Hepatitis B is caused by a virus, which can cause both acute and chronic
hepatitis. Chronic hepatitis develops in the 15 per cent of patients
who are unable to eliminate the virus after an initial infection.
Identified methods of transmission include blood (blood transfusion, now
rare), tattoos (both amateur and professionally done), sexually
(through sexual intercourse or through contact with blood or bodily
fluids), or via mother to child by breast feeding (minimal evidence of
transplacental crossing). However, in about half of cases the source of
infection cannot be determined. Blood contact can occur by sharing
syringes in intravenous drug use, shaving accessories such as razor
blades, or touching wounds on infected persons. Needle-exchange
programmes have been created in many countries as a form of prevention.
Patients with chronic hepatitis B have antibodies against hepatitis B,
but these antibodies are not enough to clear the infection that
establishes itself in the DNA of the affected liver cells. The continued
production of virus combined with antibodies is a likely cause of
immune complex disease seen in these patients. A vaccine is available
that will prevent infection from hepatitis li for life. Hepatitis B
infections result in 500,000 to 1,200,000 deaths per year worldwide due
to the complications of chronic hepatitis, cirrhosis, and
patoceilular carcinoma. Hepatitis B is endemic in a number of {mainly
South-East Asian) countries, making cirrhosis and hcpatocellular
carcinoma big killers. There are six FDA approved treatment options
available for persons with a cironic hepatitis B infection:
alpha-interferon, pegylated nilcrferon adefovir, entecavir, telbivudine
and lamivudine. About 45 per cent of persons on treatment achieved
response.
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