How common is Ebola virus hemorrhagic fever?
Until recently, only three outbreaks of Ebola hemorrhagic fever among people had been reported. The first two outbreaks were in 1976: one in Zaire and one in western Sudan. These were large outbreaks, resulting in more than 550 cases and 340 deaths. The third outbreak, in 1979 in Sudan, was smaller, with 34 cases and 22 fatalities. During each of these outbreaks, a majority of cases occurred in hospital settings under the challenging conditions of the developing world. These conditions, including a lack of adequate medical supplies and the frequent reusing of needles and syringes, played a major role in the spread of the disease. The outbreaks were quickly controlled when appropriate medical supplies and equipment were made available and quarantine procedures were used. The source of the Ebola virus in nature remains unknown. In an attempt to identify the source, investigators tested thousands of specimens from animals captured near the outbreak areas, but their efforts were unsuccessf
