TY - JOUR AB - BACKGROUND: 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.METHODS AND FINDINGS: 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 AU - International,Ebola Response Team AU - Agua-Agum,J AU - Ariyarajah,A AU - Aylward,B AU - Bawo,L AU - Bilivogui,P AU - Blake,IM AU - Brennan,RJ AU - Cawthorne,A AU - Cleary,E AU - Clement,P AU - Conteh,R AU - Cori,A AU - Dafae,F AU - Dahl,B AU - Dangou,JM AU - Diallo,B AU - Donnelly,CA AU - Dorigatti,I AU - Dye,C AU - Eckmanns,T AU - Fallah,M AU - Ferguson,NM AU - Fiebig,L AU - Fraser,C AU - Garske,T AU - Gonzalez,L AU - Hamblion,E AU - Hamid,N AU - Hersey,S AU - Hinsley,W AU - Jambei,A AU - Jombart,T AU - Kargbo,D AU - Keita,S AU - Kinzer,M AU - George,FK AU - Godefroy,B AU - Gutierrez,G AU - Kannangarage,N AU - Mills,HL AU - Moller,T AU - Meijers,S AU - Mohamed,Y AU - Morgan,O AU - Nedjati-Gilani,G AU - Newton,E AU - Nouvellet,P AU - Nyenswah,T AU - Perea,W AU - Perkins,D AU - Riley,S AU - Rodier,G AU - Rondy,M AU - Sagrado,M AU - Savulescu,C AU - Schafer,IJ AU - Schumacher,D AU - Seyler,T AU - Shah,A AU - Van,Kerkhove MD AU - Wesseh,CS AU - Yoti,Z DO - 10.1371/journal.pmed.1002170 PY - 2016/// SN - 1549-1277 TI - Exposure patterns driving Ebola transmissions in West Africa: a retrospective observational study T2 - PLOS Medicine UR - http://dx.doi.org/10.1371/journal.pmed.1002170 UR - http://www.ncbi.nlm.nih.gov/pubmed/27846234 UR - http://hdl.handle.net/10044/1/42949 VL - 13 ER -