SCIENCE IN THE NEWS - Tuberculosis

（单词翻译）

SCIENCE IN THE NEWS -July 9, 2002: Tuberculosis¹

By Oliver Chanler
VOICE ONE:
This is Bob Doughty².
VOICE TWO:
And this is Steve Ember with Science in the News, a VOA Special English program about recent developments

in Science. Today, we tell about the disease tuberculosis.
((THEME)
)
VOICE ONE:
The World Health Organization says tuberculosis is a serious health problem around the world. It says one-third

of the world’s population is infected with the T-B bacteria. Between five and ten percent of people who are

infected with T-B become sick at some time during their life. Eight-million people become sick with the disease

each year. Two-million people die of the disease each year.
Tuberculosis is a bacterial³ infection that usually attacks the lungs. Most people infected with the tuberculosis
bacteria never develop active T-B. However, people with weak body defense⁴ systems often develop the disease.
T-B 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 T-B bacteria in their lungs or
throat. The bacteria are spread into the air when people with the disease talk, cough or
sneeze.

VOICE TWO:

People who breathe the infected air from a T-B victim can become infected with the
tuberculosis bacteria. However, most people with active tuberculosis do not expel⁵ very
many T-B bacteria.

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

VOICE ONE:

After the T-B bacteria enter the body, the body’s defense system usually acts to surround them 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 T-B bacteria are inactive, they cannot damage the body. Also, they cannot spread to other people. People
with inactive T-B bacteria are infected, but they are not sick. They probably do not know that they are infected.
Millions of people have the T-B infection. For most of them, the bacteria will always be inactive. They will never
suffer signs of tuberculosis.

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)

VOICE TWO:


If the body ’s defense system is weak, however, a person can get tuberculosis soon after the T-B bacteria enter
the body. Also, inactive T-B bacteria may become active if the body’s 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 T-B bacteria become active, they can cause serious sickness.

The inactive T-B 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 T-B bacteria. H-I-V, the virus that causes AIDS, can cause T-B bacteria to become active.
Also, doctors warn that people who use many illegal drugs or drink too much alcohol have a higher risk of
becoming sick from the tuberculosis bacteria.

VOICE ONE:

T-B can attack any part of the body. However, the lungs are the most common target of the bacteria. People with
the disease show several signs. They have a cough that continues for a long period of time. People with a more
severe case of tuberculosis may cough up blood.

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

One thing that is especially dangerous about T-B 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.

((MUSIC BRIDGE))

VOICE TWO:

There are several ways to test for T-B. The first is the Mantoux 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 T-B 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 T-B 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.

((MUSIC BRIDGE))

VOICE TWO:

It is very important for doctors to identify which kind of T-B bacteria are present so they can decide which drugs
to use to treat the disease. More than ninety percent of T-B cases can be cured with medicines. However, the
death rate for untreated T-B patients is between forty and sixty percent.

Successful treatment of T-B 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 T-B 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 T-B 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.

A patient takes his

daily medicine, as
These people include those who live or work closely with people who have T-B. Others at a health worker
risk are people who are infected with tuberculosis bacteria but do not have the active disease. watches.

(WHO photo TDR/
Crump)

VOICE TWO:

There are a number of ways to limit the spread of tuberculosis. All T-B 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 T-B
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.

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 curing T-B.

((THEME))

VOICE ONE:

This SCIENCE IN THE NEWS program was written by Oliver Chanler. It was produced by George Grow. This
is Bob Doughty.

VOICE TWO:

And this is Steve Ember. Join us again next week for more news about science in Special English on the Voice of
America.

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