Epidemiologic characteristics of Ebola virus disease outbreak in Liberia

Objective To analyze the epidemiologic characteristics of Ebola virus disease(EVD) outbreak in Liberia, evaluate related prevention and control effort, and provide evidence for China's anti EVD aid in West Africa.Methods The incidence data of EVD was collected from the web sites of Liberian ministry of health, WHO and European Centre for Disease Prevention and Control; and a descriptive epidemiologic analysis was conducted.Results As of 15 March, 2015, a total of 9645 EVD cases had been reported in Liberia, including 4252 deaths, the case fatality rate was 44%. Among health care workers(HCWs), 372 cases, including 180 deaths, were reported, accounting for 39% of HCWs infected with Ebola virus in three West African countries(Liberia, Guinea and Sierra Leone) and 3.9% of total EVD cases in Liberia. The case fatality rate in HCWs was 48%. The gender specific difference in EVD incidence had no statistical significance. The population was generally susceptible and the EVD incidence in people aged 45 years was 3 times higher than that in people aged 15 years; All the close contacts of EVD cases were tracked. From late March to April 23, 2014, the EVD epidemic was temporarily controlled, but in mid-June, the second wave of EVD epidemic occurred, the case number increased exponentially and peaked in September, then declined significantly from mid-September to mid-December, the incidence of EVD was low, the epidemic tended to be controlled. On 15 March 2015, no case was reported any more.Conclusion The failure in control of EVD epidemic in Liberia might be explained by the fall behind economy, traditional custom, limited prevention and control resources and poor implementation of early prevention and control measures. The lessons learnt from Liberia's EVD prevention and control practice are important for the prevention and control of emerging and imported communicable diseases in China in the future.