Diagnosis of HIV DISEASE--
What is ELISA test for HIV ?-- Whenever any organism enters the
body, the immune system produces antibodies to it. Hence
presence of these antibodies is an indirect evidence of the
infection. ELISA test for HIV is a test that detects the
antibodies to HIV. A positive ELISA test is therefore an
indirect evidence of HIV infection. However the body takes 6
weeks to 3 months to produce antibodies. Thus even after
infection the test becomes positive only after 6 weeks to 3
months. This period is called as the window period. During this
period the patient is infective but the test is negative. Should
a single ELISA test positive report be taken as an evidence of
HIV infection ?-- In case of ELISA positive; either the test is
repeated or a more specific test like Western Blot is done to
confirm the diagnosis.
What is Western Blot test? This is a more specific test for
diagnosis of HIV infection. It is generally used to confirm a
positive ELISA report.
What is PCR test for HIV ?-- PCR stands for Polymerase Chain
reaction. It is an advanced test that detects HIV even if it is
present in the blood in very small quantity. Hence it can detect
the presence of HIV much earlier as compared to ELISA, thus
decreasing the window period considerably. Similarly testing for
p24 antigen is also a test that can decrease the window period.
If a p24 test becomes negative after being positive earlier,
does it mean that the person has been cured of HIV infection ?--
NO. p24 is an antigen of HIV. Once HIV enters the body it is
found in the blood in high quantity. The test is thus found to
be positive at this time. After about 2 to six months the virus
goes into hiding in the lymph nodes. At this time the p24 is
likely to become negative. However this is the normal
progression of HIV infection & does not mean that the patient
has been cured of HIV infection
for further details log onto
http://doctoronline.s5.com/hiv4.html
About the author:
MBBS, MD
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