CITATION: Exposure Patterns Driving Ebola Transmission in West Africa: A Retrospective Observational Study

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,  [ … ], Zabulon Yoti [ view all ]

Published: November 15, 2016


Why Was This Study Done? 

Knowing how and from whom individuals acquire infection can help inform the response to limit the impact of an epidemic; this study presents updated versions of analyses initially performed to assist the international response during the 2013–2016 Ebola epidemic in West Africa. Over 19,000 individuals with confirmed or probable Ebola (“cases”) were reported in West Africa by 4 May 2015. Cases were asked whether they had exposure to potential Ebola cases (“potential source contacts”) in a funeral or non-funeral context prior to becoming ill.

What Did the Researchers Do and Find? 

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. Non-funeral exposures were strongly peaked around the time of death of the contact. There was evidence of super-spreading, with only 20% of cases accounting for at least 73% of new infections.

What Do These Findings Mean? 

Safe funeral practices and fast hospitalisation contributed to the containment of this Ebola epidemic.

The data are highly detailed despite the challenging circumstances in the three countries; however, the analyses were limited by data quality, mostly missing data and incorrect entries. In light of viral persistence in reservoirs, it is vital to maintain active surveillance and analysis of Ebola outbreaks to avoid and contain future outbreaks.

Best wishes, Neil

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