(HealthDay News) — Based on data from the first nine months of the Ebola virus disease (EVD) epidemic, the numbers of cases are predicted to continue increasing, according to a study published online September 23 in the New England Journal of Medicine.

Bruce Aylward, MD, from the World Health Organization in Geneva, and colleagues from the WHO Ebola Response team analyzed a subset of data from 3,343 confirmed and 667 probable Ebola cases from Guinea, Liberia, Nigeria, and Sierra Leone.

The researchers found that most patients were aged 15–44 years and 49.9% were male. Among individuals with known clinical outcome of infection, the case fatality rate was estimated at 70.8%. The course of infection, including signs and symptoms, 11.4-day incubation period, and 15.3-day serial interval were similar to those of other EVD outbreaks. The estimated current reproduction numbers were 1.81, 1.51, and 1.38 for Guinea, Liberia, and Sierra Leone, with corresponding doubling times of 15.7, 23.6, and 30.2 days, respectively. The predicted cumulative reported numbers of confirmed and probable cases are 5,740 in Guinea, 9,890 in Liberia, and 5,000 in Sierra Leone by November 2, 2014, assuming no change in the control measures for the epidemic.

“Without drastic improvements in control measures, the numbers of cases of and deaths from EVD are expected to continue increasing from hundreds to thousands per week in the coming months,” the authors write.

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