Epidemiological update: Outbreak of Ebola virus disease in west Africa, 21 August 2014

epidemiological update

​Since December 2013 and as of 18 August, 2 473 cases of EVD, including 1 350 deaths have been reported, making this EVD outbreak the largest ever documented outbreak of EVD.

​On 8 August 2014, the World Health Organization declared the outbreak of Ebola Virus Disease (EVD) evolving in west Africa a Public Health Emergency of International Concern (PHEIC).

Since December 2013 and as of 18 August, 2 473 cases of EVD, including 1 350 deaths, have been reported, making this EVD outbreak the largest-ever documented outbreak of EVD. The number of reported cases and deaths exceeds the cases and deaths number of all historical outbreaks. It is also the largest outbreak in terms of geographical spread. As of today, no cases have been confirmed outside Guinea, Liberia, Nigeria, or Sierra Leone.

New cases continue to be reported in Guinea, Liberia and Sierra Leone. The most recent case in Nigeria was reported 16 August 2014. Since the epidemiological update of 14 August 2014, a 25% increase in number of EVD cases was observed between the 11 and 18 August 2014, corresponding to 498 new EVD cases and 281 deaths from the four countries together. The largest increase has been recorded in Liberia (302 cases in one week).

Figure 1: Weekly number of EVD cases in west Africa (Guinea, Sierra Leone, Liberia and Nigeria) from start of the outbreak to 18 August 2014* 

Source: adapted from WHO (Ebola virus disease, west Africa – update)

*Data for week 34 2014 are incomplete

 
In the four countries, cases have not only affected rural areas but also large cities (i.e. Conakry, Freetown, Monrovia and Lagos).
 

Figure 2: Distribution of EVD cases (confirmed, probable and suspected) by district in the affected countries from December 2013 to 16 August 2014

Source: Adapted from national situation reports and WHO (Ebola virus disease, west Africa – update).

Table: Overview of EVD cases and deaths per country (as of 18 August 2014)

Country

Number of cases

Number of deaths

Case Fatality Ratio

Guinea

579

396

68%

Liberia

972

576

59%

Nigeria

15

4

26%

Sierra Leone

907

374

41%

Total

2473

1350

54%

Source: Adapted from WHO (Ebola virus disease, West Africa – update)

 
The outbreak is rapidly evolving with a noticeable and constant increase in the number of EVD cases since early July 2014. Transmission continues to be very high in Liberia and Sierra Leone. On 19 August 2014, in response to the growing number of cases, the Liberian president declared a quarantine of the two most affected areas, including West Point (Monrovia).
 

Figure 3: Epidemic curves of EVD by week of reporting in Guinea, Liberia, Sierra Leone and Nigeria (as of 18 August 2014*)

Source: Adapted from WHO (Ebola virus disease, west Africa – update)

* Data for week 34 2014 are incomplete

WHO and international organisations are closely supporting the ministries of health of the affected countries in their EVD prevention, contact tracing, health care and control-related activities.
ECDC continues to monitor the situation closely.