Epidemiological update: outbreak of Ebola virus disease in West Africa

epidemiological update

Since December 2013 and as of 14 September 2014, WHO reports 5 347 cases of Ebola virus disease (EVD), including 2 630 deaths, in Guinea, Liberia, Nigeria and Sierra Leone.  

This is the first outbreak of EVD in West Africa and it is unprecedented in size and geographical distribution, affecting densely populated urban areas.

Three-hundred and eighteen of the cases occurred in healthcare workers, including 151 deaths. The outbreak continues to increase rapidly and the reported figures are believed to be underestimations of the real magnitude.

WHO reported 959 new cases and 404 deaths since the previous ECDC update of 12 September and the number of cases is expected to pass  20 000 by the end of 2014. 
To date, no confirmed cases have been reported outside Guinea, Liberia, Nigeria or Sierra Leone, except for one imported case in Senegal (a Guinean citizen who arrived from Guinea).

Source: adapted from WHO, data for week 38 are incomplete


Distribution of confirmed, probable and suspected EVD cases by district and week of reporting, weeks 33-38, 2014*

*Source: adapted from national situation reports, when availableData for week 38 are incomplete

Cases, deaths and case-fatality ratios in the EVD-affected countries in West Africa, as of 14 September 2014, week 2014-38

​Country ​Cases Deaths ​Case-fatality ratio
Guinea​ ​942 601​ 63.8%​
Sierra Leone ​1673 562​ 33.6%​
Liberia ​2710 1459 53.8​
Nigeria ​21 ​8 38.1%​
​Senegal ​1 0​ 0.0%​
​TOTAL ​5347 2630​ 49.2%​

Source: adapted from WHO and Senegal Ministry of Health

 Distribution of cases of Ebola virus disease by week of reporting in Guinea, Liberia and Sierra Leone, as of 14 September 2014, week 2014-38

Source: Adapted from WHO, data from week 38 are incomplete