Epidemiological update: Outbreak of Ebola virus disease in West Africa

epidemiological update

​The outbreak of Ebola virus disease affecting West Africa continues. ECDC provides a weekly update on the evolving situation.

Since December 2013 and as of 23 November 2014, WHO has reported 15 935 confirmed, probable and suspected cases of Ebola virus disease (EVD) in six affected countries (Guinea, Liberia, Mali, Sierra Leone, Spain and the United States of America) and two previously affected countries (Nigeria and Senegal).There have been 5 689 reported deaths. This is an increase of 780 cases and 269 deaths since 16 November 2014.

Distribution of cases

Countries with widespread and intense transmission:• Guinea: 2 134 cases and 1 260 deaths (as of 23 November 2014),• Liberia: 7 168 cases and 3 016 deaths (as of 22 November 2014),• Sierra Leone: 6 599 cases and 1 398 deaths (as of 23 November 2014).

Countries with an initial case or cases, or with localised transmission:• United States: four cases including one death,• Spain: one case, no deaths,• Mali: eight cases, six deaths,• Nigeria: 20 cases and eight deaths. Nigeria was declared Ebola free on 19 October 2014,• Senegal: one confirmed imported case. Senegal was declared Ebola free on 17 October 2014.

Figure 1. Distribution of cases of EVD by week of reporting in Guinea, Sierra Leone, Liberia, Nigeria, Senegal and Mali, weeks 48/2013 to 48/2014, as of 26 November 2014.

* In week 45/2014, WHO carried-out retrospective correction in the data resulting in reporting 299 fewer cases resulting in a negative value for new cases in week 45 which is not plotted.  ** According to WHO the marked increase in the cumulative total number of cases in week 43 is due to a more comprehensive assessment of patient databases leading to 3 792 additional reported cases. However, these cases have occurred throughout the epidemic period . The green line represents the trend based on a five week moving average plotted on the fifth week of the moving average window. The figure includes cases in Nigeria (20), Senegal (1) and Mali (4).

Situation in specific West African countries

According to WHO, in the three countries with widespread and intense transmission, reported case incidence seems stable in Guinea, stable or declining in Liberia, but still increasing in Sierra Leone. All administrative districts in Liberia and Sierra Leone have reported at least one confirmed or probable case of EVD since the start of the epidemic. Cases and deaths continue to be under-reported.
 
On 25 November 2014, WHO confirmed two additional cases of EVD in Bamako, Mali. The first case was the 23-year-old fiancée of a 25-year-old nurse who attended the Imam from Guinea (the index case in this outbreak) and the second case is part of a family of previously confirmed and deceased patients. In total, eight cases of EVD, including six deaths, have been reported in Mali (seven in Bamako and one in Kayes). To date, all seven cases in Bamako can be linked to contact with an Imam who developed symptoms on 17 October in his native village of Kourémalé, Guinea, and arrived in Bamako on 25 October for treatment at the Pasteur Clinic. All identified contacts connected with this initial case have now completed 21-days follow-up. Among the cases in Bamako, two are healthcare workers (HCWs) who cared for the imported case from Guinea. According to WHO, as of 24 November 2014, 285 of 288 contacts linked with the current outbreak in Bamako have been followed-up.
 

Figure 2. Distribution of cases of EVD by week of reporting, Guinea, Liberia and Sierra Leone, as of week 48/2014.

* The marked increase in the number of cases reported in Sierra Leone (week 44) and Liberia (week 43) results from a more comprehensive assessment of patient databases. The additional 3 792 cases have occurred throughout the epidemic period. Source: Data are based on official information reported by ministries of health up to the end of 2 November for Guinea and Sierra Leone and 31 October for Liberia. 
** In week 45/2014, WHO reported 476 fewer cases than the week before in Sierra Leone due to retrospective corrections.

§ In week 44/2014, WHO reported zero cases for Liberia.

Figure 3. Distribution of cases of EVD by week of reporting in Guinea, Sierra Leone, Liberia and Mali (as of week 47/2014).

Source: Data from ministries of health reports (suspected, probable and confirmed cases).

Situation among healthcare workers

As of 16 November WHO reported a total of 592 health-care workers (HCWs) infected with EVD, 340 of whom have died. According to WHO early indication a substantial proportion of infections among HCWs occurred outside the context of Ebola treatment and care centres.
 

Table 2. Number of Ebola cases and deaths among healthcare workers, as of 23 November 2014.

Country Healthcare worker cases (% of reported cases) Healthcare worker deaths (% of reported deaths)
Guinea 97 (4.5) 56 (4.4)
Liberia 342 (4.8) 172 (5.7)
Mali 2 (25.0) 2 (33.3)
Nigeria 11 (55.0) 5 (62.5)
Sierra Leone 136 (2.1) 105 (7.5)
Spain 1 (100) 0
United States 3 (75.0) 0
Total 592 (3.7) 340 (6.0)

Source: Data are based on official information reported by Ministries of Health.
 

