Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study.
<h4>Background</h4>The ongoing West African Ebola epidemic began in December 2013 in Guinea, probably from a single zoonotic introduction. As a result of ineffective initial control efforts, an Ebola outbreak of unprecedented scale emerged. As of 4 May 2015, it had resulted in more than...
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2016-11-01
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| Online Access: | https://doi.org/10.1371/journal.pmed.1002170 |
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| author | International Ebola Response Team Junerlyn Agua-Agum Archchun Ariyarajah Bruce Aylward Luke Bawo Pepe Bilivogui Isobel M Blake Richard J Brennan Amy Cawthorne Eilish Cleary Peter Clement Roland Conteh Anne Cori Foday Dafae Benjamin Dahl Jean-Marie Dangou Boubacar Diallo Christl A Donnelly Ilaria Dorigatti Christopher Dye Tim Eckmanns Mosoka Fallah Neil M Ferguson Lena Fiebig Christophe Fraser Tini Garske Lice Gonzalez Esther Hamblion Nuha Hamid Sara Hersey Wes Hinsley Amara Jambei Thibaut Jombart David Kargbo Sakoba Keita Michael Kinzer Fred Kuti George Beatrice Godefroy Giovanna Gutierrez Niluka Kannangarage Harriet L Mills Thomas Moller Sascha Meijers Yasmine Mohamed Oliver Morgan Gemma Nedjati-Gilani Emily Newton Pierre Nouvellet Tolbert Nyenswah William Perea Devin Perkins Steven Riley Guenael Rodier Marc Rondy Maria Sagrado Camelia Savulescu Ilana J Schafer Dirk Schumacher Thomas Seyler Anita Shah Maria D Van Kerkhove C Samford Wesseh Zabulon Yoti |
| author_facet | International Ebola Response Team Junerlyn Agua-Agum Archchun Ariyarajah Bruce Aylward Luke Bawo Pepe Bilivogui Isobel M Blake Richard J Brennan Amy Cawthorne Eilish Cleary Peter Clement Roland Conteh Anne Cori Foday Dafae Benjamin Dahl Jean-Marie Dangou Boubacar Diallo Christl A Donnelly Ilaria Dorigatti Christopher Dye Tim Eckmanns Mosoka Fallah Neil M Ferguson Lena Fiebig Christophe Fraser Tini Garske Lice Gonzalez Esther Hamblion Nuha Hamid Sara Hersey Wes Hinsley Amara Jambei Thibaut Jombart David Kargbo Sakoba Keita Michael Kinzer Fred Kuti George Beatrice Godefroy Giovanna Gutierrez Niluka Kannangarage Harriet L Mills Thomas Moller Sascha Meijers Yasmine Mohamed Oliver Morgan Gemma Nedjati-Gilani Emily Newton Pierre Nouvellet Tolbert Nyenswah William Perea Devin Perkins Steven Riley Guenael Rodier Marc Rondy Maria Sagrado Camelia Savulescu Ilana J Schafer Dirk Schumacher Thomas Seyler Anita Shah Maria D Van Kerkhove C Samford Wesseh Zabulon Yoti |
| author_sort | International Ebola Response Team |
| collection | DOAJ |
| description | <h4>Background</h4>The ongoing West African Ebola epidemic began in December 2013 in Guinea, probably from a single zoonotic introduction. As a result of ineffective initial control efforts, an Ebola outbreak of unprecedented scale emerged. As of 4 May 2015, it had resulted in more than 19,000 probable and confirmed Ebola cases, mainly in Guinea (3,529), Liberia (5,343), and Sierra Leone (10,746). Here, we present analyses of data collected during the outbreak identifying drivers of transmission and highlighting areas where control could be improved.<h4>Methods and findings</h4>Over 19,000 confirmed and probable Ebola cases were reported in West Africa by 4 May 2015. Individuals with confirmed or probable Ebola ("cases") were asked if they had exposure to other potential Ebola cases ("potential source contacts") in a funeral or non-funeral context prior to becoming ill. We performed retrospective analyses of a case line-list, collated from national databases of case investigation forms that have been reported to WHO. These analyses were initially performed to assist WHO's response during the epidemic, and have been updated for publication. We analysed data from 3,529 cases in Guinea, 5,343 in Liberia, and 10,746 in Sierra Leone; exposures were reported by 33% of cases. The proportion of cases reporting a funeral exposure decreased over time. We found a positive correlation (r = 0.35, p < 0.001) between this proportion in a given district for a given month and the within-district transmission intensity, quantified by the estimated reproduction number (R). We also found a negative correlation (r = -0.37, p < 0.001) between R and the district proportion of hospitalised cases admitted within ≤4 days of symptom onset. These two proportions were not correlated, suggesting that reduced funeral attendance and faster hospitalisation independently influenced local transmission intensity. We were able to identify 14% of potential source contacts as cases in the case line-list. Linking cases to the contacts who potentially infected them provided information on the transmission network. This revealed a high degree of heterogeneity in inferred transmissions, with only 20% of cases accounting for at least 73% of new infections, a phenomenon often called super-spreading. Multivariable regression models allowed us to identify predictors of being named as a potential source contact. These were similar for funeral and non-funeral contacts: severe symptoms, death, non-hospitalisation, older age, and travelling prior to symptom onset. Non-funeral exposures were strongly peaked around the death of the contact. There was evidence that hospitalisation reduced but did not eliminate onward exposures. We found that Ebola treatment units were better than other health care facilities at preventing exposure from hospitalised and deceased individuals. The principal limitation of our analysis is limited data quality, with cases not being entered into the database, cases not reporting exposures, or data being entered incorrectly (especially dates, and possible misclassifications).<h4>Conclusions</h4>Achieving elimination of Ebola is challenging, partly because of super-spreading. Safe funeral practices and fast hospitalisation contributed to the containment of this Ebola epidemic. Continued real-time data capture, reporting, and analysis are vital to track transmission patterns, inform resource deployment, and thus hasten and maintain elimination of the virus from the human population. |
| format | Article |
| id | doaj-art-4560623d69a04654a3c5ec1e77a63f4c |
| institution | OA Journals |
| issn | 1549-1277 1549-1676 |
| language | English |
| publishDate | 2016-11-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Medicine |
| spelling | doaj-art-4560623d69a04654a3c5ec1e77a63f4c2025-08-20T02:31:41ZengPublic Library of Science (PLoS)PLoS Medicine1549-12771549-16762016-11-011311e100217010.1371/journal.pmed.1002170Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study.International Ebola Response TeamJunerlyn Agua-AgumArchchun AriyarajahBruce AylwardLuke BawoPepe BilivoguiIsobel M BlakeRichard J BrennanAmy CawthorneEilish ClearyPeter ClementRoland ContehAnne CoriFoday DafaeBenjamin DahlJean-Marie DangouBoubacar DialloChristl A DonnellyIlaria DorigattiChristopher DyeTim EckmannsMosoka FallahNeil M FergusonLena FiebigChristophe FraserTini GarskeLice GonzalezEsther HamblionNuha HamidSara HerseyWes HinsleyAmara JambeiThibaut JombartDavid KargboSakoba KeitaMichael KinzerFred Kuti GeorgeBeatrice GodefroyGiovanna GutierrezNiluka KannangarageHarriet L MillsThomas MollerSascha MeijersYasmine MohamedOliver MorganGemma Nedjati-GilaniEmily NewtonPierre NouvelletTolbert NyenswahWilliam PereaDevin PerkinsSteven RileyGuenael RodierMarc RondyMaria SagradoCamelia SavulescuIlana J SchaferDirk SchumacherThomas SeylerAnita ShahMaria D Van KerkhoveC Samford WessehZabulon Yoti<h4>Background</h4>The ongoing West African Ebola epidemic began in December 2013 in Guinea, probably from a single zoonotic introduction. As a result of ineffective initial control efforts, an Ebola outbreak of unprecedented scale emerged. As of 4 May 2015, it had resulted in more than 19,000 probable and confirmed Ebola cases, mainly in Guinea (3,529), Liberia (5,343), and Sierra Leone (10,746). Here, we present analyses of data collected during the outbreak identifying drivers of transmission and highlighting areas where control could be improved.