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Coming Soon: the Next Great Flu FpidemicThe virus first came to

游客2024-01-03  9
问题                 Coming Soon: the Next Great Flu Fpidemic
The virus first came to officials’ attention in a bag of dead chickens. Early in March 1997, a farmer from Hong Kong’s New Territories carried them into the Agriculture and Fisheries Department laboratory. The final state of some birds was a hideous, bloody mush. Cultures of their organs revealed they had died of avian influenza, type H5N1. Influenza of the H5 subtype had never been known to infect humans. But in the next seven months, 18 Hong Kong residents fell ill with H5N1 and six died.
    In late December 1997, public health officials took a drastic step, ordering the slaughter of every chicken in every farm and marketplace in Hong Kong. The H5N1 virus seemed to disappear-but for how long?
    The specter of the 1918 flu was raised by this new avian flu. The 1918 flu was one of the most changeable and resistant viruses known to man. After we’ve been infected with one strain, it can mutate and infect us again. We are only immune to flu strains our bodies have seen before.
    A flu can also "jump species" to an animal it has never infected before, once such a flu moves into humans, if it can "learn" to pass easily between them, it can spark a pandemic -a global outbreak.
    Birds carry the flu virus in their intestines and excrete it in their feces. In all likelihood, shoppers who got sick with H5 touched surfaces contaminated with chicken feces. Humans, however, carry flu in their respiratory tracts and usually spread them in a cough or sneeze. Flu strains that travel this way are highly contagious.
    The H5 virus in Hong Kong was different. It sickened very few, but killed a third of those infected. Most who got sick with H5 seemed to catch it directly from a bird they bought in a live-poultry market.
    After the Hong Kong outbreak, flu experts feared that H5--already deadly to humans—might learn to move between humans as well as between birds. That "raises the specter of 1918", says Nancy Cox, chief of the Influenza Branch of the U. S. Centers for Disease Control and Prevention(CDCP).
    Geographic isolation was no protection during the 1918 pandemic. In the Alaska Territory, the mortality rate in some villages was as high as 90 percent. All told, at least 500 000 Americans perished. It could happen again.
    The virus that became the Spanish flu probably came from a bird. Avian-flu expert Dr. Robert Webster of St. Jude Children’s Research Hospital in Memphis, Tenn. , believes the virus may have leapt straight from birds to humans, possibly a year to two before the pandemic began. Once lodged in human lungs, it quickly passed from person to person in a simple cough or sneeze. To avoid that grim possibility, here are three measures all nations need to take:
    The first step is better surveillance. Most countries, though, don’t start tracking avian flu until after an epidemic kills their chickens. The United States dramatically increased its monitoring after a deadly outbreak in Pennsylvania in the early 1980s. The USDA(United States Department of Agriculture)provides diagnostic support. Some virologists recommend enhancing surveillance of swine flu too. The U. S. National Institutes of Health is beginning to study the issue.
    Elsewhere, the coverage is not good enough, says Dr. W. Paul Glezen of the Baylor College of Medicine’s Influenza Research Center. He names Africa and South America as areas where the World Health Organizations net is incomplete.
    Another important measure is producing more vaccines and flu shots. Only three of the 15 known influenza subtypes—H1, H2 and H3—have been found in people. Vaccines exist for each, and an H5 vaccine is now being developed. Some experts believe that we should develop a vaccine for the other known subtypes as well.
    Health authorities add that more people need flu shots now. We should manufacture 120 million doses a year, but we are making only 80 million. If we bought more vaccines, manufacturers could produce more. This increased production capacity would be invaluable in a pandemic.
    A strong pandemic plan. The U. S. government has been developing a pandemic plan since 1997. The Hong Kong outbreak, notes CDCP investigator Keiji Fukuda, was a "dry run" for a real emergency. "It showed us we can get people there and answer some tough questions," but "H5 also taught us that lots of issues are hard to grapple with because they come so fast".
    In March of this year, Hong Kong’s Agriculture and Fisheries Department announced it had found H5N1 in the goose excrement of a poultry stall.(A)The virus was not identical to the 1997 version, and the next day it was gone.(B)However, the two viruses were related.(C)A month later, in April, the Hong Kong Department of Health announced that two girls, ages one and four, were recovering from an H9 flu virus found in poultry.(D)H9 has never before been known to infect humans. [br] According to the passage, the flu is one of the most changeable viruses known to man because______.
选项 A、it occurs over and over again
B、it changes whenever it jumps species
C、it is so catastrophic that it causes death
D、it is mysterious and difficult to detect
答案 B
解析 本题还是事实信息题。题目问：根据文章内容，流感病毒被认为是最容易发生变异的病毒之一，其原因是下列哪一选项?根据第三段、第四段可以判断，这是因为只要病菌在生物中传播(jump species)，它就不稳定，会发生变异，因为每个生物体的自身条件都是不一样的。因此选择B。选项A(因为它不断出现)、选项C(因为它的杀伤力大，所以致命)和选项D(因为这种病菌很神秘，难以控制)均不符合文章的内容。
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