SCIENCE IN THE NEWS - Successes Against Tuberculosis, But No

SCIENCE IN THE NEWS - Successes Against Tuberculosis¹, But Not Everywhere
By George Grow

Broadcast: Tuesday, July 19, 2005

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VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty².

VOICE TWO:

And I'm Barbara Klein. On our program this week, we tell about the disease tuberculosis. Tuberculosis can be deadly if not treated the right way. It is a serous health problem around the world.

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VOICE ONE:

The World Health Organization says one-third of the world's population is infected with the TB bacteria. Between five and ten percent of those infected become sick with tuberculosis at some time during their life. Almost nine million people become sick with the disease each year. More than one million seven hundred thousand people die of the disease each year.

In March, the W.H.O. reported that the war against TB is being successfully fought in many areas. It said the number of TB cases worldwide has dropped twenty percent since nineteen ninety. It also said infection rates are now falling or unchanged in five of six areas around the world.

The exception is Africa. The W.H.O. said TB rates in Africa are still rising at a rate of three to four percent each year. TB rates there have risen two hundred percent since nineteen ninety in areas where many people have the virus that causes AIDS.

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VOICE TWO:

Tuberculosis is a bacterial³ infection that usually attacks the lungs. Most people infected with the bacteria never develop active TB. However, people with weak body defense⁴ systems often develop the disease. TB can damage a person's lungs or other parts of the body and cause serious sickness.

The disease is spread by people who have active, untreated TB bacteria in their throat or lungs. The bacteria are spread into the air when people with the disease talk, cough or sneeze or expel⁵ air suddenly.

People who breathe infected air from a TB victim can become infected with the tuberculosis bacteria. However, most people with active tuberculosis do not expel very many TB bacteria.

So, the spread of the disease usually does not happen unless a person spends a great deal of time with a TB victim. Those most at risk are family members, friends and people who work closely with a TB victim. If a person becomes infected with the TB bacteria, it does not mean he or she has the disease. Having the infection means that the bacteria are in the body, but they may be neutral, or inactive.

VOICE ONE:

After the TB bacteria enter the body, the body's defense system against disease usually acts to surround the bacteria and prevent them from spreading. The immune⁶ system does this by building a wall around the bacteria similar to the way blood hardens around a cut on the skin. The bacteria can stay alive in an inactive condition inside these walls for many years.

When TB bacteria are inactive, they cannot damage the body. And they cannot spread to other people. People with the inactive bacteria are infected, but they are not sick. They probably do not know that they are infected. Millions of people have the TB infection. For most of them, the bacteria will always be inactive. They will never suffer signs of tuberculosis.

VOICE TWO:

 
 
If the body's immune system is weak, however, a person can get tuberculosis soon after the TB bacteria enter the body. Also, inactive TB bacteria may become active if the immune system becomes weak. When this happens, the bacteria can break through the protective walls. Then, they begin reproducing⁷ and damaging the lungs or other organs. When TB bacteria become active, they can cause serious sickness.

The inactive TB bacteria can become active under several conditions. When a person becomes old, the immune system may become too weak to protect against the bacteria. A serious sickness can weaken the immune system enough to free the TB bacteria. H.I.V., the virus that causes AIDS, can cause TB bacteria to become active. Also, doctors warn that people who drink too much alcohol or use illegal drugs have a higher risk of becoming sick from the tuberculosis bacteria.

VOICE ONE:

TB can attack any part of the body. However, the lungs are the most common targets of the bacteria. People with the disease show several signs. They expel air from the lungs suddenly with an explosive noise, or cough. This cough continues for a long period of time. People with a more severe case of tuberculosis also may cough up blood.

People with the disease often have high body temperatures. They suffer what are called night sweats, during which their bodies give off large amounts of water through the skin. TB victims also are tired all the time. They are not interested in eating. So they lose weight.

One thing that is especially dangerous about TB is that people with moderate signs of the disease may not know they have it. They may spread the disease to others without even knowing it. So, it is very important for people to get tested for tuberculosis.

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VOICE TWO:

There are several ways to test for TB. The first is the TB skin test. It also is known as the Mantoux (MAN-two) skin test. The test can identify most people infected with tuberculosis six to eight weeks after the bacteria entered their bodies. A substance called purified⁸ protein derivative⁹ is injected under the skin of the arm. The place of the injection is examined two to three days later.

If a raised red area forms, the person may have been infected with the tuberculosis bacteria. However, this does not always mean the disease is active.

VOICE ONE:

If the skin test shows that TB bacteria have entered the body, doctors can use other methods to discover if the person has active T-B. However, this sometimes can be difficult because tuberculosis may appear similar to other diseases. Doctors must consider other physical signs. Also, they must decide if a person's history shows that he or she has been in situations where tuberculosis was present.