<h4>Methods and findings</h4>Over 19,000 confirmed and probable Ebola cases were reported in West Africa by 4 May 2015. Individuals with confirmed or probable Ebola ("cases") were asked if they had exposure to other potential Ebola cases ("potential source contacts") in a funeral or non-funeral context prior to becoming ill. We performed retrospective analyses of a case line-list, collated from national databases of case investigation forms that have been reported to WHO. These analyses were initially performed to assist WHO's response during the epidemic, and have been updated for publication. We analysed data from 3,529 cases in Guinea, 5,343 in Liberia, and 10,746 in Sierra Leone; exposures were reported by 33% of cases. The proportion of cases reporting a funeral exposure decreased over time. We found a positive correlation (r = 0.35, p < 0.001) between this proportion in a given district for a given month and the within-district transmission intensity, quantified by the estimated reproduction number (R). We also found a negative correlation (r = -0.37, p < 0.001) between R and the district proportion of hospitalised cases admitted within ≤4 days of symptom onset. These two proportions were not correlated, suggesting that reduced funeral attendance and faster hospitalisation independently influenced local transmission intensity. We were able to identify 14% of potential source contacts as cases in the case line-list. Linking cases to the contacts who potentially infected them provided information on the transmission network. This revealed a high degree of heterogeneity in inferred transmissions, with only 20% of cases accounting for at least 73% of new infections, a phenomenon often called super-spreading. Multivariable regression models allowed us to identify predictors of being named as a potential source contact. These were similar for funeral and non-funeral contacts: severe symptoms, death, non-hospitalisation, older age, and travelling prior to symptom onset. Non-funeral exposures were strongly peaked around the death of the contact. There was evidence that hospitalisation reduced but did not eliminate onward exposures. We found that Ebola treatment units were better than other health care facilities at preventing exposure from hospitalised and deceased individuals. The principal limitation of our analysis is limited data quality, with cases not being entered into the database, cases not reporting exposures, or data being entered incorrectly (especially dates, and possible misclassifications).<h4>Conclusions</h4>Achieving elimination of Ebola is challenging, partly because of super-spreading. Safe funeral practices and fast hospitalisation contributed to the containment of this Ebola epidemic. Continued real-time data capture, reporting, and analysis are vital to track transmission patterns, inform resource deployment, and thus hasten and maintain elimination of the virus from the human population.https://doi.org/10.1371/journal.pmed.1002170 |
| spellingShingle | International Ebola Response Team Junerlyn Agua-Agum Archchun Ariyarajah Bruce Aylward Luke Bawo Pepe Bilivogui Isobel M Blake Richard J Brennan Amy Cawthorne Eilish Cleary Peter Clement Roland Conteh Anne Cori Foday Dafae Benjamin Dahl Jean-Marie Dangou Boubacar Diallo Christl A Donnelly Ilaria Dorigatti Christopher Dye Tim Eckmanns Mosoka Fallah Neil M Ferguson Lena Fiebig Christophe Fraser Tini Garske Lice Gonzalez Esther Hamblion Nuha Hamid Sara Hersey Wes Hinsley Amara Jambei Thibaut Jombart David Kargbo Sakoba Keita Michael Kinzer Fred Kuti George Beatrice Godefroy Giovanna Gutierrez Niluka Kannangarage Harriet L Mills Thomas Moller Sascha Meijers Yasmine Mohamed Oliver Morgan Gemma Nedjati-Gilani Emily Newton Pierre Nouvellet Tolbert Nyenswah William Perea Devin Perkins Steven Riley Guenael Rodier Marc Rondy Maria Sagrado Camelia Savulescu Ilana J Schafer Dirk Schumacher Thomas Seyler Anita Shah Maria D Van Kerkhove C Samford Wesseh Zabulon Yoti Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. PLoS Medicine |
| title | Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. |
| title_full | Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. |
| title_fullStr | Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. |
| title_full_unstemmed | Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. |
| title_short | Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study. |
| title_sort | exposure patterns driving ebola transmission in west africa a retrospective observational study |
| url | https://doi.org/10.1371/journal.pmed.1002170 |
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