Situation outside West Africa

USA
No new autochthonous EVD cases have been reported since 23 October. The latest autochthonous reported case concerns a medical aid worker who volunteered in Guinea and recently returned to the United States. He was hospitalised in New York City and was discharged healthy on 11 November 2014.Spain
No new cases have been reported since 6 October when a healthcare worker was infected while caring for an Ebola-infected patient in Madrid. She recovered and tested negative for EVD on 19 October. A second negative test was obtained on 21 October. All 83 contacts of the HCW have completed a 21-day follow-up. Spain will be declared free of EVD next 42 days after the date of the second negative test if no new cases are reported.

Medical evacuations and repatriations from EVD-affected countries

Twenty two individuals have been evacuated or repatriated from the EVD-affected countries. As of 27 November, there have been 11 medical evacuations of confirmed EVD-infected patients to Europe (three to Germany, three to Spain, two to France, one to the UK, one to Norway and one to Italy). Two persons exposed to Ebola have been repatriated to the Netherlands and tested negative. One individual was evacuated to Switzerland and was not confirmed for EVD in September.
 
The most recent case is an Italian doctor who was medically evacuated from Sierra Leone on 24 November. According to the Italian Ministry of Health, he was working in the Medical Centre of the NGO Emergency in Sierra Leone when he was diagnosed with EVD. The patient, a 50-year-old Sicilian man, was transported to the National Institute for Infectious Diseases (INMI) Lazzaro Spallanzani in Rome and was hospitalised in a high isolation unit to receive the appropriate treatment.

Table 3. Medical evacuation and repatriation from EVD-affected countries, as of 28 November 20144. Medical evacuations and repatriations from EVD-affected countries, as of 28 November 2014.

Date of Evacuation

Evacuated from

Evacuated to

Profession

Status

Confirmed

Citizenship

02 August 2014

Liberia

Atlanta (USA)

Healthcare worker

Discharged

Yes

USA

05 August 2014

Liberia

Atlanta (USA)

Healthcare worker

Discharged

Yes

USA

06 August 2014

Liberia

Madrid (Spain)

Healthcare worker

Death

Yes

Spain

24 August 2014

Sierra Leone

London (United Kingdom)

Healthcare worker

Discharged

Yes

UK

27 August 2014

Sierra Leone

Hamburg (Germany)

Epidemiologist

Recovered

Yes

Senegal

04 September 2014

Monrovia, Liberia

Omaha (USA)

Physician (obstetrician)

Discharged

Yes

USA

09 September 2014

Kenema, Sierra Leone

Atlanta (USA)

Physician

Discharged

Yes

USA

14 September 2014

Sierra Leone

Leiden (the Netherlands)

Healthcare worker

Discharged

No

the Netherlands

14 September 2014

Sierra Leone

Leiden (the Netherlands)

Healthcare worker

Discharged

No

the Netherlands

19 September 2014

Liberia

Paris (France)

Healthcare worker

Discharged

Yes

France

22 September 2014

Sierra Leone

Madrid (Spain)

Healthcare worker

Death

Yes

Spain

22 September 2014

Sierra Leone

Geneva (Switzerland)

Healthcare worker

Admitted

Unknown

Non-Swiss

28 September 2014

Sierra Leone

Maryland (USA)

Healthcare worker

Admitted

Unknown

USA

02 October 2014

Sierra Leone

Frankfurt (Germany)

Healthcare worker

Stable

Yes

Uganda

02 October 2014

Liberia

Omaha (USA)

Cameraman

Discharged

Yes

USA

06 October 2014

Sierra Leone

Oslo (Norway)

Healthcare worker

Discharged

Yes

Norway

08 October 2014

Liberia

Leipzig (Germany)

Laboratory worker

Death

Yes

Sudan

01 November 2014

Sierra Leone

Paris (France)

UN worker

Unknown

Yes

Sierra Leone

15 November 2014

Sierra Leone

Nebraska (USA)

Healthcare worker

Death

Yes

USA

20 November 2014

Sierra Leone

Geneva (Switzerland)

Healthcare worker

Unknown

Yes

Cuba

21 November 2014

Mali

Madrid (Spain)

Healthcare worker

Unknown

No

Spain

24 November 2014

Sierra Leone

Rome (Italy)

Healthcare worker

Admitted

Yes

Italy

Figure 4: Medical Evacuations and repatriations from EVD-affected countries, as of 28 November 2014.

Download the data

  • Epi-curve data Cumulative number of cases and deaths for the West African countries with reported EVD cases. Source: WHO
  • Map data Cumulative number of cases and deaths at subnational level in the West African countries with reported EVD cases. Source: National situation report.For those weeks without reported data, the most recent figures were used as best estimate of the number of case.