipur, 721129 India
| | - Mangal Hazra
- Midnapore City College, Kuturia, Paschim Medinipur, 721129 India
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17
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Borchering RK, Gunning CE, Gokhale DV, Weedop KB, Saeidpour A, Brett TS, Rohani P. Anomalous influenza seasonality in the United States and the emergence of novel influenza B viruses. Proc Natl Acad Sci U S A 2021; 118:e2012327118. [PMID: 33495348 DOI: 10.1073/pnas.2012327118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 2019/2020 influenza season in the United States began earlier than any season since the 2009 H1N1 pandemic, with an increase in influenza-like illnesses observed as early as August. Also noteworthy was the numerical domination of influenza B cases early in this influenza season, in contrast to their typically later peak in the past. Here, we dissect the 2019/2020 influenza season not only with regard to its unusually early activity, but also with regard to the relative dynamics of type A and type B cases. We propose that the recent expansion of a novel influenza B/Victoria clade may be associated with this shift in the composition and kinetics of the influenza season in the United States. We use epidemiological transmission models to explore whether changes in the effective reproduction number or short-term cross-immunity between these viruses can explain the dynamics of influenza A and B seasonality. We find support for an increase in the effective reproduction number of influenza B, rather than support for cross-type immunity-driven dynamics. Our findings have clear implications for optimal vaccination strategies.
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18
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Ubaida-Mohien C, Moaddel R, Moore AZ, Kuo PL, Faghri F, Tharakan R, Tanaka T, Nalls MA, Ferrucci L. Proteomics and Epidemiological Models of Human Aging. Front Physiol 2021; 12:674013. [PMID: 34135771 PMCID: PMC8202502 DOI: 10.3389/fphys.2021.674013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/03/2021] [Indexed: 12/21/2022] Open
Abstract
Human aging is associated with a decline of physical and cognitive function and high susceptibility to chronic diseases, which is influenced by genetics, epigenetics, environmental, and socio-economic status. In order to identify the factors that modulate the aging process, established measures of aging mechanisms are required, that are both robust and feasible in humans. It is also necessary to connect these measures to the phenotypes of aging and their functional consequences. In this review, we focus on how this has been addressed from an epidemiologic perspective using proteomics. The key aspects of epidemiological models of aging can be incorporated into proteomics and other omics which can provide critical detailed information on the molecular and biological processes that change with age, thus unveiling underlying mechanisms that drive multiple chronic conditions and frailty, and ideally facilitating the identification of new effective approaches for prevention and treatment.
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Affiliation(s)
- Ceereena Ubaida-Mohien
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Ruin Moaddel
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Ann Zenobia Moore
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Pei-Lun Kuo
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Faraz Faghri
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, United States.,Molecular Genetics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States.,Data Tecnica International, Glen Echo, MD, United States
| | - Ravi Tharakan
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Toshiko Tanaka
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
| | - Mike A Nalls
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, United States.,Molecular Genetics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States.,Data Tecnica International, Glen Echo, MD, United States
| | - Luigi Ferrucci
- Biomedical Research Center, National Institute on Aging, National Institute of Health, Baltimore, MD, United States
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19
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Bâldea I. Suppression of Groups Intermingling as an Appealing Option for Flattening and Delaying the Epidemiological Curve While Allowing Economic and Social Life at a Bearable Level during the COVID-19 Pandemic. Adv Theory Simul 2020; 3:2000132. [PMID: 33173845 PMCID: PMC7645871 DOI: 10.1002/adts.202000132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/07/2020] [Indexed: 11/23/2022]
Abstract
The COVID‐19 pandemic in a population modelled as a network wherein infection can propagate both via intra‐ and inter‐group interactions is simulated. The results emphasize the importance of diminishing the inter‐group infections in the effort of substantial flattening/delaying of the epi(demiologic) curve with concomitant mitigation of disastrous economy and social consequences. To exemplify, splitting a population into m (say, 5 or 10) noninteracting groups while keeping intra‐group interaction unchanged yields a stretched epidemiological curve having the maximum number of daily infections reduced and postponed in time by the same factor m (5 or 10). More generally, the study suggests a practical approach to fight against SARS‐ CoV‐ 2 virus spread based on population splitting into groups and minimizing intermingling between them. This strategy can be pursued by large‐scale infrastructure reorganization of activity at different levels in big logistic units (e.g., large productive networks, factories, enterprises, warehouses, schools, (seasonal) harvest work). Importantly, unlike total lockdown, the proposed approach prevents economic ruin and keeps social life at a more bearable level than distancing everyone from anyone. The declaration for the first time in Europe that COVID‐19 epidemic ended in the two‐million population Slovenia may be taken as support for the strategy proposed here.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie Universität Heidelberg INF 229 D‐69120 Heidelberg Germany
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20
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Soares ALO, Bassanezi RC. Stability analysis of epidemiological models incorporating heterogeneous infectivity. Comp. Appl. Math. 2020; 39:246. [PMCID: PMC7427276 DOI: 10.1007/s40314-020-01293-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 06/30/2020] [Accepted: 08/07/2020] [Indexed: 06/15/2023]
Abstract
In this paper we analyze general deterministic epidemiological models described by autonomous ordinary differential equations taking into account heterogeneity related to the infectivity and vital dynamics, in which the flow into the compartment of the susceptible individuals is given by a generic function. Our goal is to provide a new tool that facilitates the qualitative analysis of equilibrium points, which represent the disease free population, generalizing the result presented by Leite et al. (Math Med Biol J IMA 17:15–31, 2000) , and population extinction. The epidemiological models exposed are the type SEIRS (Susceptible-Exposed-Infectious-Recovered-Susceptible) and SEIR (Susceptible-Exposed-Infectious-Recovered) with vaccination. Moreover, we computed the basic reproduction number from the models by van den Driessche and Watmough (Math Biosci 180:29–48, 2002) and correlate this threshold parameter with the stability of the equilibrium point representing the disease free population.
