Epidemiological update: outbreak of Ebola virus disease in West Africa

epidemiological update

​Since December 2013 and as of 2 November 2014, WHO has reported 13 042 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 4 818 reported deaths.

This is 525 cases and 133 deaths less than in the previous update of 31 October (Figure 1). The WHO revised the cumulative number of cases and deaths for a second week saying that the revision was caused by a change in the source of the data. Previously WHO had combined patient databases and country reports from health ministries and WHO offices, but it has switched to relying entirely on the country reports.

Distribution of cases

 
Countries with widespread and intense transmission
 

  • Guinea: 1 731 cases and 1 041 deaths as of 2 November 2014;
  • Liberia: 6 525 cases and 2 697 deaths as of 31 October 2014;
  • Sierra Leone: 4 759 cases and 1 070 deaths as of 2 November 2014;

 

Countries with an initial case or cases, or with localised transmission:
 

  • Mali: one confirmed imported case from Guinea was reported in Kayes, Mali on 23 October. The case died on 24 October;
  • United States: four cases including one death, the last confirmed case occurred in New York on 23 October 2014;
  • Spain: one case, no deaths. The case is the result of secondary transmission in Spain to a nurse who cared for an EVD patient who had been evacuated from Liberia. The nurse was isolated on 6 October 2014. This case tested negative for Ebola for a second time on 21 October 2014;
  • 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 45/2014*

 * The bar for week 45/2014 is not presented as there are 525 cases less than in the previous update of 31 October. The solid 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 imported cases in Senegal (1) and Mali (1). (See: World Health Organization. Ebola response roadmap situation report. 5 November 2014 [Internet]. Geneva: WHO; 2014) 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 [2]. (See: World Health Organization. Ebola response roadmap situation report. 29 October 2014 [Internet]. Geneva: WHO; 2014)
 
 

Situation in Guinea, Sierra Leone and Liberia

According to WHO, the weekly incidence appears to be stable in Guinea at the country level. In Sierra Leone the weekly incidence continues to rise, while in Liberia it appears to be declining. In all three countries, EVD transmission remains persistent and widespread, particularly in the capital cities. All administrative districts in Liberia and Sierra Leone have reported at least one confirmed or probable case of EVD since the outbreak began. Cases and deaths continue to be under-reported in this outbreak.
 

Figure 2. Distribution of cases of EVD by week of reporting in the three countries with widespread and intense transmission as of week 45/2014*

 * The bar for week 45/2014 in Guinea does not represent a complete calendar week; the marked increase in the number of cases reported in Sierra Leone and Liberia in weeks 43 and 44 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 (See: World Health Organization. Ebola response roadmap situation report. 5 November 2014 [Internet]. Geneva: WHO; 2014)
 

Figure 3. Distribution of cases of EVD by week of reporting in Guinea, Sierra Leone and Liberia (as of week 44/2014)

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

 

Situation among healthcare workers in West Africa

As of 2 November 2014, WHO reported 546 healthcare workers (HCWs) infected with EVD of whom 310 died. Table 1 details the distribution of cases and deaths among healthcare workers. Four HCWs were infected between 27 October and 2 November. See: World Health Organization. Ebola response roadmap situation report. 5 November 2014 [Internet]. Geneva: WHO; 2014).
 
 

Table 1. Number of Ebola cases and deaths in healthcare workers in West Africa

 

Country Healthcare worker cases (% of re​​ported cases) Healthcare worker deaths (% of reported deaths)
Guinea 88 (5.1) 46 (4.4)
Liberia 315 (4.8) 157 (5.8)
Sierra Leone 128 (2.7) 102 (9.5)
Nigeria 11 (55.0) 5 (62.5)
Spain 1 (100) 0
United States of America 3 (75.0) 0
Total 546 (4.2) 310 (6.4)

Source: Data are based on official information reported by Ministries of Health (See: World Health Organization. Ebola response roadmap situation report. 5 November 2014 [Internet]. Geneva: WHO; 2014).
 
 

Situation outside of West Africa

 USANo new EVD cases have been reported since 23 October. The latest reported case concerns a medical aid worker who volunteered in Guinea and recently returned to the United States. He is currently hospitalised.
 SpainNo 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. Spain will be declared free of EVD 42 days after the date of the second negative test if no new cases are reported.
 MaliOn 23 October, Mali reported its first confirmed case of EVD. The patient was a 2-year old girl who travelled from Guinea with her grandmother to Mali and died on 24 October in Kayes. The patient was symptomatic for much of the journey. At present, 108 contacts are being monitored. This includes 79 in Kayes and 29 in Bamako.
 Medical evacuations from EVD-affected countriesSeventeen individuals have been evacuated or repatriated from the EVD-affected countries (Table 2, Figure 4). As of 6 November, there have been nine medical evacuations of confirmed EVD-infected patients to Europe (three to Germany, two to Spain, one to the UK, one to France, one to Norway and one to Switzerland); two persons exposed to Ebola have been repatriated to the Netherlands.
 

Table 2. Medical evacuation and repatriation from EVD-affected countries, as of 6 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 Lausanne (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

 

 

Figure 4. Medical evacuations and repatriations from EVD-affected countries, as of 06 November 2014

 

 
 
 

Recent scientific publications 

In the past week, new publications provided additional information about the clinical presentation on EVD case series in Conakry (Guinea) and Kenema (Sierra Leone). Common symptoms for all the EVD patients, in all locations, were fever and weakness. In almost half of the cases the symptoms were accompanied by gastro-intestinal symptoms (diarrhoea, nauseas, vomiting). During hospitalization the frequency of haemorrhagic signs or bleedings varies across studies with 2% in Sierra Leone (n=43 EVD cases) and 26% and 51% in case series in Conakry (n=90 and n=37 respectively).
 Bah EI, Lamah M-C, Fletcher T, Jacob ST, Brett-Major DM, Sall AA, et al. Clinical Presentation of Patients with Ebola Virus Disease in Conakry, Guinea. N Engl J Med. 2014;0(0):null.Schieffelin JS, Shaffer JG, Goba A, Gbakie M, Gire SK, Colubri A, et al. Clinical illness and outcomes in patients with Ebola in Sierra Leone. N Engl J Med. 2014 Oct 29.Barry M, Traoré FA, Sako FB, Kpamy DO, Bah EI, Poncin M, et al. Ebola outbreak in Conakry, Guinea: Epidemiological, clinical, and outcome features. Med Mal Infect. 2014 Oct 23
 

Chronology of events

See Key dates of Ebola virus disease outbreak in West Africa.
 

 

 
Download the data

 

  • EVD epicurve dataCumulative number of cases and deaths for the five West African countries with reported EVD cases (Liberia, Guinea, Sierra Leone, Nigeria, Senegal). Source: WHO
  • EVD map dataCumulative number of cases and deaths at subnational level of the five West African countries with reported EVD cases (Liberia, Guinea, Sierra Leone, Nigeria, Senegal). Source: National situation reportFor those weeks without reported data, the most recent figures were used as best estimate of the number of case).

 

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