HEPATITIS B
HERITABILITY
few and mild to severe with pain, fever,
and
jaundice
.
Blood tests, including
liver
function tests
,
may be used for diagnosis.
In most cases of acute viral hepatitis,
natural recovery occurs within a few
weeks. If the disorder is caused by expo-
sure to a chemical or drug, detoxification
using an
antidote
may be possible.
In-
tensive care
may be required if the liver
is badly damaged. Rarely, a
liver trans-
plant
is the only way of saving life. In all
cases, alcohol should be avoided.
hepatitis B
Formerly known as serum
hepatitis
, this disorder is due to the hep-
atitis B virus, which is transmitted in
infected blood, blood products, or other
body fluids, often through contact with
needles, blood transfusions, or sexual
contact. After an incubation period of 1-6
months, the onset of symptoms, such as
headache, fever, and
jaundice
, is sudden.
Most patients recover, but hepatitis B
can be fatal. A vaccine is available.
In about 5 percent of cases, the virus
continues to cause inflammation and can
still be detected in the blood
6
months
after infection. People who suffer from
persistent infection are at long-term risk
of
liver cancer
and
cirrhosis
and may be
treated with
interferon
.
hepatitis C
Caused by the hepatitis C
virus and formerly known as non-A non-B
hepatitis
, this infection is often trans-
mitted through sharing needles. Blood
transfusions no longer pose a signifi-
cant risk because of blood screening.
Hepatitis C has an incubation period
of
6 -12
months and begins as a mild
illness which may go undetected. In
about 3 in 4 patients, chronic hepatitis
develops (see
hepatitis, chronic
),
which
can progress to
cirrhosis
of the liver and
an increased risk of
hepatoma
.
hepatitis, chronic
Inflammation of the
liver
persisting for a prolonged period.
Eventually, scar tissue forms and liver
cirrhosis
may develop.
Chronic hepatitis may develop follow-
ing an attack of acute hepatitis (see
hepatitis, acute
). It may also occur as the
result of an
autoimmune disorder
, a viral
infection (see
hepatitis, viral
), a reaction
to certain types of drugs or, more rarely,
to a
metabolic disorder
, such as
haemo-
chromatosis
or
Wilson's disease.
Chronic hepatitis
may
cause
slight
tiredness or no symptoms at all. It is
diagnosed by
liver biopsy
. Autoimmune
hepatitis is treated with
corticosteroid
drugs
and
immunosuppressants.
Viral
infections often respond to
interferon.
In the drug-induced type, withdrawal of
the medication can lead to recovery. For
metabolic disturbances, treatment de-
pends on the underlying disorder.
hepatitis D
An infection of the liver
caused by the hepatitis D virus, which
occurs only in people who already have
hepatitis B
infection. People who develop
hepatitis D will usually suffer from
severe chronic liver disease.
hepatitis E
A type of
hepatitis
, caused
by the hepatitis E virus, transmitted in
contaminated food or drink. The dis-
ease is similar to
hepatitis A
.
hepatitis, viral
Any type of
hepatitis
caused by a viral infection. Five viruses
that attack the liver as their primary tar-
get have been identified. They cause
hepatitis A
,
hepatitis B
,
hepatitis C
,
hep-
atitis D
, and
hepatitis E
.
hepatoma
A type of
liver cancer
.
hepatomegaly
Enlargement of the
liver
,
occurring as a result of any liver disor-
der (see
liver, disorders of
).
herbal medicine
Systems of medical
treatment in which various parts of
different plants are used to promote
health and to treat symptoms.
hereditary spherocytosis
See
sphe-
rocytosis, hereditary.
heredity
The transmission of traits and
disorders through genetic mechanisms.
Each individual inherits a combination of
genes
via the sperm and egg cells from
which he or she is derived. The interac-
tion of the genes determines inherited
characteristics, including, in some cases,
disorders or susceptibility to disorders.
(See also
genetic disorders; inheritance.)
heritability
A measure of the extent to
which a disease or disorder is the result
of inherited factors, as opposed to envi-
ronmental influences such as diet and
climate. Certain disorders (such as
hae-
mophilia
or
cystic fibrosis
) are known to
be caused entirely by hereditary factors.
Others are caused by environmental
factors. Between these extremes are
many disorders (such as
schizophrenia
)
H
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