title: Early epidemic dynamics of the west african 2014 ebola outbreak: estimates derived with a simple two-parameter model.
abstract: The 2014 West African Ebola virus outbreak, now more correctly referred to as an epidemic, is the largest ever to occur. As of August 28, 2014, concerns have been raised that control efforts, particularly in Liberia, have been ineffective, as reported case counts continue to increase. Limited data are available on the epidemiology of the outbreak. However, reported cumulative incidence data as well as death counts are available for Guinea, Sierra Leone, Liberia and Nigeria. We utilized a simple, two parameter mathematical model of epidemic growth and control, to characterize epidemic growth patterns in West Africa, to evaluate the degree to which the epidemic is being controlled, and to assess the potential implications of growth patterns for epidemic size. Models demonstrated good fits to data. Overall basic reproductive number (R0) for the epidemic was estimated to be between 1.6 and 2.0, consistent with prior outbreaks. However, we identified only weak evidence for the occurrence of epidemic control in West Africa as a whole, and essentially no evidence for control in Liberia (though slowing of growth was seen in Guinea and Sierra Leone). It is projected that small reductions in transmission would prevent tens of thousands of future infections. These findings suggest that there is an extraordinary need for improved control measures for the 2014 Ebola epidemic, especially in Liberia, if catastrophe is to be averted.
authors: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors: David
authors: D
authors: Fisman
authors: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors: Edwin
authors: E
authors: Khoo
authors: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors: Ashleigh
authors: A
authors: Tuite
references: Value Health. 2012 Sep-Oct;15(6):828-34
references: 22999132
references: PLoS One. 2013 Dec 31;8(12):e83622
references: 24391797
references: Osong Public Health Res Perspect. 2011 Jun;2(1):3-7
references: 24159443
references: CMAJ. 2009 Aug 4;181(3-4):171-3
references: 19620267
references: Epidemiol Infect. 2007 May;135(4):610-21
references: 16999875
references: MMWR Morb Mortal Wkly Rep. 2014 Jun 27;63(25):548-51
references: 24964881
references: J Infect Dis. 2011 Nov;204 Suppl 3:S810-6
references: 21987756
references: N Engl J Med. 2014 Sep 25;371(13):1180-3
references: 25140855
references: J Theor Biol. 2004 Jul 7;229(1):119-26
references: 15178190