Genital Herpes -
Herpes simplex virus
Genital Herpes is caused by herpes
simplex virus type l or herpes
simplex virus type ll. Both viruses can infect the mouth (producing cold
sores) or the genital area (genital herpes).
Herpes Serology
A blood test for herpes is now available. Many
people hope this test will answer important questions they have about
herpes.
There are many uncertainties about the test and its
results are often difficult to interpret.
Consider the information in this pamphlet and discuss
with a doctor whether this test is likely to answer your questions.
Genital Herpes
Herpes simplex viruses (HSV) cause genital herpes. There
are two types of herpes simplex virus and they are referred to as type 1
and type 2. Both types can cause genital herpes. However, type 2 is the
usual cause of repeated attacks of genital herpes.
Type 1 HSV can also cause genital infections and tends
to produce fewer recurrences than that caused by type 2. Type 1 is the
most common cause of cold sores (oral herpes). About 80% of adults in
Australia have evidence of infection with type 1 HSV.
Diagnosis
T aking a swab test from a genital sore is the
only way to accurately diagnose genital herpes.
If people go to their doctor when a genital sore is not
present, a swab test cannot be used for diagnosis.
Blood tests
may help to make the diagnosis, but the results can
be difficult to interpret.
A blood test for herpes is a test for antibodies, which
are produced by the immune system when we are infected with HSV. A blood
test tells whether you have ever been infected with the herpes virus. It
cannot tell when you became infected.
A blood test does not detect the virus itself.
The herpes blood test cannot tell:
-
which part of your body is
infected (lips or genitals)
-
whether you will develop
symptoms of herpes
-
if your symptoms are due to
herpes.
It may take between six and eight weeks to detect
antibodies in a herpes blood test after first becoming infected with HSV.
Also, antibodies may disappear with time, especially if the person has
infrequent recurrences of herpes.
Herpes simplex type 1 and type 2 blood test results
Negative results for either type 1 or type 2 HSV mean
the person has not been infected with either virus in the past.
If a person has a positive result for type 1, they have
been infected with type 1 HSV in the past. This is a very common result.
Usually the infection is acquired in childhood and is located on the mouth
(cold sores). Nowadays, genital herpes infection with type 1 HSV is also a
possible explanation.
Positive results for type 2 means the person has been
infected with type 2 HSV in the past. A common explanation is that the
person has had genital herpes, caused by type 2. Another possibility is
that they have cold sores on the mouth caused by type 2 HSV. This is a
less common explanation.
False negative and false positive results
All tests may sometimes give an
incorrect result.
The current test used by our
laboratory service gives a positive result in about 5% of people who do
not have HSV infection (this is called a false positive result).
The test will give a negative
result in 15% of people who really are infected with HSV (this is a
false negative result).
The herpes blood test varies in
its reliability, so the meaning of a test result must be considered
along with your medical history.
Remember:
A positive blood test simply
indicates that the person has been infected with type 1 or type 2 HSV
(or both) some time in the past.
A positive blood test does not
indicate the site of the infection.
Serology tests do not provide
any information about whether symptoms (genital or oral) are due to
herpes.
A positive blood test does not
tell if the person is infectious at the time of the test.
More Information
STD Services web site: stdservices.on.net/std/herpes |
Pamphlet
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