Herpes Tests – Its Types, Risks Involved and Treatment

Test Overview
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 outbreaks.

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. In rare cases, the test may 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 a culture cup. A viral culture is the best method of identifying a genital herpes infection. But 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 culture.
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. The PCR test is not often done on skin sores, but it is best for testing spinal fluid, for those rare cases in which herpes may cause 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 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 and HSV‐2

A herpes infection cannot be cured. After you become infected with HSV, the virus stays in the body for life. It “hides” in a certain type of nerve cell and causes more outbreaks of sores in some people. Recurring infections can be triggered by stress, fatigue, sunlight, or another infection, such as a cold or flu. Medicine can relieve symptoms and shorten the length of the outbreaks, but medicine cannot cure the infection.

Why It Is Done
A test for herpes may be done to:

Find out which virus type (HSV‐1 or HSV‐2) is causing sores around the mouth or in the genital area.
Find out whether the sex partner of a person with genital herpes may be infected with HSV.
Diagnose a herpes infection in a newborn baby whose mother has genital herpes.

How To Prepare
If you may have genital herpes, do not have sexual contact until your test results are back. You can lower the chance of spreading the disease to your partner(s).

If a sample from the urethra will be collected, do not urinate for 2 hours before the test.

For women, if a cervical sample will be collected, do not douche for 24 hours before the test.

How It Is Done
For a viral culture, viral antigen test, or PCR test, a clean cotton swab is rubbed against a herpes sore to collect fluid and cells for examination. Samples may be collected from the vagina, cervix, penis, urethra, eye, throat, or skin. Doctors usually collect a sample from small sores that are only a few days old. Viruses are more likely to be found in small newly formed sores.

For an antibody test, the health professional drawing blood will:

Wrap an elastic band(tourniquet) around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. More than one needle stick may be needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is collected.
Put a gauze pad or cotton ball over the needle site as the needle is removed.
Put pressure to the site and then a bandage.

During The Test
You are likely to feel some mild discomfort or pain when the sores are scraped to collect a sample for testing. The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks
If an antibody test is done, there is very little chance of problems from having a blood sample taken from a vein.

You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
Ongoing bleeding can be a problem for people with bleeding disorders. If you have any such problems, or if you take blood‐thinning medicine, tell your doctor before your blood sample is taken.

Results
Herpes tests are done to find the herpes simplex virus (HSV). Results for a rapid viral culture may take 2 to 3 days, while results for a standard culture can take up to 14 days. Antigen detection test results are ready in a day. Polymerase chain reaction PCR test results are ready in 1 to 3 days. Results from an antibody blood test are ready in 2 days. The results from an antibody test called an enzyme‐linked immunosorbent assay (ELISA, EIA) may be ready in about 2 hours.

Herpes tests
Normal:

Normal results are called negative.
No HSV grows in the viral culture.
No viral antigens or DNA are found.
No herpes antibodies are present in the blood.

Abnormal:

Abnormal results that show HSV are called positive.
HSV grows in the viral culture.
HSV antigens or DNA are found.
Antibodies to the herpes virus are present in the blood.

Samples taken from newly formed sores containing fluid (blisters) are generally better than samples collected from older, crusted sores.

A normal (negative) test result does not mean you do not have a herpes infection. If the first test is negative but you have symptoms of Herpes Tests, more tests may be done.

What Affects the Test?
Reasons you may not be able to have the test or why the results may not be helpful include:

If a culture sample is taken from a crusted, older sore.
If a blood sample is taken before antibodies against HSV have formed. This period is called the window period or seroconversion period.
If you are taking antiviral medicines, such as acyclovir, famciclovir, ganciclovir, or valacyclovir