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HEPATITIS B VIRUS
The risk of infection is directly correlated with the degree of contact
with blood in the workplace and the status of the source person. The highest
risk for infection is found in people exposed via a break in their skin to
contaminated blood of a person who is positive for both Hepatitis B surface
Antigen (HBsAG) and Hepatitis B e Antigen (HBeAG) - portions of the virus
that are responsible for the disease. The HBV virus can be found in several
body fluids, such as breast milk, bile, feces, saliva, semen and sweat.
However, the highest HBV titers of all body fluids, and the most important,
are found in blood.
Post Exposure Prophylaxis (PEP):
Antibodies are one part of a human's immunity. In general, humans who are
exposed to foreign organisms (e.g., bacteria, viruses) will produce
antibodies in order to fight those organisms and destroy them. Once
antibodies are produced, the immune system can produce even more antibodies
upon further exposure. In a sense, the immune system has a 'memory' of the
foreign organism.
The idea of vaccination relies on the capacity of the immune system's
"memory" of a foreign organism. A small dose of an organism, small enough so
that actual disease is not achieved, will produce an immune response and the
development of antibodies. After the organism is destroyed, the body will
stop making antibodies to fight it, but it will still have a "memory" of
that organism. Upon further exposure, even if at high doses, which could
produce disease, the immune system will be able to produce enough antibodies
to control the organism, destroy it, and thereby avoid disease.
Naturally, there are cases in which people never had a vaccination or an
exposure to a specific organism. They are thus at a higher risk of
developing disease, because their immune system may not be able to produce
enough antibodies to fight the organism. However, there is a medical
treatment in such situations. Medical centers have stores of collected,
preformed antibodies that they can give patients who don't have antibodies
themselves. These antibodies are also called immunoglobulins.
When the administration of Hepatitis B Immunoglobulin is indicated, it
should be administered as soon as possible after exposure, ideally within 24
hours. In the occupational setting, multiple doses of Hepatitis B
Immunoglobulin (antibodies to Hepatitis B) initiated within one week
following percutaneous (through the skin) exposure to HBsAG-positive blood
provides an estimated 75% protection from HBV infection. The Hepatitis B
Vaccine should also be administered as soon as possible, and may be given at
the same time as the immunoglobulins, but at a different site.
Vaccination against HBV
Over 100 million people in the US have been vaccinated as of 2000. In
fact, OSHA stipulates that vaccinations must be offered to workers with risk
for exposure. It is heartening to know that around 95% of all fire fighters
are in fact vaccinated against HBV.
The Hepatitis B Vaccine is administered as a series of three injections,
separated in time, into the deltoid muscle. 1 - 2 months after completing
the series, a person may be tested for response by checking for anti-HBV
antibodies. Non-responders to vaccination should be counseled about
re-vaccination (they have a 30 - 50 % chance of responding to a second
3-dose series) and about any precautions they should take.
Any blood or body fluid exposure sustained by an unvaccinated,
susceptible (non-immunized) person should lead to the initiation of the
hepatitis B vaccine series.
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(The above reflects information from: Updated U.S. Public Health
Service Guidelines for the Management of Occupational Exposures to HBV, HCV,
and HIV and Recommendations for Postexposure Prophylaxis Vol 50, No RR11;1
06/29/2001)
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