CENTER FOR DISEASE RESEARCH AND POLICY July 24, 2015
(Also scroll down for: Ebola case definition quandary; Public health worker Ebola unease)
Researchers found that the World Health Organization (WHO) Ebola case definition has a specificity of only 31.5%, and they noted that 9% of Ebola patients reported neither a fever nor any Ebola risk exposure, calling into question WHO norms, according to a large study yesterday in The Lancet Infectious Diseases.
Researchers from Britain and Sierra Leone analyzed data on 850 suspected and 724 lab-confirmed Ebola patients who presented to the holding unit of Connaught Hospital in Freetown from May 29 to Dec 8, 2014. Fever or history of fever (n=599, 83%), intense fatigue or weakness (495, 68%), vomiting or nausea (365, 50%), and diarrhea (294, 41%) were the most common presenting symptoms in suspected cases.
Based on data from these patients, the investigators found the sensitivity of the WHO case definition to be 79.7%, which means about 20% of true Ebola cases would be missed (false-negatives). They found the specificity of the case definition to be 31.5%, which means 68.5% of patients who would be selected for admission would not actually have Ebola virus disease (false-positives).
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