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What is Herpes Simplex Virus test?

Herpes simplex virus or HSV is the causative agent of herpes. There are two different types of HSV- HSV1 that causes oral sores and HSV2 that chiefly affects genital organs. The virus enters the body through injured skin, mucus secretion in the mouth and sexual contact.

In the first stage of the infection (primary stage), patients present with fever, soreness in the throat and mouth or painful boil or eruptions in the genital organs. In the second stage, the infection becomes inactive and the virus continues to survive throughout the life in the spinal cord. However, a latent infection can reactivate any time during periods of stress, due to an injury, immunosuppressive diseases such as cancer and AIDS, exposure to sunlight, or during monthly periods in women.

HSV is transmitted from an infected mother to the baby during delivery or before birth leading to congenital herpes and birth defects in the baby’s brain and central nervous system. 

Various tests are used for the detection of HSV in the body. These include blood tests, viral culture test and antibody test. A polymerase chain reaction or PCR is sometimes suggested to differentiate HSV eruptions from other types of vascular eruptions and to differentiate between HSV1 and HSV2 infections.

  1. Why is Herpes Simplex Virus test performed?
  2. How do you prepare for a Herpes Simplex Virus test?
  3. How is the Herpes Simplex Virus test performed?
  4. What do Herpes Simplex Virus test results mean?

The HSV test is performed when an HSV infection is suspected due to the following symptoms:

  • Multiple small bubble-like boils or fluid-filled eruptions or small ulcers around the mouth, lips (cold sore) and fingers (whitlow). HSV has a tendency to spread easily from one infected person to another
  • Multiple small boils in the genital area, urethra, vagina, buttocks, etc.
  • Pain or burning sensation in the genital organs in both men and women
  • Thick white or yellow discharge from vagina or urethra
  • Sensation of burning while urination

Other complications include the following:

No special preparations are needed before this test. Your doctor would tell you the reason for the test and he/she will also explain the whole procedure to you. Ask your doctor if you need to follow any specific instructions for the test.

HSV can be detected by either checking for the presence of the virus or antibodies against the virus in the body. Your doctor may suggest one or more of the below-mentioned tests:

  • Blood test: 7 mL of blood sample will be collected from your arm to be sent to a lab. for analysis
  • Culture test: Sample collected from the eruptions or the blood sample is used and mixed with an artificial matter that favours the growth of the virus outside the body
  • Polymerase chain reaction (PCR): The genetic material of HSV is detected in the blood or fluid sample using PCR. The test is commonly used in the diagnosis of HSV2 infection
  • Antibody testing: Antibodies (IgG and IgM) that are produced by the body’s immune system in response to HSV antigens are detected by the process of enzyme-linked immunosorbent assay and indirect immunofluorescent assay
    • IgM antibodies are secreted within some days of primary or first infection
    • IgG antibodies increase in the blood 1 to 2 weeks after the primary infection and attain peak values at 6 to 8 weeks after the infection. The levels start decreasing after 8 weeks and remain stable throughout life

Normal results:

Negative results for IgG and IgM antibodies indicate normal results and absence of HSV1 and HSV2 infection in the body. No viral growth in culture test and absence of HSV DNA in PCR would also indicate absence of HSV in the body.

Abnormal results:

Positive results indicate the following:

  • Positive results for IgM antibodies in the blood indicate the presence of HSV1 or HSV2 infection in the body
    • Positive IgM antibodies indicate that the person was recently infected and the infection is in the active phase
    • Positive IgG antibodies indicate that the infection occurred in the past.
    • Increased levels of IgG antibodies in patients with previous active infection signify the re-appearance of active infection
  • Positive culture and PCR test indicate HSV infection in the body. Culture and direct immunofluorescence test are used to identify HSV1 and HSV2 infection. A PCR test is much more sensitive for viral detection than a culture. Also, it uses a small amount of sample and provides quick results - as opposed to the few days taken by a viral culture test.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

References

  1. World Health Organization [Internet]. Geneva: World Health Organization; Herpes simplex virus
  2. NHS Inform. Cold sore. National health information service, Scotland [internet].
  3. Stanley Davidson. Davidsons Principles And Practice Of Medicine. 21st Edition, Elsevier
  4. Denise. D. Wilson. McGraw-Hill Manual of Laboratory and Diagnostic Tests. 1st Edition; ISBN10: 0071481524
  5. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Genital HSV Infections
  6. American Cancer Society [internet]. Atlanta (GA), USA; Viruses that can lead to cancer
  7. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Genital Herpes - CDC Fact Sheet (Detailed)
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