Human immunodeficiency virus (HIV) is an infectious disease that
attacks the immune system. If it is not treated, it can develop into acquired immunodeficiency syndrome (AIDS),
which is a prolonged and fatal illness. HIV is spread through vaginal, oral, or
anal sexual contact. It is also spread through blood, blood factor products,
injection drug use, and breast milk.
What Is the ELISA/Western
A series of
blood screenings are performed to test for HIV. The enzyme-linked immunosorbent assay (ELISA),
also known as an enzyme immunoassay (EIA), is the first test that your
healthcare provider will order to screen for HIV. ELISA, like the Western blot
test, detects HIV antibodies in your blood. Antibodies are proteins your immune system produces in
response to the presence of foreign substances, such as viruses. If you test
positive for HIV on the ELISA test, your provider will order the Western blot test to confirm HIV
When Is this Test
and Western blot tests are recommended if you have been exposed to HIV or are
at risk for contracting HIV. Those at risk for HIV include:
(IV) drug users
who have unprotected sex, especially with someone who has HIV or has an unknown
who have had sexually transmitted diseases (STDs)
who had blood transfusions or blood clotting factor injections before 1985
You may opt to
have the test done if you are uncertain about your HIV status, even if you are
not in a high-risk group. It is a good idea to be tested on a regular basis if
you participate in high-risk behaviors, such as IV drug use or unprotected sex.
How Do I Prepare for the
You do not
need to do anything to prepare for the ELISA or Western blot test. It takes
very little time to give a blood sample, but it may take several days or weeks
to get the results. Make sure to tell your healthcare provider as well as the
laboratory technician if you have a fear of needles or faint at the sight of
blood so that they can take appropriate precautions to provide for your safety
in the event that you should faint.
What Happens During the
having these tests, you will probably need to sign a consent form. The test and
procedure should be explained to you. The procedure for getting a sample of
your blood is the same for both tests. A medical professional will:
your inner arm with a solution to decrease the number of bacteria or germs on
the skin surface overlying the vein that they intend to access for the blood
a tourniquet, or elastic band, around your arm to make the veins swell with
a needle into one of your veins and draw a small sample of blood into a tube
the needle and apply a bandage
You may be asked
to elevate or flex your arm to reduce the blood flow after the test, to
decrease further bleeding.
blood sample is not painful, though you may feel a sting or a pricking
sensation as the needle goes into your vein. Your arm may throb slightly after
sample will be sent to a laboratory for analysis. For the ELISA test, a lab
technician adds the sample to a petri dish containing HIV antigen. An antigen is any foreign substance,
such as a virus, that causes your immune system to respond.
blood contains antibodies to HIV, it will bind with the antigen. The technician
will check this by adding an enzyme (a protein that helps speed up chemical
reactions) to the petri dish and watching how your blood and the antigen react.
If the contents of the dish change color, you may have HIV.
process of a Western blot test is similar. However, the Western blot method is
more complicated. It involves separating the HIV sample into its component
proteins using an electrical current. Then, these proteins are transferred to a
special kind of paper (blotting) and reacted with your blood sample. An enzyme
is used to cause color change and detect antibodies.
Are There Any Risks?
are very safe, but rare complications can occur. For example, you may:
lightheaded or faint, especially if you have a fear of needles or blood
an infection at the site of the needle insertion
a bruise at the puncture site
trouble stopping the bleeding
Make sure to
tell your healthcare provider if you’ve had trouble giving blood in the past,
bruise easily, or suffer from a bleeding disorder, such as hemophilia or are
taking anticoagulant medications (also referred to as “blood thinners”).
Contact your healthcare provider right away if you experience any of these
What Do the Test Results
If you test
positive for HIV on the ELISA test, you might have HIV. However, sometimes
there can be false positives with
the ELISA screen. This means that test results indicate that you have HIV when
you actually do not. Further testing is required to confirm whether you have
the disease. For example, having certain disease such as Lyme disease,
syphilis, or lupus may produce a false positive for HIV in an ELISA test.
If you test
positive on the ELISA screen, your healthcare provider will order a Western
blot test. If you test positive for HIV with the Western blot test, you
probably have HIV.
HIV does not show up on the ELISA test even though you are infected. This can
happen if someone is in the early stages of the infection, and his or her body
has not produced enough antibodies (in response to the virus) for the tests to
detect. This early stage of the disease, in which a person has HIV but tests
negative for it, is known as the “window period.”
the Centers for Disease Control and Prevention (CDC), a person’s window period
is usually between two and eight weeks, and the average is 25 days. However, in
rare cases, some people can take as long as six months to develop antibodies.
After the Test
tests are simple and straightforward, waiting for the results can create
anxiety. In many cases, you will have to talk to someone either in person or
over the phone to receive your results, regardless of whether they are positive
or negative. A positive test result can be emotionally devastating. Your healthcare
provider can refer you to counseling or HIV support groups.
is very serious, there is medication that can help prevent the disease from
developing into AIDS, so that you can live a full and long life. The earlier
you discover your HIV status, the earlier you can begin treatment to prevent
health complications or transmission of the infection to others.