SCIENCE IN THE NEWS - Polio: How an Ancient Disease Met a Mo

SCIENCE IN THE NEWS - Polio: How an Ancient Disease Met a Modern Prevention
By Jerilyn Watson

Broadcast: Tuesday, April 26, 2005

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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Faith Lapidus.

VOICE TWO:

 
Dr. Jonas Salk(Photo - Yousuf Karsh 1956/National Gallery of Australia)
And I'm Bob Doughty¹. This week, we remember the discovery of the first effective protection against the disease polio. We also talk about the scientists who made it possible.

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VOICE ONE:

Fifty years ago, American media reported a major and welcome announcement. They said scientists had created a medicine to protect people against polio. The medicine was described as safe, powerful and effective. The announcement was made on April twelfth, nineteen fifty-five. The date is now fixed² in medical history.

Today, international efforts have greatly reduced cases of polio around the world. The World Health Organization supports a campaign to end the health threat from the disease by this year. A worldwide effort called the Global Polio Eradication³ Initiative⁴ is working toward this goal.

VOICE TWO:

About three hundred fifty thousand polio cases were reported in one hundred twenty-five countries in nineteen eighty-eight. Since then, the number of cases has been cut by ninety-nine percent.

But some nations have not stopped the spread of the disease. The W-H-O says heavily populated countries like India and Nigeria still report cases. Polio remains⁵ a problem in other countries like Afghanistan, Egypt, Niger and Pakistan.

Doctors say most patients suffer only signs of a cold or mild intestinal⁶ problem. Yet polio has been one of the most frightening diseases in history. People with the most severe cases died, sometimes quickly. Others were left unable to walk or breathe on their own. There was no cure or truly effective treatment.

In recent years, some people who were infected long ago have developed new pain and weakness. The problem is called post-polio syndrome⁷.

VOICE ONE:

Polio was first recorded in ancient Egypt, Greece and Rome. A virus causes the disease. It attacks the muscles and nervous system. The sickness spreads from person to person. It is carried in food, water and human waste.

Scientists first identified the virus in nineteen oh-eight. But they could not stop the sickness from spreading. For example, polio killed six thousand people in the United States in nineteen sixteen. Twenty-seven thousand other Americans suffered permanent damage.

For years, polio remained a health threat. Many victims were children and young adults. Families attempted all kinds of methods to protect their children. But still the sickness kept spreading. This was especially true during hot summers. In the summer of nineteen fifty-two, more than fifty-seven thousand Americans were infected.

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VOICE TWO:

Antibiotic⁸ medicines do not destroy viruses. Only bacteria can be killed that way. Medicines that kill viruses also kill healthy cells. That is why it was necessary for scientists to prevent a viral infection instead of attempting to treat it.

Only three vaccines¹⁰ were used for viral sicknesses until the nineteen forties. A vaccine⁹ works by placing a small amount of weakened virus in the body. This helped the body develop substances in the blood that can destroy the disease if it appears. These substances are called antibodies.

VOICE ONE:

Several research scientists were working to develop a treatment for polio after World War Two. But Jonas Salk wanted to create a protective medicine. He believed a vaccine made from a killed virus could kill the polio virus. However, other researchers said his method would never succeed.

Doctor Salk did not listen. He gathered a team of experts at the University of Pittsburgh School of Medicine in the state of Pennsylvania. They worked to produce a substance that could kill a live poliovirus.

VOICE TWO:

Millions of Americans provided money for the research. Adults and children would give their money to the Infantile Paralysis¹¹ Foundation. Today, the group is called the March of Dimes¹².

President Franklin Delano Roosevelt helped start the Foundation in the late nineteen thirties. Mister Roosevelt became sick with polio when he was thirty-nine years old. He never walked again without help.

The money from Americans helped Doctor Salk's team create antibodies that would kill the virus. In nineteen fifty-two, the team identified three major kinds of polio virus. That meant creating a vaccine that would kill all three. The team also had to discover how to grow the viruses.

VOICE ONE:

In the nineteen thirties, scientists used tissue from the backbones¹³ of monkeys to grow the virus. The tissue was called neural¹⁴ tissue. However, vaccines with the virus grown in neural tissue gave people the disease.

A young man named Julius Youngner worked with Doctor Salk to develop a way to grow the virus in non-neural tissue. Professor Youngner decided¹⁵ to use tissue from the kidneys¹⁶ of monkeys.

He did so by cutting up the outer cover of this organ. At first, it was hard for him to grow the cells. They became thick in test tubes. But then he added a substance called trypsin. The trypsin made the tissue break into separate cells.

Julius Youngner developed ways to grow enough of the virus needed to produce a vaccine. Other scientists say he invented modern cell cultures. But Professor Youngner says the real heroes were the monkeys. Today, he is the only survivor¹⁷ of Doctor Salk's main research team.

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VOICE TWO:

Other researchers did not agree that the killed virus made the most effective vaccine. One of them was Albert Sabin. He disagreed with the way Doctor Salk's team was building antibodies to fight polio. Doctor Sabin wanted to use a weakened live polio virus to build disease antibodies.

Doctor Sabin attempted to prevent the test of the Salk polio vaccine. But the attempt failed. A large trial of the Salk vaccine began in nineteen fifty-four. The results showed that polio rates decreased greatly in people who had been vaccinated¹⁸. The next April, the medicine was declared safe and effective.

VOICE ONE:

The Salk polio vaccine was given with a needle, through the skin. Americans often call such an injection a shot. American parents hurried to get their children protected. Hundreds of thousands of Europeans also got shots. That caused people to say that the Salk vaccine was the shot felt 'round the world.

