(1’51秒-2分53秒）A ccording to Bill Gates, the current problems to contaim pandemics include the following EXCEPT

There have been three major pandemics in human history, of which the ( ) is commonly known as the "Black Death". A: Smallpox B: Cholera C: AIDS D: Plague

The flu is a highly (1) respiratory illness. It turns up year after year with devastating consequences, all caused by a most elusive virus. The influenza, or flu virus, is a recurring nightmare. It causes more than 36,000 deaths in the U.S each year, and was responsible for some of history’s deadliest pandemics. Like other viruses, the flu virus is a parasite. The viral agent itself called, a virion, is made of ribonucleic acid or RNA surrounded by proteins. The flu virus uses two proteins to attack its host, hemagglutinin and neuraminidase or the HA and NA proteins. The HA protein attaches a virus to a cell and lets it in. Once the virus is inside, it multiplies. Then the NA protein cuts this (2) swarm loose, sending it off to infect more cells. This triggers the immune system to bombard the swarm and to destroy infected tissue throughout the respiratory system. Unfortunately, this response can also inadvertently lead to death through organ failure or secondary infections like (3) pneumonia. The flu virus has been nearly impossible to eradicate, largely due to its uncanny ability to mutate. Since just 2004, more than 5,000 different strains of the influenza virus have been sequenced. Those that affect humans are categorized as Types A, B or C, with Type A strains being the most capable of unleashing a pandemic. Influenza A viruses mutate more rapidly, allowing them to adapt to new hosts and even cross species. Avian flu and Swine flu, for instance, are two strains of Type A viruses that through mutations, can be transmitted from birds and pigs to humans. One of the deadliest flu (4) was caused by one such virus. Between 1918 and 1919, the Spanish flu infected a third of the global population and killed up to 50 million people worldwide. Called H1N1, this particular strain of virus likely came from birds. The threat of another influenza pandemic remains. In the meantime, scientists are constantly monitoring the flu virus and developing seasonal (5) to create our best line of defense.

Complete the following passage using words from the list A-L in the box below. A. sore B. severe C. connect D. infect E. pandemic F. epidemics G. commonly H. Unfortunately I. initially J. expected K. suspected L. runny Influenza, (1) called "the flu," is an illness caused by RNA viruses (Orthomyxoviridae family) that (2) the respiratory tract of many animals, birds, and humans. In most people, the infection results in the person getting a fever, cough, headache, and malaise (tired, no energy); some people also may develop a (3) throat, nausea, vomiting, and diarrhea. The majority of individuals has flu symptoms for about 1-2 weeks and then recovers with no problems. However, compared with most other viral respiratory infections, such as the common cold, influenza (flu) infection can cause a more (4) illness with a mortality rate (death rate) of about 0.1% of people infected with the virus. The above is the usual situation for the yearly occurring "conventional" or "seasonal" flu strains. However, there are situations in which some flu outbreaks are severe. These severe outbreaks occur when a portion of the human population is exposed to a flu strain against which the population has little or no immunity because the virus has become altered in a significant way. These outbreaks are usually termed (5) . Unusually severe worldwide outbreaks (pandemics) have occurred several times in the last hundred years since influenza virus was identified in 1933. By an examination of preserved tissue, the worst influenza (6) (also termed the Spanish flu or Spanish influenza) occurred in 1918 when the virus caused between 40-100 million deaths worldwide, with a mortality rate estimated to range from 2%-20%. In April 2009, a new influenza strain against which the world population has little or no immunity was isolated from humans in Mexico. It quickly spread throughout the world so fast that the WHO declared this new flu strain (first termed novel H1N1 influenza A swine flu, often later shortened to H1N1 or swine flu) as the cause of a pandemic on June 11, 2009. This was the first declared flu pandemic in 41 years. Fortunately, there was a worldwide response that included vaccine production, good hygiene practices (especially hand washing), and the virus (H1N1) caused far less morbidity and mortality than was (7) and predicted. The WHO declared the pandemic's end on Aug. 10, 2010, because it no longer fit into the WHO's criteria for a pandemic. Researchers identified a new influenza-related viral strain, H3N2, in 2011, but this strain has caused only about 330 infections with one death in the U.S. Since 2003, researchers identified another strain, H5N1, a bird flu virus, that caused about 650 human infections. This virus has not been detected in the U.S. and easily spreads among people in contrast to other flu strains. (8) , people infected with H5N1 have a high death rate (about 60% of infected people die). Currently, H5N1 does not readily transfer from person to person like other flu viruses.