[Science in the News]:Tuberculosis


VOICE ONE:

This is Bob Doughty.

VOICE TWO:

And this is Steve Ember with Science in the News, a VOA SpecialEnglish program about recent developments in Science. Today, we tellabout the disease tuberculosis.

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VOICE ONE:

The World Health Organization says tuberculosis is a serioushealth problem around the world. It says one-third of the world'spopulation is infected with the T-B bacteria. Between five and tenpercent of people who are infected with T-B become sick at some timeduring their life. Eight-million people become sick with the diseaseeach year. Two-million people die of the disease each year.

Tuberculosis is a bacterial infection that usually attacks thelungs. Most people infected with the tuberculosis bacteria neverdevelop active T-B. However, people with weak body defense systemsoften develop the disease. T-B can damage a person's lungs or otherparts of the body and cause serious sickness.

The disease is spread by people who have active, untreated T-Bbacteria in their lungs or throat. The bacteria are spread into theair when people with the disease talk, cough or sneeze.

VOICE TWO:

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

So, the spread of the disease usually does not happen unless aperson spends a great deal of time with a T-B victim. Those most atrisk are family members, friends and people who work closely with aT-B victim. If a person becomes infected with the tuberculosisbacteria, it does not mean he or she has the disease. Having atuberculosis 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 systemusually acts to surround them and prevent them from spreading. Theimmune system does this by building a wall around the bacteriasimilar to the way blood hardens around a cut on the skin. Thebacteria can stay alive in an inactive condition inside these wallsfor many years.

When T-B bacteria are inactive, they cannot damage the body.Also, they cannot spread to other people. People with inactive T-Bbacteria are infected, but they are not sick. They probably do notknow that they infected. Millions of people have the T-B infection.For most of them, the bacteria will always be inactive. They willnever suffer signs of tuberculosis.

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VOICE TWO:

If the body's defense system is weak, however, a person can gettuberculosis soon after the T-B bacteria enter the body. Also,inactive T-B bacteria may become active if the body's immune systembecomes weak. When this happens, the bacteria can break through theprotective walls. Then they begin reproducing and damaging the lungsor other organs. When T-B bacteria become active, they can causeserious sickness.

The inactive T-B bacteria can become active under severalconditions. When a person becomes old, the immune system may becometoo weak to protect against the bacteria. A serious sickness canweaken the immune system enough to free the T-B bacteria. H-I-V, thevirus that causes AIDS, can cause T-B bacteria to become active.Also, doctors warn that people who use many illegal drugs or drinktoo much alcohol have a higher risk of becoming sick from thetuberculosis bacteria.

VOICE ONE:

T-B can attack any part of the body. However, the lungs are themost common target of the bacteria. People with the disease showseveral signs. They have a cough that continues for a long period oftime. People with a more severe case of tuberculosis may cough upblood.

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

One thing that is especially dangerous about T-B is that peoplewith moderate signs of the disease may not know they have it. Theymay spread the disease to others without even knowing it. So, it isvery important for people to get tested for tuberculosis.

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VOICE TWO:

There are several ways to test for T-B. The first is the Mantouxskin test. The test can identify most people infected withtuberculosis six to eight weeks after the bacteria entered theirbodies. A substance called purified protein derivative is injectedunder the skin of the arm. The place of the injection is examinedtwo to three days later.

If a raised red area forms, the person may have been infectedwith the tuberculosis bacteria. However, this does not always meanthe 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 activeT-B. However, this sometimes can be difficult because tuberculosismay appear similar to other diseases. Doctors must consider otherphysical signs. Also, they must decide if a person's history showsthat he or she has been in situations where tuberculosis waspresent.

Doctors also use an X-ray examination to show if there isevidence of T-B infection, such as damage to the lungs. Another wayto test for the presence of active tuberculosis is to examine thefluids 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 T-Bbacteria are present so they can decide which drugs to use to treatthe disease. More than ninety percent of T-B cases can be cured withmedicines. However, the death rate for untreated T-B patients isbetween forty and sixty percent.

Successful treatment of T-B requires close cooperation amongpatients, doctors and other health care workers.

It is very important for patients to be educated about thedisease and its treatment. Patients must take medicine for six totwelve months to destroy all signs of the bacteria. Sometimespatients fail to finish taking the medicine ordered by theirdoctors. Experts say this is because some patients feel better afteronly two to four weeks of treatment and stop taking their medicine.

This can lead to the T-B bacteria becoming resistant to drugs andgrowing stronger, more dangerous and more difficult to treat.Because of this, many doctors and other health care workers directlyobserve and supervise 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 infectedpeople 鈥?especially those who have the highest risk of developingthe disease. There are several drugs that can prevent tuberculosisin people who are at risk of becoming infected.

These people include those who live or work closely with peoplewho have T-B. Others at risk are people who are infected with thetuberculosis bacteria but do not have the active disease.

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 whenthey cough or sneeze. It also is important to keep air flowingthrough rooms so that the T-B bacteria cannot gather and infectpeople. Also, ultraviolet light and other devices can be used toclean infectious bacteria from the air in closed rooms.

Tuberculosis can be cured if it is discovered early and ifpatients take their medicine correctly. And, like other diseases,education and understanding are extremely important in preventingand curing T-B.

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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 newsabout science in Special English on the Voice of America.

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