Herpes tests are done to find the herpes simplex
virus (HSV). An HSV infection can cause small, painful sores that look like
blisters on the skin or the tissue lining (mucous membranes) of the throat, nose, mouth,
urethra, rectum, and
vagina. A herpes infection may cause only a single
outbreak of sores, but in many cases the person will have more
There are two types of HSV.
- HSV type 1 causes cold sores (also
called fever blisters) on the lips. HSV-1 is generally spread by kissing or by
sharing eating utensils (such as spoons or forks) when sores are present. HSV-1
can also cause sores around the genitals.
- HSV type 2 causes sores
in the genital area (genital herpes), such as on or around the vagina or penis.
HSV-2 also causes the herpes infection seen in babies who are delivered
vaginally in women who have genital herpes. HSV-2 is generally spread by sexual
contact. HSV-2 can sometimes cause mouth sores.
In rare cases, HSV can infect other parts of the body, such
as the eyes and the brain.
Tests for HSV are most often done only
for sores in the genital area. The test may also be done using other
types of samples, such as spinal fluid, blood, urine, or tears. To see whether
sores are caused by HSV, different types of tests may be done.
- Herpes viral culture.
Cells or fluid from a fresh sore are collected with a cotton swab and placed in
culture cup. The culture often fails to find the
virus even when it is present (false-negative results).
- Herpes virus antigen detection test. Cells from a fresh sore are scraped off and then smeared onto a
microscope slide. This test finds markers (called
antigens) on the surface of cells infected with the
herpes virus. This test may be done with or in place of a viral
- Polymerase chain reaction (PCR) test. A PCR test can be done on cells or fluid from a sore or on blood
or on other fluid, such as spinal fluid. PCR finds the genetic material (DNA) of the HSV virus. This test can tell the
difference between HSV-1 and HSV-2. Using the PCR test on skin sores isn't common. PCR is used mainly for testing spinal fluid in rare cases when herpes may have caused an infection in or around the brain.
- Antibody tests. Blood tests can find
antibodies that are made by the
immune system to fight a herpes infection. Antibody
tests are sometimes done but are not as accurate as a viral culture at finding
the cause of a specific sore or ulcer. Antibody tests cannot always tell the
difference between a current active herpes infection and a herpes infection
that occurred in the past. Because antibodies take time to develop after the
first infection, you may not have a positive antibody test if you have just
recently been infected. Some blood tests can tell the difference between HSV-1