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.