Laboratory
Tests
Why Test?
It is difficult for your healthcare provider to make a diagnosis
of genital herpes by physical examination alone. For this reason,
laboratory tests are a critical component of an accurate diagnosis
and will help you and your healthcare provider determine what actions
need to be taken to manage your symptoms and help you prevent transmission
to a sexual partner or unborn child.
Laboratory testing
is required for an accurate diagnosis.
There are several types of laboratory tests that a healthcare
provider may use to make a diagnosis. The following information
will help you take an active role in your diagnosis and treatment.
If you have genital lesions or sores at the time of your physical
exam, a swab of the lesion should be taken and sent to the laboratory
for viral culture.
If your lesions are healing, your symptoms are unclear, or you
are sexually active but do not have symptoms, a blood test should
be performed to confirm infection.
Your healthcare provider should order a type-specific herpes simplex
virus (HSV) serology test to determine if the infection is HSV
type-1 or HSV type–2. This information is important for
treatment decisions.
The HSV type-specific serology test must be based upon glycoprotein-G
based technology to be accurate.
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Types of Laboratory Tests
The diagnostic options for HSV are Virus Detection tests or Antibody
Detection tests.
Virus Detection tests are performed on a viral sample vigorously
swabbed from an active lesion. The isolation of herpes simplex
virus in cell culture is the most common test requested by healthcare
providers. To be accurate, herpes culture requires live virus samples
obtained from lesions and special care during transport to the
lab. When good quality samples are used, culture can be reliable
in determining if you have HSV and can also indicate whether you
have HSV type-1 or HSV type-2. But you must have active lesions
at the time of testing in order for this test to be reliable. Although
a positive culture result is generally reliable, 50% to 70% of
cultures are falsely negative in recurrent episodes. Type-specific
serology tests should be used to confirm a clinical diagnosis when
symptoms are absent or not obvious.
Antibody Detection tests (serology tests) involve the detection
of antibodies to HSV in the blood. Both type-specific HSV antibodies
(specific to HSV type-1 or HSV type-2 virus) and nonspecific or
type-common antibodies develop during the first several weeks following
infection and remain in the blood indefinitely. Older serology
tests measure type-common antibodies and cannot differentiate between
HSV type-1 and HSV type–2. These tests are not useful in
making a definitive diagnosis of genital herpes in a patient with
a prior oral HSV type-1 infection. For this reason, the CDC recommends
that type-specific serology tests, based upon glycoprotein G (gG)
technology, be used to diagnose genital herpes.
There are several type-specific tests on the market but currently
only two manufacturers offer FDA-cleared methods based upon glycoprotein
G technology needed for an accurate diagnosis. They are the HerpeSelect
HSV type-1 and HSV type-2 tests from Focus Diagnostics, which
have been in use for several years, and recently released tests
from Trinity Biotech. A third test not currently marketed in the
US, the POCkit® HSV type-2
assay, does not test for HSV type-1.
Ask your healthcare provider to confirm that the serology test
ordered for you meets the following criteria:
- Type-specific for HSV type-1 and HSV type-2
- Based on Glycoprotein G technology (this will be stated in
the kit insert)
- FDA-cleared
> Click here for more information on HerpeSelect type-specific serology tests
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