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. 2016 May;144(7):1473-81.
doi: 10.1017/S0950268815003003.

Assessment of the severity of Ebola virus disease in Sierra Leone in 2014-2015

J Y Wong  1 , W Zhang  2 , D Kargbo  3 , U Haque  4 , W Hu  5 , P Wu  1 , A Kamara  3 , Y Chen  2 , B Kargbo  3 , G E Glass  4 , R Yang  6 , B J Cowling  1 , C Liu  2
Affiliations

Assessment of the severity of Ebola virus disease in Sierra Leone in 2014-2015

J Y Wong et al. Epidemiol Infect. 2016 May.

Abstract

The current Ebola virus disease (EVD) epidemic in West Africa is unprecedented in scale, and Sierra Leone is the most severely affected country. The case fatality risk (CFR) and hospitalization fatality risk (HFR) were used to characterize the severity of infections in confirmed and probable EVD cases in Sierra Leone. Proportional hazards regression models were used to investigate factors associated with the risk of death in EVD cases. In total, there were 17 318 EVD cases reported in Sierra Leone from 23 May 2014 to 31 January 2015. Of the probable and confirmed EVD cases with a reported final outcome, a total of 2536 deaths and 886 recoveries were reported. CFR and HFR estimates were 74·2% [95% credibility interval (CrI) 72·6-75·5] and 68·9% (95% CrI 66·2-71·6), respectively. Risks of death were higher in the youngest (0-4 years) and oldest (⩾60 years) age groups, and in the calendar month of October 2014. Sex and occupational status did not significantly affect the mortality of EVD. The CFR and HFR estimates of EVD were very high in Sierra Leone.

Keywords: Death; Ebola virus; severity.

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Figures

Fig. 1.
Fig. 1.
Daily incidence of cases of Ebola onset, hospitalization and deaths for all ages in Sierra Leone, between 23 May 2014 and 31 January 2015. (a) Daily numbers of onset. (b) Daily numbers of hospital admissions. (c) Daily numbers of deaths.
Fig. 2.
Fig. 2.
Real-time estimates of (a) the case fatality risk and (b) the hospitalization fatality risk in all probable and confirmed cases in Sierra Leone, between 23 May 2014 and 31 January 2015. Solid lines represent the posterior mean, dotted line show 95% credibility intervals.
Fig. 3.
Fig. 3.
Distribution of (a) the interval from symptom onset to reporting, (b) the interval from symptom onset to sample testing, and (c) the interval from sample collected to sample testing, in confirmed and probable Ebola virus disease cases in Sierra Leone, between 23 May 2014 and 31 January 2015.
Fig. 4.
Fig. 4.
Prevalence of Ebola hospitalized cases in Sierra Leone, between 23 May 2014 and 31 January 2015.
See this image and copyright information in PMC

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