Rapid Risk Assessment: Outbreak of Ebola Virus disease in West Africa – 12th update, 1 July 2015

Risk assessment
Citation Link

European Centre for Disease Prevention and Control. Outbreak of Ebola virus disease in West Africa. 12th update, 30 June 2015. Stockholm: ECDC; 2015.

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​This is the 12th update of the rapid risk assessment on the outbreak of Ebola virus disease in West Africa. It provides the latest figures on cases for the week 14-21 June 2015, re-assesses the risk of importation of Ebola virus disease into the EU and discusses options for risk reduction.

Executive summary

The 20 new confirmed cases reported in the week from 14 to 21 June indicate that the weekly incidence of new cases, which has levelled off over the last 10 weeks, remains unchanged. 
Low intensity transmission continues due to incomplete contact tracing, inadequate case detection and management of new infections. The area of transmission has expanded slightly in recent weeks and, for the first time in several months, two healthcare workers were reported to have become infected. Cases continue to be reported from the capital cities of both Guinea and Sierra Leone. Cases are still occurring outside known transmission chains. Liberia was declared Ebola-free on 9 May 2015, however a new confirmed case was reported on Monday 29 June. This case has not yet been acknowledged by WHO.

Risk of EVD spreading in West Africa

The risk of EVD spreading to countries that share borders with Guinea and Sierra Leone remains high due to frequent cross-border movement of people and insufficient Ebola surveillance in the border areas. The rainy season, which started in April and usually lasts until November, makes transportation of staff and equipment difficult, and could further impair outbreak control efforts, particularly in hard-to-reach areas.

Possible risk of re-emergence of EVD transmission in countries with previous widespread transmission

Resurgence of the Ebola outbreak remains a possibility until all contacts of all cases have been identified and monitored for 21 days without developing symptoms. There is a risk that Ebola virus may be reintroduced and transmission re-established in areas that have been declared Ebola-free.
Failing to achieve zero cases in all regions of the two countries within the next few months could result in a low-intensity, persistent human-to-human epidemic in West Africa, with recurrent surges of intensified transmission. Another possible source for re-emergence of EVD transmission in countries where intense, widespread transmission has occurred and subsequently declined are through the animal reservoir or re-introduction through the importation of an infectious case.

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