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Affiliation(s)
- Anna Lígia Oenning Soares
- Departamento de Matemática, Universidade Federal de Mato Grosso, Av. Fernando Corrêa da Costa 2367, Cuiabá, 78060-900 Brazil
| | - Rodney Carlos Bassanezi
- Departamento de Matemática Aplicada, Universidade Estadual de Campinas, Rua Sérgio Buarque de Holanda 651, Campinas, 13083-859 Brazil
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21
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Roosa K, Luo R, Chowell G. Comparative assessment of parameter estimation methods in the presence of overdispersion: a simulation study. Math Biosci Eng 2019; 16:4299-4313. [PMID: 31499663 DOI: 10.3934/mbe.2019214] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Poisson distribution is commonly assumed as the error structure for count data; however, empirical data may exhibit greater variability than expected based on a given statistical model. Greater variability could point to model misspecification, such as missing crucial information about the epidemiology of the disease or changes in population behavior. When the mechanism producing the apparent overdispersion is unknown, it is typically assumed that the variance in the data exceeds the mean (by some scaling factor). Thus, a probability distribution that allows for overdispersion (negative binomial, for example) may better represent the data. Here, we utilize simulation studies to assess how misspecifying the error structure affects parameter estimation results, specifically bias and uncertainty, as a function of the level of random noise in the data. We compare results for two parameter estimation methods: nonlinear least squares and maximum likelihood estimation with Poisson error structure. We analyze two phenomenological models the generalized growth model and generalized logistic growth model to assess how results of parameter estimation are affected by the level of overdispersion underlying in the data. We use simulation to obtain confidence intervals and mean squared error of parameter estimates. We also analyze the impact of the amount of data, or ascending phase length, on the results of the generalized growth model for increasing levels of overdispersion. The results show a clear pattern of increasing uncertainty, or confidence interval width, as the overdispersion in the data increases. While maximum likelihood estimation consistently yields narrower confidence intervals and smaller mean squared error, differences between the two methods were minimal and not practically significant. At moderate levels of overdispersion, both estimation methods yielded similar performance. Importantly, it is shown that issues of parameter uncertainty and bias in the presence of overdispersion can be mitigated with the inclusion of more data.
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Affiliation(s)
- Kimberlyn Roosa
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, GA, USA
| | - Ruiyan Luo
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, GA, USA
| | - Gerardo Chowell
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, GA, USA
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institute of Health, Bethesda, MD, USA
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22
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Huijben S, Chan BHK, Nelson WA, Read AF. The impact of within-host ecology on the fitness of a drug-resistant parasite. Evol Med Public Health 2018; 2018:127-137. [PMID: 30087774 PMCID: PMC6061792 DOI: 10.1093/emph/eoy016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/18/2018] [Indexed: 02/05/2023]
Abstract
Background and objectives The rate of evolution of drug resistance depends on the fitness of resistant pathogens. The fitness of resistant pathogens is reduced by competition with sensitive pathogens in untreated hosts and so enhanced by competitive release in drug-treated hosts. We set out to estimate the magnitude of those effects on a variety of fitness measures, hypothesizing that competitive suppression and competitive release would have larger impacts when resistance was rarer to begin with. Methodology We infected mice with varying densities of drug-resistant Plasmodium chabaudi malaria parasites in a fixed density of drug-sensitive parasites and followed infection dynamics using strain-specific quantitative PCR. Results Competition with susceptible parasites reduced the absolute fitness of resistant parasites by 50–100%. Drug treatment increased the absolute fitness from 2- to >10 000-fold. The ecological context and choice of fitness measure was responsible for the wide variation in those estimates. Initial population growth rates poorly predicted parasite abundance and transmission probabilities. Conclusions and implications (i) The sensitivity of estimates of pathogen fitness to ecological context and choice of fitness measure make it difficult to derive field-relevant estimates of the fitness costs and benefits of resistance from experimental settings. (ii) Competitive suppression can be a key force preventing resistance from emerging when it is rare, as it is when it first arises. (iii) Drug treatment profoundly affects the fitness of resistance. Resistance evolution could be slowed by developing drug use policies that consider in-host competition.
