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Ⅳ.Background Information 1.Health Officials Struggle to Understand SARS Sever acute respiratory syndrome (SARS) has terrified the world.The question on everybody’s mind is whether SARS will become a global epidemic. Researchers worldwide have galvanized to combat SARS.The challenge for public health is to determine the nature and potential of any viral threat and to frame a battle plan. “We are in an evolutionary stage of this epidemic，”said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda，Maryland. “It could plateau，go up and down，disappear of explode.This virus is highly virulent，potentially lethal and highly transmissible--it has the potential to cause a really bad epidemic.” A Deadly Combination SARS is a so—called hybrid virus—the kind that always triggers a red alert.Traditionally a virus affects a single species.But sometimes two viruses combine their genetic material and form a new virus that“ jumps” to another species altogether. Hybrids are dangerous because the body has never encountered them before，and the immune system is unprepared. “From studying the sequence we see that the SARS virus is derived from a mouse coronavirus and an avian coronavirus，”said Michael Lai，a pioneer in coronavirus genetics at the University of Southern California in Los Angeles. If the virus exists in a wild widespread host--like the West Nile virus carried by mosquitoes—then SARS could be a perennia11y recurring problem, according to Lai. If the host is a domestic animal一like the chicken responsible for the Avian F1u virus of 1997--then the source of the virus could be eliminated.The Avian Flu effectively stopped after the Hong Kong government ordered the slaughter of chickens in the area. Lai suspects that the SARS virus lurks in a wild animals. “It probably doesn’t bother domestic animals or we would have come across it before，”he said. 1f people are the only carriers of SARS，“honest reporting of SARS cases and stringent quarantines could stop the virus in its tracks ,”Lai said. Knowing a Virus，Predicting an Epidemic “Making a vaccine could be quite straightforward，if it is needed。”Lai said. (责任编辑：admin) |