SCIENCE IN THE NEWS in VOA Special English.
I'm Steve Ember.
I'm Shirley Griffith. This week, we
will tell about six diseases of the liver.
The six diseases come from six different viruses. Doctors have one name for all of them:
liver is in the upper right part of the stomach. This dark, red organ is big.
It weighs more than one kilogram.
And, it has a big job. The liver
helps clean the blood and fight infection.
It also helps break down food and store energy until the body needs it.
destroys liver cells. Some kinds of
hepatitis are much more serious than others.
Scientists have identified the six kinds of hepatitis with the letters
A, B, C, D, E and G. Which kind a
person has can only be known from tests for antibodies in the blood.
are special proteins that the body's natural defenses against disease produce
in answer to a threat. Identify the
antibody and you identify the threat.
A is usually spread through human waste in water or food. It is in the same group of viruses as those
that cause the disease polio.
hepatitis A virus causes high body temperature, weakness and pain. It causes problems with the stomach and
intestines, making it difficult to eat or break down food. Also, the skin of a person with hepatitis
may become yellow. This is a sign that
the liver is not operating normally.
To help prevent the spread of hepatitis
A, people should wash their hands after they use the restroom or change a
baby's diaper. People should also wash
their hands before they eat or prepare food.
Hepatitis A can spread quickly to
hundreds or thousands of people. But
the virus is deadly in less than one percent of cases. Many people infected with the virus never
even get sick. But those who do
generally recover within two months.
World Health Organization says hepatitis A is often found in Africa, Asia and
Central and South America. People who
have had hepatitis A cannot get it again.
There is a vaccine to prevent hepatitis A. America's Centers for Disease Control says the vaccine is the
best way to protect against the disease.
World Health Organization says as many as two billion people are infected with
the hepatitis B virus. More than three
hundred fifty million of those infected have lifelong infections. W.H.O. officials say an estimated six
hundred thousand people die each year as a result of hepatitis B.
virus is in the same group as the herpes and smallpox viruses. Hepatitis B vaccines have been given since
the nineteen eighties. The W.H.O. says
the vaccine is ninety five percent effective in preventing the development of
infection in both children and adults.
B spreads when blood from an infected person enters the body of another
person. An infected mother can infect
her baby. The virus can also spread
through sexual activity, and if people share injection devices.
Blood products from an infected person
can spread hepatitis B. People also can
get infected if they share personal-care products that might have blood on
them. Examples include toothbrushes and
most hepatitis B infections are found in children. Young children are the ones most likely to develop a lifelong, or
chronic, infection. The risk of such an
infection is small for children older than four years.
ninety percent of babies infected with hepatitis B during the first year
develop chronic infections. Such
persons are at high risk of death from liver disease or liver cancer. The hepatitis B vaccine is considered to be
the first medicine that can protect people against liver cancer.
C is even more dangerous. Like
hepatitis B, it spreads when blood from an infected person enters someone who
is not infected.
hepatitis C virus belongs to the same group of viruses as yellow fever and West
Nile virus. Most people living with
hepatitis C develop chronic infections, often without any signs. They are at high risk for liver disease and
Health Organization says about one hundred seventy million people are infected
with hepatitis C. That is three percent
of the population of the world! The
W.H.O. also says that as many as four million more become infected each
year. It warns that those infected may
develop diseases of the liver, including liver cancer. The W.H.O. says the highest rates of
infection are in Africa, Asia, and Central and South America.
have been working to develop a vaccine against hepatitis C. The virus was first observed in nineteen
seventy-four. But it was not officially
recognized as a new kind of hepatitis until nineteen eighty-nine.
The Centers for Disease Control says
about three million Americans are infected with hepatitis C. It says that those especially at risk
include persons who inject themselves with drugs and those who received blood
or blood products before nineteen ninety.
D is spread through blood, but only infects people who already have hepatitis
B. The hepatitis D virus greatly
increases the chance of severe liver damage.
Experts say the virus infects about fifteen million people around the
world. They say it also appears in five
percent of persons infected with hepatitis B.
Doctors say the best way to prevent
hepatitis D is to get vaccine that protects against hepatitis B. Doctors can treat some cases of hepatitis B,
C and D. The drugs used are costly,
however. But they are less costly than
another treatment: getting a new liver.
fifth virus is hepatitis E. Experts say
it spreads the same way as hepatitis A -- through infectious waste. Cases often result from polluted supplies of
drinking water. Medical science recognized
hepatitis E as a separate disease in nineteen eighty.
E is also found in animal waste.
Studies have shown that the virus can infect many kinds of animals.
The W.H.O. says many hepatitis E cases
have been reported in Central and Southeast Asia, North and West Africa and
Mexico. No vaccines or medicines are
effective against hepatitis E. Most
people recover, usually in several weeks or months. But the disease can cause liver damage. And, in some cases, hepatitis E can be deadly.
The virus is especially dangerous to
pregnant women. Twenty percent of such
women living with hepatitis E die in the last three months of pregnancy.
discovered yet another kind of hepatitis in the nineteen nineties. It has been named hepatitis G. The hepatitis G virus is totally different
from any of the other hepatitis viruses.
Poretz is an infectious disease specialist in Washington, D.C. He says the hepatitis G virus is spread
through blood and blood products. But
he says the virus has not been found to cause any real disease.
World Hepatitis Alliance works to increase knowledge about the dangers of
hepatitis. The group says people should
know that the disease kills about one million five hundred thousand people each
year. It also says one in twelve people
worldwide are living with hepatitis B or hepatitis C. And, it says, most of those infected do not even know it.
cannot be cured. The only way to
protect against infection is to receive vaccines against hepatitis A and B, and
to avoid contact with the other viruses.
And that may be difficult.
that some kinds of hepatitis spread through sex or sharing needles. Blood products should be carefully tested
for hepatitis. People in high-risk
groups and those who have had hepatitis should not give blood. They also should not agree to provide their
organs to others after they die.
Donated organs can also spread hepatitis.
experts say people can take other steps to protect themselves. These include always washing your hands with
soap and water after using the restroom.
Also, wash your hands after changing a baby's diaper and before
preparing or eating food.
Experts say travelers should not drink
water of unknown quality when visiting foreign or unknown areas. Visitors to such areas also should avoid
eating uncooked fruits and vegetables.
And, again, do not forget to wash your hands!
SCIENCE IN THE NEWS was written by Nancy Steinbach. Our producer was Brianna Blake.
I'm Steve Ember.
Shirley Griffith. Internet users can
read our reports at voaspecialenglish.com.
Listen again next week for more news about science in Special English on
the Voice of America.