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Affiliation(s)
- Silvie Huijben
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Brian H K Chan
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - William A Nelson
- Department of Biology, Queen's University, Kingston, ON K7L3N6, Canada
| | - Andrew F Read
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA.,Department of Fogarty, National Institutes of Health, Fogarty International Center, Bethesda, MD, USA
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23
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Drawert B, Griesemer M, Petzold LR, Briggs CJ. Using stochastic epidemiological models to evaluate conservation strategies for endangered amphibians. J R Soc Interface 2018; 14:rsif.2017.0480. [PMID: 28855388 PMCID: PMC5582134 DOI: 10.1098/rsif.2017.0480] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 08/07/2017] [Indexed: 01/02/2023] Open
Abstract
Recent outbreaks of chytridiomycosis, the disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have contributed to population declines of numerous amphibian species worldwide. The devastating impacts of this disease have led researchers to attempt drastic conservation measures to prevent further extinctions and loss of biodiversity. The conservation measures can be labour-intensive or expensive, and in many cases have been unsuccessful. We developed a mathematical model of Bd outbreaks that includes the effects of demographic stochasticity and within-host fungal load dynamics. We investigated the impacts of one-time treatment conservation strategies during the disease outbreak that occurs following the initial arrival of Bd into a previously uninfected frog population. We found that for all versions of the model, for a large fraction of parameter space, none of the one-time treatment strategies are effective at preventing disease-induced extinction of the amphibian population. Of the strategies considered, treating frogs with antifungal agents to reduce their fungal load had the greatest likelihood of a beneficial outcome and the lowest risk of decreasing the persistence of the frog population, suggesting that this disease mitigation strategy should be prioritized over disinfecting the environment or reducing host density.
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Affiliation(s)
- Brian Drawert
- Department of Computer Science, University of North Carolina Asheville, Asheville, NC 28804, USA
| | - Marc Griesemer
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
| | - Linda R Petzold
- Department of Computer Science, University of California, Santa Barbara, CA 93106, USA
| | - Cheryl J Briggs
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA
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24
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Arregui S, Iglesias MJ, Samper S, Marinova D, Martin C, Sanz J, Moreno Y. Data-driven model for the assessment of Mycobacterium tuberculosis transmission in evolving demographic structures. Proc Natl Acad Sci U S A 2018; 115:E3238-E3245. [PMID: 29563223 PMCID: PMC5889657 DOI: 10.1073/pnas.1720606115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In the case of tuberculosis (TB), the capabilities of epidemic models to produce quantitatively robust forecasts are limited by multiple hindrances. Among these, understanding the complex relationship between disease epidemiology and populations' age structure has been highlighted as one of the most relevant. TB dynamics depends on age in multiple ways, some of which are traditionally simplified in the literature. That is the case of the heterogeneities in contact intensity among different age strata that are common to all airborne diseases, but still typically neglected in the TB case. Furthermore, while demographic structures of many countries are rapidly aging, demographic dynamics are pervasively ignored when modeling TB spreading. In this work, we present a TB transmission model that incorporates country-specific demographic prospects and empirical contact data around a data-driven description of TB dynamics. Using our model, we find that the inclusion of demographic dynamics is followed by an increase in the burden levels predicted for the next decades in the areas of the world that are most hit by the disease today. Similarly, we show that considering realistic patterns of contacts among individuals in different age strata reshapes the transmission patterns reproduced by the models, a result with potential implications for the design of age-focused epidemiological interventions.
