Ebola: 6- to 12-day incubation, fever, headache, weakness, dizziness, and diarrhea in most

Clinical Question

What is the incubation period and typical clinical presentation of a patient with Ebola in the current large outbreak in West Africa?

Bottom Line

In the current large outbreak of Ebola virus disease (EVD) in West Africa, the incubation period is 6 days to 12 days and the most common signs and symptoms are fever, headache, weakness, dizziness, and diarrhea. It is sobering to note that 5 of the authors of this report died prior to its publication. (LOE = 3b)


Schieffelin JS, Shaffer JG, Goba A, et al; KGH Lassa Fever Program; Viral Hemorrhagic Fever Consortium; WHO Clinical Response Team. Clinical illness and outcomes in patients with Ebola in Sierra Leone. N Engl J Med 2014;371(22):2092-100.  [PMID:25353969]

Study Design

Diagnostic test evaluation




Inpatient (any location)


This is the first detailed description of the clinical presentation of patients in the large EVD outbreak in West Africa. Physicians in other countries have been instructed to ask patients about recent travel to West Africa if they present with symptoms that could represent EVD. However, some physicians may mistakenly believe that most patients have hemorrhagic symptoms, which is not the case. In this report, 213 patients presented with a suspected case of EVD, and 105 tested positive. The case fatality rate was 74%, and increased with increasing age and increasing viral load at presentation. The most common signs and symptoms were fever (89%), headache (80%), weakness (66%), dizziness (60%), and diarrhea (51%). Other common symptoms included abdominal pain (40%), sore throat (34%), vomiting (34%), and conjunctivitis (31%). Only 1 patient presented with hemorrhagic symptoms, which is different from many previous outbreaks. Patients with dizziness, weakness, diarrhea, and/or a higher fever had a significantly higher case fatality rate than those without those symptoms. The average time from the onset of symptoms to presentation was 5.7 days, and the researchers estimated an incubation period of 6 days to 12 days. Patients with fatal EVD had higher blood urea nitrogen and serum creatinine levels, which would be consistent with greater dehydration, and higher values of alanine aminotransferase and aspartate aminotransferase, indicating hepatocellular damage (although the latter difference was not statistically significant).

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