Now it was time for Doctor Sabin to gain fame in the struggle against polio. In nineteen fifty-seven, he developed a vaccine containing live poliovirus. People could take his oral polio vaccine by mouth. It was easier to protect great numbers of people with the Sabin vaccine than with the Salk vaccine.

VOICE TWO:

One hundred million children in Europe received the Sabin oral polio vaccine in nineteen-sixty. His vaccine was given to one hundred million Americans of all ages from nineteen sixty-two through nineteen sixty-four.

Today, the United States Department of Health and Human Services no longer advises the oral polio vaccine. Instead, officials strongly advise that shots be given to babies and young children. Most adult Americans do not need the vaccine.

This month, the Smithsonian Institution in Washington, D.C., has organized a show called "Whatever Happened to Polio?" The name offers evidence that the disease is rare in much of the world.

VOICE ONE:

Yet polio keeps returning. For example, it disappeared in the western half of the world by the end of the twentieth century. Then, in two thousand one, tests confirmed that several children in the Dominican Republic and Haiti had become infected.

Strong danger from polio still exists in parts of Africa. This month, a coalition¹⁹ of health agencies is working to protect millions of children there. Earlier in the year, United Nations agencies and the Global Polio Eradication Initiative reached up to ninety five million children with the polio vaccine.

VOICE TWO:

An American doctor remembers seeing many children infected with polio at a hospital during the nineteen fifties. Their whole bodies except their heads were inside tanks called iron lungs. The devices helped them to breathe. Some never left the iron lungs.

In the words of the doctor, controlling polio is more than worth the effort.

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VOICE ONE:

This program was written by Jerilyn Watson. Our producer was Cynthia Kirk. I'm Faith Lapidus.

VOICE TWO:

And I'm Bob Doughty. Join us again next week for SCIENCE IN THE NEWS in VOA Special English.

1 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

2 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

3 eradication   

n.根除

参考例句：

• The eradication of an established infestation is not easy. 根除昆虫蔓延是不容易的。
• This is often required for intelligent control and eradication. 这经常需要灵巧的控制与消除。

4 initiative   

n.主动性，首创精神，主动权（的行动），倡议

参考例句：

• He went to see the headmaster on his own initiative.他主动去看望校长。
• His employer had described him as lacking in initiative and drive.雇主说他缺乏进取心和干劲。

5 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

6 intestinal   

adj.肠的；肠壁；肠道细菌

参考例句：

• A few other conditions are in high intestinal obstruction. 其它少数情况是高位肠梗阻。 来自辞典例句
• This complication has occasionally occurred following the use of intestinal antiseptics. 这种并发症偶而发生在使用肠道抗菌剂上。 来自辞典例句

7 syndrome   

n.综合病症；并存特性

参考例句：

• The Institute says that an unidentified virus is to blame for the syndrome. 该研究所表示,引起这种综合症的是一种尚未确认的病毒。
• Results indicated that 11 fetuses had Down syndrome. 结果表明有11个胎儿患有唐氏综合征。

8 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

9 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

10 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

11 paralysis   

n.麻痹(症)；瘫痪(症)

参考例句：

• The paralysis affects his right leg and he can only walk with difficulty.他右腿瘫痪步履维艰。
• The paralysis affects his right leg and he can only walk with difficulty.他右腿瘫痪步履维艰。

12 dimes   

n.（美国、加拿大的）10分铸币( dime的名词复数 )

参考例句：

• Pennies, nickles, dimes and quarters are United States coins. 1分铜币、5分镍币、1角银币和2角5分银币是美国硬币。 来自《简明英汉词典》
• In 1965 the mint stopped putting silver in dimes. 1965年，铸币厂停止向10分硬币中加入银的成分。 来自辞典例句

13 backbones   

n.骨干( backbone的名词复数 )；脊骨；骨气；脊骨状物

参考例句：

• Why do hummingbirds and gorillas both have backbones? 为什么蜂鸟和大猩猩都有脊骨？ 来自辞典例句
• Simply adding bandwidth to the Internet backbones is not an answer. 只是简单的在互联网骨架上增加带宽是应付不了的。 来自互联网

14 neural   

adj.神经的，神经系统的

参考例句：

• The neural network can preferably solve the non- linear problem.利用神经网络建模可以较好地解决非线性问题。
• The information transmission in neural system depends on neurotransmitters.信息传递的神经途径有赖于神经递质。

15 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

16 kidneys   

肾形矿脉； 肾，肾脏( kidney的名词复数 )； （可食用的动物的）腰子

参考例句：

• The function of the kidneys is to excrete wastes from the body. 肾的功能是排泄人体里的废物。
• She got a very dangerous disease of kidneys. 她得了一种很危险的肾病。

17 survivor   

n.生存者，残存者，幸存者

参考例句：

• The sole survivor of the crash was an infant.这次撞车的惟一幸存者是一个婴儿。
• There was only one survivor of the plane crash.这次飞机失事中只有一名幸存者。

18 vaccinated   

[医]已接种的，种痘的，接种过疫菌的

参考例句：

• I was vaccinated against tetanus. 我接种了破伤风疫苗。
• Were you vaccinated against smallpox as a child? 你小时候打过天花疫苗吗？

19 coalition   

n.结合体，同盟，结合，联合

参考例句：

• The several parties formed a coalition.这几个政党组成了政治联盟。
• Coalition forces take great care to avoid civilian casualties.联盟军队竭尽全力避免造成平民伤亡。