The levels of virus present in the blood for patients with Ebola virus disease (EVD) are strong predictors of fatality, according to a new study in PLOS Medicine.
A research team at the Pasteur Institute in Paris and Dakar, Senegal, analyzed the laboratory and epidemiologic records of 699 patients with EVD to determine the association between viremia and case fatality ratio (CFR). The EVD diagnoses of patients hospitalized in the Conakry area, Guinea, between March 1, 2014, and Feb. 28, 2015, were confirmed by reverse transcription polymerase chain reaction. Researchers discovered that, in the week following EVD symptom onset, patient viremia remained stable, and that the CFR increased with level of viremia.
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The CFR for patients with low-, intermediate-, and high viremia was 21%, 53%, and 81%, respectively. Compared with adults aged 15-44 years, children younger than 5 years and adults aged 45 years and older had higher CFR, but children aged 5-14 years had a lower CFR. When the average viremia increased 10-fold in July 2014, CFR increased as well, by 14%.
Study authors cautioned that their findings may not translate to cases outside the hospital setting, but that knowledge of the relationship between viremia levels and CFR could help clinicians more accurately assess the efficacy of treatments for EVD in nonrandomized trials.
“This finding suggests that heterogeneity in historical CFR estimates among patients, [Ebola treatment centers], and over time may at least partly be explained by variations in viremia and underscores that more valid estimates of the influence of other factors, including treatment effects, might be obtained by adjusting for differing levels of viremia among patients,” the authors wrote.
The study was funded by the French Government’s Investissement d’Avenir program, Laboratoire d’Excellence “Integrative Biology of Emerging Infectious Diseases,” the U.S. National Institute of General Medical Sciences MIDAS (Models of Infectious Disease Agent Study) initiative, the AXA Research Fund, and the Seventh Framework Programme of the European Union. The authors declared no conflicts of interest.
Read the entire study on the PLOS Medicine website.
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