環(huán)球英語(yǔ) 1279 The History of Vaccines
Welcome to Spotlight. I’m Nick Page.
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And I’m Liz Waid. Spotlight uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live.
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Through history, a deadly disease called “smallpox” threatened people all over the world. In some areas this disease killed more than 10% of the population. And for children it was even worse. Smallpox killed as many as one in every three children. There was no cure. But then, on May 14th, 1796, one simple experiment changed the future of smallpox. The end of smallpox had begun.
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The story of smallpox is linked very closely to the story of vaccines, a kind of medical treatment that people still use today. Today’s Spotlight is on the history of vaccines.
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Smallpox is a very ancient disease. Scientists have found evidence that smallpox has been on the earth for thousands of years.
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Smallpox is a deadly disease. It spreads very easily. The first signs of the disease begin two to four days after infection. There is a very high fever. A person will begin to show a rash - this is raised red bumps on a person’s skin. These bumps are filled with infected liquid. After a time the bumps begin to dry and form skin over them - scabs. Some people do survive after having smallpox. But they often carry terrible permanent scars, or become blind. Many people do not survive.
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Long ago some doctors observed a very interesting thing about this deadly disease. If a person recovered from smallpox he would never get it again. This information led these doctors to try and prevent smallpox in very strange ways.
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Chinese doctors used a method called variolation to prevent people from getting smallpox. They used some of the infected liquids and scabs from people with smallpox. Healthy people breathed in these substances. The doctors hoped people would get a weaker form of smallpox. Then they would recover. If a person recovered the doctors released them. The person would never have a problem with smallpox again.
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No one understood exactly how or why this process worked. And the process was not very safe. Many people who were purposely infected with smallpox died. There was no exact way to control the effects of the disease. But many people did recover. So, doctors considered this method successful. When doctors used this method, fewer and fewer people died from smallpox. Doctors used this process for many years all around the world.
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But one doctor, Edward Jenner, had a different idea about preventing smallpox. Doctor Jenner lived in England. He worked as a doctor in the country. One day a young girl who worked with cows came to him. She had red bumps on her hands. Doctor Jenner identified the bumps as cowpox. The girl said one of her cows had cowpox.
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Cowpox is a very similar disease to smallpox. But it is much less severe. People with cowpox usually only develop a few red bumps on their hands. They feel sick for a short time. But cowpox does not usually cause death. And it is more common in cows than people.
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Doctor Jenner had heard many people in his village say that if a person got cowpox he would be immune to smallpox. He would never become infected with smallpox, a much worse disease. Doctor Jenner saw the chance to perform a very important experiment.
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Doctor Jenner understood that cows could pass cowpox to people. But he wanted to know if people could pass cowpox to other people. So, Doctor Jenner took some liquid from the girl’s cowpox infection. He infected a healthy boy with this liquid. The boy had never had cowpox or smallpox. The boy became sick from the girl’s cowpox. So, now Doctor Jenner knew that a person could pass cowpox to another person.
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After the boy recovered Doctor Jenner wanted to know one more piece of information. He needed to know if the boy was now really immune to smallpox. So, Doctor Jenner injected the smallpox virus into the boy.
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Doctor Jenner was very happy when the boy did not become infected with the smallpox virus! Doctor Jenner tried to infect the boy with smallpox a few more times. But the boy remained healthy. Now Doctor Jenner knew that there was a safer way to stop people from getting smallpox.
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Today no good doctor would perform this experiment. Scientists believe that performing these kinds of experiments on humans is not moral. But back in 1796 this experiment was an important move in producing vaccines.
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Doctor Jenner named his method vaccination. Vaccination is the process of placing particular infected material, like the infected cowpox liquid, under a person’s skin to help protect a body against diseases.
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Doctor Jenner continued studying the link between cowpox and smallpox. For many years people were frightened of his new method. But after a time, people all across the world began to accept Doctor Jenner’s vaccination process. And in England, by 1853, all English people were required to be vaccinated by Doctor Jenner’s method.
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Today people use vaccines everywhere in the world. Vaccines keep many people healthy. Doctor Jenner’s ideas and research have affected people for all time.
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In the year 1801 Doctor Jenner dreamed of ending the smallpox virus forever. He dreamed of making it disappear. In 1967 the World Health Organization, the WHO, shared that dream. In that year they set out to get rid of smallpox. Teams of doctors travelled to areas with a high risk of smallpox. They vaccinated many people.
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Finally, in 1977 Doctor Jenner’s dream came true. Doctors identified the last natural case of smallpox. The man recovered. And since then no other natural case of smallpox has been found anywhere in the world.
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Vaccines have changed since Doctor Jenner’s time. Doctors understand more about infections, staying clean, and how the body works. Doctors have developed vaccines for many diseases that used to be a big problem. People are vaccinated against polio, typhoid, mumps, measles, rubella and many other sicknesses.
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Today many governments require their people to be vaccinated. The WHO works hard to vaccinate people in every country. They even vaccinate people who do not have enough money to pay for medical treatments. The WHO wants to make horrible diseases disappear completely.
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In 1988 the World Health Assembly declared that polio was its next target. It wants to make polio disappear. They have not achieved their goal yet. But vaccines will continue to change the world.
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The writer and producer of this program was Liz Waid. The voices you heard were from the United States and the United Kingdom. Listen for more Spotlight programs about vaccines. You can find our programs on the internet at www.radioenglish.net. This program is called “The History of Vaccines”.
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We hope you can join us again for the next Spotlight program. Goodbye.
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