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Affiliation(s)
- Sergio Arregui
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, 50018 Zaragoza, Spain;
- Department of Theoretical Physics, University of Zaragoza, 50009 Zaragoza, Spain
| | - María José Iglesias
- Department of Microbiology, Faculty of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en red Enfermedades Respiratorias (CIBER), Carlos III Health Institute, 28029 Madrid, Spain
| | - Sofía Samper
- Centro de Investigación Biomédica en red Enfermedades Respiratorias (CIBER), Carlos III Health Institute, 28029 Madrid, Spain
- Instituto Aragonés de Ciencias de la Salud, Instituto de Investigación Sanitaria (IIS) Aragon, 50009 Zaragoza, Spain
| | - Dessislava Marinova
- Department of Microbiology, Faculty of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en red Enfermedades Respiratorias (CIBER), Carlos III Health Institute, 28029 Madrid, Spain
| | - Carlos Martin
- Department of Microbiology, Faculty of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en red Enfermedades Respiratorias (CIBER), Carlos III Health Institute, 28029 Madrid, Spain
- Service of Microbiology, Miguel Servet Hospital, Instituto de Investigación Sanitaria (IIS) Aragon, 50009 Zaragoza, Spain
| | - Joaquín Sanz
- Department of Genetics, Sainte-Justine Hospital Research Centre, Montreal, QC H3T1C5, Canada
- Department of Biochemistry, Faculty of Medicine, University of Montreal, Montreal, QC H3T1J4, Canada
| | - Yamir Moreno
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, 50018 Zaragoza, Spain;
- Department of Theoretical Physics, University of Zaragoza, 50009 Zaragoza, Spain
- Institute for Scientific Interchange, ISI Foundation, 10126 Turin, Italy
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25
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Biek R, Pybus OG, Lloyd-Smith JO, Didelot X. Measurably evolving pathogens in the genomic era. Trends Ecol Evol 2015; 30:306-13. [PMID: 25887947 DOI: 10.1016/j.tree.2015.03.009] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/06/2015] [Accepted: 03/11/2015] [Indexed: 01/26/2023]
Abstract
Current sequencing technologies have created unprecedented opportunities for studying microbial populations. For pathogens with comparatively low per-site mutation rates, such as DNA viruses and bacteria, whole-genome sequencing can reveal the accumulation of novel genetic variation between population samples taken at different times. The concept of 'measurably evolving populations' and related analytical approaches have provided powerful insights for fast-evolving RNA viruses, but their application to other pathogens is still in its infancy. We argue that previous distinctions between slow- and fast-evolving pathogens become blurred once evolution is assessed at a genome-wide scale, and we highlight important analytical challenges to be overcome to infer pathogen population dynamics from genomic data.
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Affiliation(s)
- Roman Biek
- Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK; Fogarty International Center, National Institutes of Health, Bethesda MD, USA.
| | | | - James O Lloyd-Smith
- Fogarty International Center, National Institutes of Health, Bethesda MD, USA; Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College, London, UK
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Schang L, De Poli C, Airoldi M, Morton A, Bohm N, Lakhanpaul M, Schilder A, Bevan G. Using an epidemiological model to investigate unwarranted variation: the case of ventilation tubes for otitis media with effusion in England. J Health Serv Res Policy 2014; 19:236-44. [PMID: 25074279 DOI: 10.1177/1355819614536886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES To investigate unwarranted variation in ventilation tube insertions for otitis media with effusion in children in England. This procedure is known to be 'overused' from clinical audits, as only one in three ventilation tube insertions conforms to the appropriateness criteria of the National Institute for Health and Care Excellence (NICE); but audits cannot identify the scale of 'underuse' - i.e. patients who would benefit but are not treated. METHODS To explore both 'underuse' and 'overuse' of ventilation tubes for otitis media with effusion, we developed an epidemiological model based on: definitions of children with otitis media with effusion expected to benefit from ventilation tubes according to NICE guidance; epidemiological and clinical information from a systematic review; and expert judgement. A range of estimates was derived using Monte Carlo simulation and compared with the number of ventilation tubes provided in the English National Health Service in 2010. RESULTS About 32,200 children in England would be expected to benefit from ventilation tubes for otitis media with effusion per year (between 20,411 and 45,231 with 90% certainty). The observed number of ventilation tubes for otitis media with effusion-associated diagnoses was 16,824. CONCLUSIONS The expected population capacity to benefit from ventilation tubes for otitis media with effusion based on NICE guidance appeared to exceed, by far, the number of ventilation tubes provided in the English National Health Service. So, while there is known 'overuse', there also may be substantial 'underuse' of ventilation tubes for otitis media with effusion if NICE criteria were applied. Future investigations of unwarranted variation should, therefore, not only focus on the patients who are treated but also consider the potential for benefit at the population level.
