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A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks

BACKGROUND: Outbreaks of poliomyelitis in African countries that were previously free of wild-type poliovirus cost the Global Polio Eradication Initiative US$850 million during 2003–2009, and have limited the ability of the program to focus on endemic countries. A quantitative understanding of the f...

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Autores principales: O'Reilly, Kathleen M., Chauvin, Claire, Aylward, R. Bruce, Maher, Chris, Okiror, Sam, Wolff, Chris, Nshmirimana, Deo, Donnelly, Christl A., Grassly, Nicholas C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3196484/
https://www.ncbi.nlm.nih.gov/pubmed/22028632
http://dx.doi.org/10.1371/journal.pmed.1001109
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author O'Reilly, Kathleen M.
Chauvin, Claire
Aylward, R. Bruce
Maher, Chris
Okiror, Sam
Wolff, Chris
Nshmirimana, Deo
Donnelly, Christl A.
Grassly, Nicholas C.
author_facet O'Reilly, Kathleen M.
Chauvin, Claire
Aylward, R. Bruce
Maher, Chris
Okiror, Sam
Wolff, Chris
Nshmirimana, Deo
Donnelly, Christl A.
Grassly, Nicholas C.
author_sort O'Reilly, Kathleen M.
collection PubMed
description BACKGROUND: Outbreaks of poliomyelitis in African countries that were previously free of wild-type poliovirus cost the Global Polio Eradication Initiative US$850 million during 2003–2009, and have limited the ability of the program to focus on endemic countries. A quantitative understanding of the factors that predict the distribution and timing of outbreaks will enable their prevention and facilitate the completion of global eradication. METHODS AND FINDINGS: Children with poliomyelitis in Africa from 1 January 2003 to 31 December 2010 were identified through routine surveillance of cases of acute flaccid paralysis, and separate outbreaks associated with importation of wild-type poliovirus were defined using the genetic relatedness of these viruses in the VP1/2A region. Potential explanatory variables were examined for their association with the number, size, and duration of poliomyelitis outbreaks in 6-mo periods using multivariable regression analysis. The predictive ability of 6-mo-ahead forecasts of poliomyelitis outbreaks in each country based on the regression model was assessed. A total of 142 genetically distinct outbreaks of poliomyelitis were recorded in 25 African countries, resulting in 1–228 cases (median of two cases). The estimated number of people arriving from infected countries and <5-y childhood mortality were independently associated with the number of outbreaks. Immunisation coverage based on the reported vaccination history of children with non-polio acute flaccid paralysis was associated with the duration and size of each outbreak, as well as the number of outbreaks. Six-month-ahead forecasts of the number of outbreaks in a country or region changed over time and had a predictive ability of 82%. CONCLUSIONS: Outbreaks of poliomyelitis resulted primarily from continued transmission in Nigeria and the poor immunisation status of populations in neighbouring countries. From 1 January 2010 to 30 June 2011, reduced transmission in Nigeria and increased incidence in reinfected countries in west and central Africa have changed the geographical risk of polio outbreaks, and will require careful immunisation planning to limit onward spread. Please see later in the article for the Editors' Summary
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spelling pubmed-31964842011-10-25 A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks O'Reilly, Kathleen M. Chauvin, Claire Aylward, R. Bruce Maher, Chris Okiror, Sam Wolff, Chris Nshmirimana, Deo Donnelly, Christl A. Grassly, Nicholas C. PLoS Med Research Article BACKGROUND: Outbreaks of poliomyelitis in African countries that were previously free of wild-type poliovirus cost the Global Polio Eradication Initiative US$850 million during 2003–2009, and have limited the ability of the program to focus on endemic countries. A quantitative understanding of the factors that predict the distribution and timing of outbreaks will enable their prevention and facilitate the completion of global eradication. METHODS AND FINDINGS: Children with poliomyelitis in Africa from 1 January 2003 to 31 December 2010 were identified through routine surveillance of cases of acute flaccid paralysis, and separate outbreaks associated with importation of wild-type poliovirus were defined using the genetic relatedness of these viruses in the VP1/2A region. Potential explanatory variables were examined for their association with the number, size, and duration of poliomyelitis outbreaks in 6-mo periods using multivariable regression analysis. The predictive ability of 6-mo-ahead forecasts of poliomyelitis outbreaks in each country based on the regression model was assessed. A total of 142 genetically distinct outbreaks of poliomyelitis were recorded in 25 African countries, resulting in 1–228 cases (median of two cases). The estimated number of people arriving from infected countries and <5-y childhood mortality were independently associated with the number of outbreaks. Immunisation coverage based on the reported vaccination history of children with non-polio acute flaccid paralysis was associated with the duration and size of each outbreak, as well as the number of outbreaks. Six-month-ahead forecasts of the number of outbreaks in a country or region changed over time and had a predictive ability of 82%. CONCLUSIONS: Outbreaks of poliomyelitis resulted primarily from continued transmission in Nigeria and the poor immunisation status of populations in neighbouring countries. From 1 January 2010 to 30 June 2011, reduced transmission in Nigeria and increased incidence in reinfected countries in west and central Africa have changed the geographical risk of polio outbreaks, and will require careful immunisation planning to limit onward spread. Please see later in the article for the Editors' Summary Public Library of Science 2011-10-18 /pmc/articles/PMC3196484/ /pubmed/22028632 http://dx.doi.org/10.1371/journal.pmed.1001109 Text en O'Reilly et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
O'Reilly, Kathleen M.
Chauvin, Claire
Aylward, R. Bruce
Maher, Chris
Okiror, Sam
Wolff, Chris
Nshmirimana, Deo
Donnelly, Christl A.
Grassly, Nicholas C.
A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title_full A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title_fullStr A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title_full_unstemmed A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title_short A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks
title_sort statistical model of the international spread of wild poliovirus in africa used to predict and prevent outbreaks
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3196484/
https://www.ncbi.nlm.nih.gov/pubmed/22028632
http://dx.doi.org/10.1371/journal.pmed.1001109
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