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Causes
Your liver is located on the right side of your abdomen, just
beneath your lower ribs. It performs more than 500 functions,
including processing most of the nutrients absorbed from your
intestines, removing drugs, alcohol and other harmful
substances from your bloodstream, and manufacturing bile — the
greenish fluid stored in your gallbladder that helps digest
fats. Your liver also produces cholesterol, blood-clotting
factors and certain other proteins.
Because of the complexity of the liver and its exposure to so
many potentially toxic substances, it would seem especially
vulnerable to disease. But the liver has an amazing capacity
for regeneration — it can heal itself by replacing or
repairing injured tissue. In addition, healthy cells take over
the function of damaged cells, either indefinitely or until
the damage has been repaired. Yet in spite of this, your liver
is prone to a number of diseases that can cause serious or
irreversible damage, including hepatitis B.
Acute vs. chronic hepatitis B
Hepatitis B infection may be either acute — lasting less than
six months — or chronic, lasting six months or longer. If the
disease is acute, your immune system is able to clear the
virus from your body, and you should recover completely within
a few months. When your immune system can't fight off the
virus, HBV infection may become lifelong, leading to serious
illnesses such as cirrhosis and liver cancer.
Most people who acquire hepatitis B as adults have an acute
infection. But the outlook isn't nearly as hopeful for infants
and children. Most infants infected with HBV at birth and many
children infected between 1 and 5 years of age become
chronically infected. Chronic infection may go undetected for
decades until a person becomes seriously ill from liver
disease.
Hepatitis B is one of six currently identified strains of
viral hepatitis — the others are A, C, D, E and G. Each strain
is unique, differing from the others in severity and in the
way it spreads.
Major ways transmission occurs
In industrialized countries, you're most likely to become
infected with HBV in the following ways:
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Sexual transmission.
You may become infected if you have unprotected vaginal, anal
or oral sex with an infected partner whose blood, saliva,
semen or vaginal secretions enter your body. You can also
become infected from shared sexual devices if they're not
washed or covered with a condom. The virus is present in the
secretions of someone who's infected and enters your body
through small tears that can develop in your rectum or vagina
during sexual activity.
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Transmission through needle sharing.
HBV is easily transmitted through needles and syringes
contaminated with infected blood. That's why sharing IV drug
paraphernalia puts you at high risk of hepatitis B. Your risk
increases if you inject drugs frequently or also engage in
high-risk sexual behavior. Although avoiding the use of
injected drugs is the most reliable way to prevent infection,
you may not choose to do this. If so, one way to reduce your
risk is to participate in a needle exchange program in your
community. These programs allow you to exchange used needles
and syringes for sterile equipment. In addition, consider
seeking counseling or treatment for your drug use.
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Transmission through accidental needle sticks.
Hepatitis B is a concern for health care workers and anyone
else who comes in contact with human blood. If you fall into
one of these categories, get vaccinated against hepatitis B in
addition to following routine precautions when handling
needles and other sharp instruments.
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Transmission from mother to child.
Pregnant women infected with HBV can pass the virus to their
babies. If you have hepatitis B, having your baby receive a
shot of hepatitis B immune globulin at birth, along with the
first in a series of three hepatitis B vaccines, will greatly
reduce your baby's risk of getting the virus.
For you to become infected with HBV, infected blood, semen,
vaginal secretions or saliva must enter your body. You can't
become infected through casual contact — hugging, dancing or
shaking hands — with someone who has hepatitis B. You also
can't be infected in any of the following ways:
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Coming into contact with the sweat or tears of someone with
HBV
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Sharing a swimming pool, telephone or toilet seat with someone
who has the virus
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Donating blood
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