The Ebola outbreak probably started months ago in central Africa and spread undetected until a super-spreader event in early May, possibly a funeral, World Health Organization officials said.
The rare Bundibugyo strain circulated for “a couple months” before being identified in blood samples on May 15, Anais Legand, WHO’s technical lead for viral hemorrhagic fevers, said at a briefing Wednesday. The first confirmed death took place April 20, and experts used social media posts to reconstruct the recent progress of the virus after the super-spreader event on May 5.
Two factors complicated efforts to identify the virus earlier. Authorities used tests for a different Ebola strain, resulting in false negatives, and many symptoms can resemble those of malaria, according to Abdirahman Mahamud of the agency’s Health Emergencies Program.
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