The outbreak is now confirmed to be caused by a strain of ebolavirus with very close homology (98%) to the Zaire ebolavirus. This is the first time the disease has been detected in West Africa. Cases were first reported from forested areas in south-eastern Guinea.
The outbreak has rapidly evolved and several districts and Conakry have reported cases and deaths caused by EVD. A small number of suspected cases and deaths has also been reported from neighbouring countries with all of them having crossed from Guinea. Confirmed cases have been reported from Guinea and Liberia.