Case fatality rates of Ebola virus diseases: a meta-analysis of World Health Organization data

Abstract

Objective: Our objective was to estimate the case fatality rates of Zaire, Sudan, and Bundibugyo Ebola species, responsible for sometimes-lethal hemorrhagic fevers.

Methods: We performed a meta-analysis of World Health Organization data on outbreaks of infections due to theses species.

Results: Twenty outbreaks, including the current one, were studied. The estimated case fatality rate was 65.4% (CI 95% [54.6%; 75.5%]) and varied among the outbreaks. A species effect was identified, with a higher case fatality rate for the Zaire species than for Sudan and Bundibugyo species. The case fatality rate of the Zaire species tended to decrease with time.

Conclusion: The case fatality rates associated with these 3 species was high. A great variability was observed. It could be explained partly by a species effect and by the decrease of Zaire species case fatality rate, with time.

Keywords: Case fatality rate; Ebola; Meta-analysis; Méta-analyse; Taux de létalité; Ébola.