Disaster movies often portray catastrophes that destroy, or at least threaten to destroy earth's entire population. In fact, a virus emerged in the 1970s that could've been just that fatal. Named after a river that passes through the Congo, the Ebola virus originally manifested itself in the interior of Africa in 1976. Two strains of the disease, with almost identical symptoms, affected humans- Ebola-Zaire and Ebola-Sudan. The Sudan version was deadly enough, killing 50% of those it infected. However, Zaire, with its 90% mortality rate, was even worse. The origins, though not the cause of Ebola-Sudan, can be traced back to a single individual in a Sudanese town. Ebola-Zaire seemed to erupt in over 50 villages simultaneously. Both strains quickly invaded local hospitals when needle sharing and other unhealthy practices ensured the rapid spreading of the infection by bringing people into contact with contaminated body fluids. If the virus had been capable of spreading through the air, or if one infected person had unknowingly entered a large population center, Ebola might have become a worldwide epidemic. However, soon after these fierce outbreaks, the virus died out, at least temporarily. Ebola was so deadly and killed so quickly that within a short period of time, there was no one around to infect. Hospital workers in at least one case deserted their workplace in panic, thus halting the administering of potentially unclean disease spreading injections, but Ebola has not disappeared. With no known vaccination or cure available, it seems only a matter of time until another epidemic erupts.
灾难题材的电影通常描绘的是毁灭性的灾难或者是威胁到地球人类生存的因素 。其实，20世纪70年代出现的一种病毒可以说是一次致命的灾难 。以一条流经刚果的河流而命名的埃博拉病毒，最初出现于1976年的非洲 。埃博拉病毒中的埃博拉-扎伊尔型、埃博拉-苏丹型是威胁人类健康的主要两个亚型 。苏丹型的杀伤力惊人，被其感染的只有一半的存活率 。而扎伊尔型的死亡率高达90%%，甚至更高 。苏丹埃博拉病毒最早是在苏丹小镇的一名工人身上发现的 。而扎伊尔埃博拉病毒同时爆发于河沿岸50个村庄 。当地医疗机构不完善的医疗条件如共用注射针头等，使感染者的体液迅速传播，导致埃博拉病毒肆虐整间医院 。假如病毒可通过空气传播，或者不知名的感染者进入人口密集的公众场合，那么，埃博拉病毒很可能会席卷全球 。然而，经过几次肆虐之后，“埃博拉”病毒销声匿迹了，至少暂时被控制住了 。“埃博拉”病毒的传播和致死率如此之高，在短时间内，几乎无人幸免 。医护人员因恐慌而逃离医院的举动，某方面来说也降低了潜在的病毒通过注射蔓延的概率 。若还没有找到任何防治措施的话，下一次的病毒来袭只是时间长短的问题 。
Questions 22 to 25 are based on the passage you have just heard.
Questions 22. What is Ebola virus named after?
Questions 23. What do we learn about Ebola-Zaire and Ebola-Sudan?
Questions 24. How do people get infected with the disease according to the speaker?
Questions 25. What does the speaker believe?