THE FOLLOWING TEXT IS FOR THE QUESTIONS(1) Ebola virus disease (EVD) is one of the deadliest diseases and was discovered in 1976 when two fatal outbreaks of dengue fever occurred in Central Africa. The first outbreak occurred in a village near the Ebola River (the virus named after) in Congo, while the second one occurred in South Sudan.

(2) At the beginning, the outbreak was assumed by public health officials to be a single event when a person was infected after traveling between the two locations. However, it was then identified by the scientists that the two outbreaks were caused by two genetically different viruses: Zaire Ebola virus and Sudan Ebola virus. Later, the scientists concluded that the virus actually originated in two different locations and spread independently to other people in each of the affected area.

(3) Based on a certain data, epidemiologists suggested that the Ebola virus had existed long before the outbreak occurred. Population growth, forest exploration, and direct interactions with wildlife (such as consumption of wild animal meat) were the external factors that might have contributed to the spread of the Ebola virus.

(4) Since the discovery of the Ebola virus in 1976, most cases of Ebola Virus Disease outbreaks have occurred in Africa. The 2014-2016 Ebola outbreaks in West Africa began in rural southeast Guinea, and then spread to urban areas and across borders within weeks. Within months Ebola turned into a global epidemic.​​