Rapid risk assessment: Outbreak of Ebola virus disease in West Africa. 11th update, 11 May 2015
Developments since the tenth update As of 8 May 2015, WHO has reported 26 683 cases, including 11 022 deaths, linked to the West African epidemic of Ebola virus disease (EVD) with onset in December 2013. Nine countries have reported EVD cases. Guinea, Liberia and Sierra Leone have experienced widespread and intense transmission. Mali, Nigeria, Senegal, Spain, the United Kingdom and the USA have at some point reported imported cases or import-related local transmission linked to the epidemic in West Africa, but all six countries have been declared Ebola-free.
Guinea and Sierra Leone still report cases whereas Liberia has not reported a confirmed case since 27 March and was declared Ebola-free by the World Health Organization (WHO) on 9 May 2015 after 42 days without confirmed cases . Liberia’s last case was a woman in the greater Monrovia area who developed symptoms on 20 March and died on 27 March.
However, the epidemic is not being controlled at the same pace in the two other countries, and there is a risk that transmission will be reintroduced to areas and countries that have been declared Ebola-free.
The latest WHO report indicates that the number of new cases continues to decrease. Eighteen cases were reported from Guinea and Sierra Leone for the week leading up to 6 May. This is the lowest weekly number of cases reported in 2015. Sierra Leone and Guinea have reported low number of cases for five consecutive weeks.
The geographical area of transmission is shrinking in both Guinea and Sierra Leone. In Guinea the affected area is still larger than in Sierra Leone. Transmission is now concentrated in districts along the Guinean-Sierra Leonean border.
ECDC published a public health development following new evidence related to possible sexual transmission of EVD . WHO published ‘Sexual transmission of the Ebola Virus: evidence and knowledge gaps’ providing interim advice for the Ebola survivors .
The West African EVD epidemic was declared a Public Health Emergency of International Concern (PHEIC) by the Director General of WHO on 8 August 2014 on the recommendation of the Emergency Committee. The Committee met for the fifth time on 9 April 2015 and concluded that the event continues to constitute a PHEIC and recommended that all previous temporary recommendations should be extended. The Committee strongly reiterated the need for continued exit screening in the affected countries for at least 42 days after the last case has twice tested negative for Ebola.
There are now concerns about the risk of outbreaks of vaccine-preventable diseases in the Ebola-affected countries. The interruption of immunisation activities since the start of the epidemic has resulted in the accumulation of susceptible individuals in Guinea, Liberia and Sierra Leone. There is an ongoing outbreak of measles in Guinea, and there is a risk of vaccine-preventable diseases spreading in all three countries.