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Affiliation(s)
- Laura Schang
- Doctoral Student, Department of Management, London School of Economics and Political Science, England, UK
| | - Chiara De Poli
- Research Assistant, Department of Management, London School of Economics and Political Science, England, UK
| | - Mara Airoldi
- Fellow, Department of Management, London School of Economics and Political Science, England, UK
| | - Alec Morton
- Professor of Management Science, Department of Management Science, Strathclyde Business School, University of Strathclyde, Scotland, UK
| | - Natalie Bohm
- Clinical Academic Lecturer, Ear Institute, University College London, England, UK
| | - Monica Lakhanpaul
- Professor of Integrated Community Child Health, General and Adolescent Paediatrics Unit, UCL Institute of Child Health, England, UK
| | - Anne Schilder
- NIHR Research Professor and Professor of Paediatric Otorhinolaryngology, Ear Institute, University College London, England, UK
| | - Gwyn Bevan
- Professor of Policy Analysis, Department of Management, London School of Economics and Political Science, England, UK
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Pérez-Reche FJ, Neri FM, Taraskin SN, Gilligan CA. Prediction of invasion from the early stage of an epidemic. J R Soc Interface 2012; 9:2085-96. [PMID: 22513723 PMCID: PMC3405761 DOI: 10.1098/rsif.2012.0130] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 03/23/2012] [Indexed: 12/22/2022] Open
Abstract
Predictability of undesired events is a question of great interest in many scientific disciplines including seismology, economy and epidemiology. Here, we focus on the predictability of invasion of a broad class of epidemics caused by diseases that lead to permanent immunity of infected hosts after recovery or death. We approach the problem from the perspective of the science of complexity by proposing and testing several strategies for the estimation of important characteristics of epidemics, such as the probability of invasion. Our results suggest that parsimonious approximate methodologies may lead to the most reliable and robust predictions. The proposed methodologies are first applied to analysis of experimentally observed epidemics: invasion of the fungal plant pathogen Rhizoctonia solani in replicated host microcosms. We then consider numerical experiments of the susceptible-infected-removed model to investigate the performance of the proposed methods in further detail. The suggested framework can be used as a valuable tool for quick assessment of epidemic threat at the stage when epidemics only start developing. Moreover, our work amplifies the significance of the small-scale and finite-time microcosm realizations of epidemics revealing their predictive power.
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Abstract
The study uses time-series modelling to determine and predict trends in incident HIV infection in Ghana among specific age groups. The HIV data for Ghana were grouped according to northern and southern spatial sectors as they exhibited slightly different data collection formats. The trend of the epidemic is modelled using moving-average smoothing techniques, and the Box-Jenkins ARIMA model is used to forecast cases of newly acquired (incident) HIV infection. Trend analysis of past growth patterns reveals an increase in new cases of HIV infection in the northern sector, with the greatest increase occurring among persons aged 30 years and over. The epidemic in the southern sector appears to have levelled off. However, incident HIV infection in the 20-39-year-old age group of females in the sector is estimated to increase in the next three years. Moreover, the estimates suggest a higher increase in incident cases than that predicted by the National AIDS Control Programme. Nevertheless, incident HIV infection among persons aged 19 and below is found to be relatively stable. Thus, if efforts are made to reduce or prevent an increase in the number of new infections in the northern sector, and for the 20-39 years age group in the southern sector, Ghana will have a brighter future with regard to its response to the HIV epidemic. These findings can assist with developing strategic-intervention policy planning for Ghana and other countries in sub-Saharan Africa.
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Affiliation(s)
- Patrick Aboagye-Sarfo
- a School of Engineering , Edith Cowan University , 100 Joondalup Drive, Joondalup , Western Australia , 6027 , Australia E-mail:
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Abstract
▪ Abstract Research on impacts of climate change on plant diseases has been limited, with most work concentrating on the effects of a single atmospheric constituent or meteorological variable on the host, pathogen, or the interaction of the two under controlled conditions. Results indicate that climate change could alter stages and rates of development of the pathogen, modify host resistance, and result in changes in the physiology of host-pathogen interactions. The most likely consequences are shifts in the geographical distribution of host and pathogen and altered crop losses, caused in part by changes in the efficacy of control strategies. Recent developments in experimental and modeling techniques offer considerable promise for developing an improved capability for climate change impact assessment and mitigation. Compared with major technological, environmental, and socioeconomic changes affecting agricultural production during the next century, climate change may be less important; it will, however, add another layer of complexity and uncertainty onto a system that is already exceedingly difficult to manage on a sustainable basis. Intensified research on climate change-related issues could result in improved understanding and management of plant diseases in the face of current and future climate extremes.
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Affiliation(s)
- S M Coakley
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331; e-mail:
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