Doctors also use an X-ray examination to show if there is evidence of TB infection, such as damage to the lungs. Another way to test for the presence of active tuberculosis is to examine the fluids from a person's body, especially those taken from the mouth.

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VOICE TWO:

It is very important for doctors to identify which kind of TB bacteria are present so they can decide which drugs to use to treat the disease. More than ninety percent of TB cases can be cured with medicines. However, the death rate for untreated patients is reported to be about fifty percent. Successful treatment of TB requires close cooperation among patients, doctors and other health care workers.

It is very important for patients to be educated about the disease and its treatment. Patients must take medicine for six to twelve months to destroy all signs of the bacteria. Sometimes patients fail to finish taking the medicine ordered by their doctors. Experts say this is because some patients feel better after only two to four weeks of treatment and stop taking their medicine.

This can lead to the TB bacteria becoming resistant¹⁰ to drugs and growing stronger, more dangerous and more difficult to treat. Because of this, many doctors and other health care workers directly observe and supervise¹¹ treatment of the disease in their patients.

VOICE ONE:

Experts say TB is a preventable disease. In the United States, the goal of health organizations is to quickly identify infected people – especially those who have the highest risk of developing the disease. There are several drugs that can prevent tuberculosis in people who are at risk of becoming infected. These people include those who live or work closely with people who have TB. Others at risk are people who are infected with tuberculosis bacteria but do not have the active disease.

VOICE TWO:

There are a number of ways to limit the spread of tuberculosis. All TB patients must learn to cover their mouths and noses when they cough or sneeze. It also is important to keep air flowing through rooms so that the TB bacteria cannot gather and infect people. Also, ultraviolet¹² light and other devices can be used to clean infectious¹³ bacteria from the air in closed rooms.

Experts say tuberculosis can be cured if it is discovered early and if patients take their medicine correctly. And, like other diseases, education and understanding are extremely important in preventing and treating TB.

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VOICE ONE:

This SCIENCE IN THE NEWS program was written by George Grow. Cynthia Kirk was our producer. I'm Bob Doughty.

VOICE TWO:

And I'm Barbara Klein. Join us again next week for more news about science in Special English on the Voice of America.

1 tuberculosis   

n.结核病，肺结核

参考例句：

• People used to go to special health spring to recover from tuberculosis.人们常去温泉疗养胜地治疗肺结核。
• Tuberculosis is a curable disease.肺结核是一种可治愈的病。

2 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。

3 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

4 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

5 expel   

vt.把...开除，驱逐，放逐，排出，喷出

参考例句：

• They were told at first that they should simply expel the refugees.一开始有人告诉他们应该直接将那些难民驱逐出境。
• The headmaster may expel the boy from the school.校长可能要把那个男孩从学校开除。

6 immune   

adj.免疫的，有免疫力的，不受影响的，免除的

参考例句：

• I am immune from the disease,for I had it once.我对这病有免疫力，因为我已得过一次了。
• Be immune from corruption.拒腐蚀，永不沾。

7 reproducing   

复制( reproduce的现在分词 )； 重现； 再版； 生殖

参考例句：

• Mind has become self-reproducing through man's capacity to transmit experience and its products cumulatively. 通过传递生活经验和积累创造的产品，人类的智慧在不断地进行着自我丰富。
• Spores form a lipid membrane during the process of reproducing. 孢于在生殖过程中形成类脂膜。 来自英汉非文学 - 生命科学 - 预防生物武器

8 purified   

adj.纯净的

参考例句：

• The air in the room was purified. 房间的空气得到了净化。
• Water can be purified by filtration through sand. 水通过沙滤可以变清。

9 derivative   

n.派(衍)生物；adj.非独创性的，模仿他人的

参考例句：

• His paintings are really quite derivative.他的画实在没有创意。
• Derivative works are far more complicated.派生作品更加复杂。

10 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。

11 supervise   

v.监督，管理，指导

参考例句：

• We must supervise and speed up the fulfilment of assigned tasks.已经布置了的工作，应当认真督促检查。
• Tomorrow he will supervise all the pupils taking the English examination.明天全体学生考英语，他将担任监考。

12 ultraviolet   

adj.紫外线的；n.紫外线

参考例句：

• It's called ultraviolet rays.它被叫做紫外线。
• The sun's ultraviolet rays are responsible for both tanning and burning.阳光中的紫外线是皮肤晒黑和灼伤的根源。

13 infectious   

adj.传染的，有传染性的，有感染力的

参考例句：

• Influenza is an infectious disease.流感是一种传染病。
• What an infectious laugh she has!她的笑声多么具有感染力啊！