名词解释题大流行（pandemic）

某病发病率水平超过该地一定历史条件下的流行水平，迅速蔓延跨省、国家、洲界（）。

现在比较流行的个性分类是（）。

流感的流行的周期（）

寄生虫病流行的三个环节是（）、（）和（）；影响流行的三大因素是（）、（）和（）。

方病流行特点不包括：（）

简述传染病流行的三大条件。

某病在某地区显著超过该病历年发病率水平

Directions:In this section, there is one passage followed by 5 questions. Read the passage carefully, then answer the questions in as few words as possible (not more than 10 words). Remember to write the answers on the Answer Sheet.　　Questions 1-5 are based on the following passage.　　Many people today are worried about bird flu. They are afraid that it will pass from birds to humans and that thousands of people will die in a pandemic. In 1918 a flu virus killed about 50 million people around the world. The virus was called Spanish influenza (or Spanish flu, for short) because Spanish newspapers first described the disease. Now, after nine years of work, scientists in an American laboratory in Atlanta, Georgia, have produced a copy of the Spanish flu virus. They are also going to publish the genetic sequence of the virus on the Internet and some experts are afraid that other laboratories could copy the virus.　　Scientists have copied the virus because they want to understand why the 1918 Spanish flu pandemic killed so many people. In a report in the journal Science, Dr. Jeffery Taubenberger and a team of scientists in the USA show that the copied virus is extremely powerful. The scientists injected the virus into mice and the mice began to lose weight very quickly. They lost 13% of their weight in two days and all of the mice died within six days.　　“I didn’t expect it to be as lethal as it was,”Dr. Terrence Tumpey, one of the scientists in the team, told the journal Nature. In another experiment, they injected more mice with a normal type of flu. The mice lost weight at first but then they got better and did not die. The experiments showed that the mice with the Spanish flu virus had 39,000 times more flu virus in their bodies than the second group of mice.　　The scientists who copied the virus say their work has already provided important information about the virus and helps to explain why it is so lethal. But other experts are worried that the virus could escape from the laboratory. “Some people will think that they have really created a biological weapon,” said Professor Ronald Atlas of the University of Louisville in Kentucky. “I am even more worried now than I was before about the possibility of a flu pandemic. The 1918 flu pandemic started with bird flu and that might happen again today with Asian bird flu.”　　Some scientists are worried about the publication of the genetic sequence on the Internet. They are afraid that biologists could copy the virus using the information on the Internet. This could be very dangerous.　　It took a long time to copy the virus. Scientists used material taken from the lungs of people who died from the flu virus in 1918. In a second report in Nature, Taubenberger and his colleagues analyzed the genetic make-up of the virus. They were surprised to find that it was completely different from all the normal human flu viruses. This probably means that Spanish flu jumped from birds to humans and did not mix with a human virus first. This is very worrying for scientists because in the past everyone believed that a pandemic was only possible if a bird flu virus mixed with a human flu virus.　　Taubenberger says it is very important to know what changes in the virus caused the 1918 Spanish flu virus. This will help scientists to work out which viruses might cause a pandemic. The H5N1 bird flu in Asia is already changing and it could infect humans, he said.　　Viruses have escaped from high-security labs before. The SARS virus escaped at least twice, once in Taiwan and once in Singapore. But some scientists believe a pandemic will not happen even if the virus escapes, because most people are naturally immune and there are now a lot of drugs which protect people from flu.　　Questions:　　1．When was the Spanish flu pandemic?　　2．How many people died in the Spanish flu pandemic?　　3．Where did the scientists produce a copy of the Spanish flu virus?　　4．How quickly did the laboratory mice die?　　5．What is H5N1?