Hepatitis B
Hepatitis is
a general term which means inflammation of the liver. This
inflammation of the liver can have different causes: infection, a
disorder of the immune system, or exposure to alcohol, certain
medications, toxins, or poisons.
Hepatitis B is caused by an infection
with the Hepatitis B virus (HBV), a member of the
Hepadnavirus family and one of several unrelated viral species which
cause viral hepatitis.
This
infection has 2 phases: acute and chronic. The acute (new,
short-term) phase occurs shortly after exposure to the virus. A
small number of people develop a very severe, life-threatening form
of acute hepatitis called fulminant hepatitis. The chronic (ongoing,
long-term) hepatitis B is an infection with HBV that lasts longer
than 6 months. Once the infection becomes chronic, it may never go
away completely.
Hepatitis B is largely transmitted
through exposure to bodily fluids(semen, saliva) containing the
virus: unprotected sexual contact, blood transfusions, re-use of
contaminated needles and syringes, vertical transmission from mother
to child during childbirth, and so on. Hepatitis B is NOT
transmitted through hugging, handshaking, breastfeeding, eating food
or drinking water,
casual
contact (such as an office or social setting), and neither by
sneezing or coughing.
In the United States approximately
200,000-300,000 persons become infected with HBV.
More than 10,000
require hospitalization, and 250 die of fulminant disease. In
addition, 22,000 HBV-infected women give birth each year. The
prevalence of chronic HBV infection in the United States is 0.35%.
Approximately 5% of the world's
population has chronic HBV infection; it is the leading cause of
chronic hepatitis, cirrhosis, and hepatocellular carcinoma
worldwide. An estimated 500,000-1,000,000 persons die annually from
HBV-related liver disease. Countries are classified as follows: with
low endemic rates (<2% of the general population has the antibody to
the hepatitis B surface antigen [HBsAg]), intermediate endemic rates
(2-8% positive for HBsAg), or high endemic rates (>8% positive for
HBsAg).
In the
United States, hepatitis B is largely a disease of
young adults aged 20-50 years. The rate of progression of HPV from
acute infection to chronic infection is determined by the age when
the primary infection occurs: 90% during the perinatal period,
20-50% in children aged 1-5 years, and less than 5% in adults.
SIGNS AND
SYMPTOMS
Hepatitis B
has an incubation period that ranges from 6 weeks to 6 months and
the manifestations of the disease depend on the age at infection,
the infected person’s immune system, the level of HBV replication.
Perinatally infected infants generally have no clinical signs or
symptoms, and infection produces typical illness in only 5-15% of
children aged 1-5 years.
Older children and adults are symptomatic in 33-50% of infections.
The symptoms of acute HPB
infection include: anorexia, nausea, malaise, vomiting, arthralgias,
myalgias, headache, photophobia, pharyngitis, cough, coryza,
jaundice, dark urine (like cola or tea), clay-colored or light
stools, and abdominal pain, jaundice, itching all over the body.
Most people think they have flu and never
think about having HBV infection.
A few patients may have more severe
liver disease (fulminant hepatic failure), and may die as a result
of it. The infection may also be entirely asymptomatic and may go
unrecognized.
Chronic infection with hepatitis B
virus may be either asymptomatic or may be associated with a chronic
inflammation of the liver (chronic hepatitis), leading to cirrhosis
over a period of several years. This type of infection dramatically
increases the incidence of liver cancer. Hepatitis D infection
requires a concomitant infection with hepatitis B. Co-infection with
hepatitis D increases the risk of liver cirrhosis and subsequently,
liver cancer.
TREATMENT
There are several types of treatment
for Hepatitis B in the form of antivirals such as
Interferon alfa-2b (Intron A),
Lamivudine (Epivir-HBV), Adefovir dipivoxil (Hepsera), Entecavir (Baraclude).
Chronic carriers should be strongly
encouraged to avoid consuming alcohol as it increases their risk for
cirrhosis and hepatocellular carcinoma
(liver cancer).
Infants born to mothers known to
carry hepatitis B can be treated with antibodies to the hepatitis B
virus (hepatitis B immune globulin or HBIg). When given with the
vaccine within twelve hours of birth, the risk of acquiring
hepatitis B is reduced 95%. This treatment also allows a mother to
safely breastfeed her child.
COMPLICATIONS
A major complication of Hepatitis B
is fulminant hepatitis. The symptoms of fulminant hepatitis include
hepatic
encephalopathy that may evolve to deep coma, the liver is usually
small, and the prothrombin time (a test
that measures blood clotting ability) is excessively
prolonged.
Chronic hepatitis can lead to
cirrhosis and hepatocellular carcinoma.
Other complications include:
pancreatitis (inflammation of the
pancreas), myocarditis (inflammation
of heart muscle), atypical pneumonia (an
acute respiratory disease marked by high fever and coughing),
aplastic anemia (an anemia caused by
deficient red blood cell production by the bone marrow),
transverse myelitis (An acute attack of
inflammatory demyelination that involves both sides of the spinal
cord. The spinal cord loses its ability to transmit nerve impulses
up and down. Paralysis and numbness are experienced in the legs and
trunk below the level of the inflammation.), peripheral
neuropathy (a condition of the nervous
system that usually begins in the hands and/or feet with symptoms of
numbness, tingling, burning and/or weakness).
PREVENTION
Hepatitis B is one of the major diseases of mankind that can be
prevented with vaccination. Two types of recombinant hepatitis B
vaccines are licensed for use in the
United States; both are effective
and safe.
There is a universal vaccination
which refers to the administration of HBV vaccine to all infants as
a part of the routine childhood immunization schedule and to all
children younger than 11 or 12 years who have not previously
received a vaccine, and a passive immunization which refers to the
administration of preformed human or animal antibody, in the form of
hepatitis B immunoglobulin (HBIG), to patients after or just before
exposure.
Almost anyone can receive the
vaccine, including infants, older adults and those with compromised
immune systems. Infants often receive the vaccine in the first year
of life — typically at two, four and nine months of age.
Another means of preventing
getting infected with HBV is to avoid unprotected sexual contact
unless you are absolutely certain that your partner isn’t infected
with HBV, or any other STD. If you use a needle to inject illicit
drugs, make sure it’s sterile and don’t share it.
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