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VOICE ONE:
This is Sarah Long.
VOICE TWO:
And this is Doug Johnson with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about five forms of hepatitis, a viral disease that attacks the liver.
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VOICE ONE:
Very different viruses that spread through body waste or body fluids cause hepatitis. Different kinds of hepatitis can only be identified by tests that show infection-fighting molecules, called antibodies, in the blood. All hepatitis viruses attack and destroy liver cells.
At one time, only developing nations suffered severe health problems caused by the hepatitis viruses. Today, scientists have identified five viruses that cause hepatitis. These viral diseases have become a major health problem for all nations and social groups.
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Hepatitis A is a virus that infects people who come in contact with waste from an infected person. It is usually spread through human waste in food or water. It is believed to be one of the oldest known diseases. It is in the same group of viruses that causes polio. The hepatitis A virus causes fever, tiredness, and pain. It also causes problems with the stomach and intestines making it difficult to eat or process food. The skin of a person infected with hepatitis A may turn yellow because the person’s liver does not work normally.
Hepatitis A can spread quickly, affecting tens of thousands of people. However, the disease is deadly in less than one percent of cases. Many people can have the antibodies to this disease and yet never become sick from it. In the United States, hepatitis A is decreasing because of preventive measures. There is a vaccine medicine that can prevent the disease. Some states require that children be vaccinated for the disease.
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The second form of the disease is hepatitis B. This virus is more dangerous than virus A. Hepatitis B is one of a group of viruses that include herpes and smallpox. The hepatitis B virus also has been linked to liver cancer. For this reason, the World Health Organization considers the hepatitis B vaccine to be the first vaccine against a cancer in humans.
Hepatitis B is spread when blood or body fluids of an infected person enter the body of another person. The disease can spread quickly through sex. It also can spread among people who share needles to inject drugs into the blood. It also can be transferred through blood products. It can even be spread through fluids from the nose or mouth.
In the United States, children are now vaccinated against hepatitis B at an early age. This has helped to control the spread of the disease in this country. Around the world, however, three-hundred-fifty-million people are believed to be severely infected with the hepatitis B virus. About one-million people die from the disease every year.
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A third form of hepatitis is even more deadly. Hepatitis C belongs to a group of viruses that includes yellow fever and West Nile virus. It is spread mainly by direct contact with infected human blood. Health experts say the main causes of infection have been infected blood given to patients during operations and medical needles that have not been cleaned correctly. People who share needles used to inject drugs into the blood can infect each other. The disease is also spread through sex.
Hepatitis C is dangerous because about eighty percent of those who become infected with the virus develop a severe form of the disease. More than ten percent of those who show effects of the disease develop severe liver damage. As many as five percent of those people develop liver cancer.
VOICE ONE:
There is no vaccine to prevent hepatitis C. Several blood tests can show if the virus is present. Hepatitis C has become a major problem in industrial and developing countries. The World Health Organization estimates that about one-hundred-seventy-million people are infected around the world. The highest infection rates are in Africa, the eastern Mediterranean and the western Pacific.
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In the United States, hepatitis C remains a great concern. Last year, the National Institutes of Health reported on developments in the treatment of the C virus. The report found that at least four-million Americans have the disease.
Hepatitis C was first observed in nineteen-seventy-four. At the time it was considered an unusual kind of hepatitis. The disease was not officially recognized until nineteen-eighty-nine.
The spread of the disease was largely brought under control by nineteen-ninety-two because of medical testing of blood and tissue products. Until that time, many people became infected when they received some kinds of blood products.
VOICE ONE:
The N-I-H study discovered high numbers of infected people in some groups, including homeless people and prisoners. Between fifteen and fifty percent of the people in these groups are believed to be infected.
People who inject illegal drugs are another high-risk group. So are people with the blood disease hemophilia who received blood products before nineteen-ninety-two. These groups have the highest percentage of infected people. Death documents suggest that as many as twelve-thousand people die of hepatitis C every year in America.
The N-I-H report states that treatment with two drugs used together appears to help infected patients. The drugs are ribavirin and interferon. Interferon is also known to fight some cancers. However, interferon and ribavirin are costly and require careful medical support.
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Two other forms of hepatitis viruses have been linked to liver disease. Hepatitis D can only infect people who have already been infected with hepatitis B. It also spreads in the same way as hepatitis B. The hepatitis D virus greatly increases the chance of severe liver damage.
The World Health Organization says that ten-million people around the world are infected with hepatitis D. The organization says the disease is spreading in places where hepatitis B is present. However, medical scientists have not done much research on the virus because it has been identified only recently.
VOICE ONE:
The fifth kind of virus is hepatitis E. It is spread in the same way as hepatitis A -- through contact with infected human waste. This often happens when human waste pollutes water supplies. In developing countries, outbreaks of hepatitis caused by infected water are now suspected to be hepatitis E rather than hepatitis A.
Hepatitis E was first recognized as a separate disease from hepatitis A in nineteen-eighty.
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Studies have shown that the E virus shares qualities of several very different viruses. It can also infect many kinds of animals including pigs, cows and monkeys. It is possible that the disease can be spread from animals to humans.
There is no vaccine for hepatitis E. No medicine currently exists to treat the disease. Hepatitis E can cause liver damage like the other forms of hepatitis. It may cause death in up to four percent of severe cases. However, it is very dangerous for pregnant women. The death rate among pregnant women is twenty percent. Hepatitis E is not known in the United States. But it has caused outbreaks in Asia, Africa, and Mexico.
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There is no cure for any form of hepatitis. Vaccination can greatly reduce the risk of severe infection from the A and B virus. The only way to protect against infection is to avoid contact with the viruses. Experts say people should avoid any kind of injection with dirty needles or medical instruments. They should also avoid sexual contact with people who may be at risk. Food and water supplies should be protected from pollution by human waste.
Also, blood supplies must be tested for the viruses. People who are in high-risk groups or who have had the disease should not give blood or blood products. Experts say careful preventive measures are the only way to control the spread of the hepatitis viruses.
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VOICE TWO:
This SCIENCE IN THE NEWS program was written by Mario Ritter. It was produced by George Grow. This is Doug Johnson.
VOICE ONE:
And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.