Epidemiological update: Outbreak of Ebola virus disease in West Africa, 18 December 2014

There have been 6 915 reported deaths.

Since the last ECDC Epidemiological update, published on 12 December 2014, this represents an increase of 451 cases and 367 deaths. (WHO Situation summary, Data published on 11 December 2014; WHO Ebola response roadmap situation report, 17 December) 

Distribution of cases

Countries with widespread and intense transmission:

• Guinea: 2 416 cases and 1 525 deaths (as of 14 December 2014) - increase of 77 cases since 9 December
• Liberia: 7 797 cases and 3 290 deaths (as of 9 December 2014)- increase of 32 cases since 7 December
• Sierra Leone: 8 356 cases and 2 085 deaths (as of 14 December 2014) - increase of 342 cases since 7 December

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

• United States: four cases including one death. The last infected person tested negative on 11 November 2014 in New York.
• Mali: eight cases, six deaths.
• Nigeria, Senegal and Spain are declared free of EVD after having reported cases related to this current epidemic in West Africa.

Please note that since the beginning of November 2014, WHO does not consistently report probable and suspected cases for the three most affected countries due to the high proportion of cases that are later re-classified.

 

Figure 1 . Distribution of cases of EVD by week of reporting in Guinea, Sierra Leone, Liberia, Nigeria, Senegal and Mali, weeks 48/2013 to 51/2014, as of 17 December 2014

 

* In week 45/2014, the WHO carried-out a 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. WHO Ebola response roadmap situation report, 5 November. ** According to the 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). WHO Ebola response roadmap situation report, 26 November

 

Situation in the affected West African countries

According to WHO, in the three countries with widespread and intense transmission, reported case incidence seems to be fluctuating in Guinea, declining in Liberia, but still increasing in Sierra Leone even though slower than in previous weeks. 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. More than 80% of the registered contacts associated with known cases of EVD in these countries, are being traced. Social mobilization continues to be fundamental to control the spread of disease.

As reported in the latest WHO Response Roadmap the case fatality rate in the three intense-transmission countries among all cases for whom a definitive outcome is recorded is 70% and between 58 and 60% in hospitalized patients. The number of EVD reported cases in the three most affected countries, is about the same in males and females.

 

Table 1. Cumulative number of confirmed and probable cases by sex and age group in Guinea, Liberia, and Sierra Leone

*Excludes cases for which data on sex are not available. **Excludes cases for which data on age are not available.

**Population figures are based on estimates from the United Nations Department of Economic and Social Affairs.

 

The bed capacity in the EVD treatment facilities seems to be sufficient to treat and isolate all reported EVD-infected patients in each of the three intense-transmission countries, although due to uneven distribution of beds and cases there are serious shortfalls in some areas.

As reported by the WHO, no new cases have been reported in Mali since 24 November. The last infected person in Mali tested negative for the second time on 6 December, and was discharged from hospital on 11 December. All identified contacts connected with both the initial case and the outbreak in Bamako have now completed the 21-day follow-up. WHO Ebola response roadmap situation report, 17 December

Figure 2. Distribution of cases of EVD by week of reporting, Guinea, Liberia and Sierra Leone, as of week 51/2014

* 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. WHO Ebola response roadmap situation report, 5 November

** 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 50/2014)

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

Situation among healthcare workers

As of 17 December WHO reported a total of 649 health-care workers (HCWs) infected with EVD, 365 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 14 December 2014

 

Source: Data are based on official information reported by Ministries of Health. WHO Ebola response roadmap situation report, 17 December

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.