This is Sarah Long.
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.
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.
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.
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
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.
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
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.
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
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.
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
Hepatitis E was first recognized as a separate disease from
hepatitis A in nineteen-eighty.
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.
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
This SCIENCE IN THE NEWS program was written by Mario Ritter.
It was produced by George Grow. This is Doug Johnson.
And this is Sarah Long. Join us again next week for more news
about science in Special English on the Voice of America.
This Science Report is published courtesy