Symptom- and Laboratory-Based Ebola Risk Scores to Differentiate Likely Ebola Infections

The authors reviewed retrospective data from both positive and negative Ebola patients in Sierra Leone to develop two risk scores on the likelihood of Ebola infection among patients with suspected or confirmed Ebola virus disease. The Ebola symptom-based risk (ESR) score was based on headache, diarrhea, difficulty breathing, nausea/vomiting, loss of appetite, and conjunctivitis. If available, laboratory test results for alanine transaminase, creatine kinase, creatinine, and total bilirubin were added to the ESR score to calculate the Ebola symptom- and laboratory-based (ESLR) score. Among suspected patients who tested positive for Ebola virus disease, the ESR score categorized more than 70% and the ESLR score categorized more than 90% as high risk. The risk scores may be useful in separating patients who meet the case definition by their likeliness of infection and implementing greater protections and directing more resources to those with higher risk scores while awaiting laboratory confirmation of disease.