It is a common viral infection caused by herpes simplex virus (HSV). Its 2 types present include HSV-1 & HSV-2. Both viruses are known to be contagious (transmissible) and cause sores or blisters around the mouth or genitals with other symptoms too. The HSV-1 is known to cause oral herpes which will affect mouth & surrounding skin and can spread via contact with moist skin of infected mouth. While HSV-2 is known to cause genital herpes i.e. sores develop on penis, around or inside vagina, buttocks, or on anus. HSV-2 can be sexually transmitted. It may also be transmitted from a genital herpes mother to her baby while giving birth.
What is Herpes IgM Lab Test?
For the detection/diagnosis of HSV infection, an immunoglobulin M (IgM) blood test is performed. This test looks for antibodies (& not the virus) which are produced by the body in response to the infection. Specific HSV IgM antibodies will develop early (first antibody to develop) during an infection & helps detect primary (early) HSV infection. IgM antibodies are short-lasting & only detectable during an active or recent infection.
Why is Herpes IgM Lab Test done?
It is the earliest test done to detect herpes. The sole purpose of this test is to learn & confirm that person has herpes infection after an outbreak. However, it isn't used to detect herpes directly. Herpes IgM antibodies can take at least 10 days (to become positive) to develop after primary infection so it's better not to rush to the doctor for tests if you've not yet developed the symptoms.
A blood sample is drawn from vein in the upper arm
About 8 to 10 mL of blood is extracted into a vacuum-sealed test tube
The tube is then sent to the laboratory where enzyme-linked-immunosorbent assay (ELISA) technique is used to evaluate HSV IgM antibodies.
What are normal ranges of IgM?
Adult normal IgM antibody range is 0.4 to 2.5 g/L.
What are high IgM levels for herpes?
Positive & 1.10 IV or greater show that IgM antibody for herpes infection is detected which indicate recent or current infection
Do IgM blood tests show accuracy in detecting herpes?
No, IgM tests are unable to accurately distinguish between HSV-1 & HSV-2 antibodies and therefore very easily produce false positive results for HSV-2.
How long will it take for HSV IgM to stay positive?
It takes HSV IgM antibodies at least 7 to 10 days to come in detectable levels & stay high for about two weeks after initial infection.
What are chances of getting herpes if your partner doesn't have the infection?
The chances can be that your partner doesn't have visible sores, or he/she is unknown to the fact that they are infected. Or you may get genital herpes if you involve in oral sex with a partner having oral herpes.
HSV IgM antibodies can take at least 10 days to develop in detectable amounts so wait at least 2 weeks (if no symptoms) before getting tested. However, IgM antibody test for herpes has lessened & IgG test is more preferred due to a number of reasons.
INTERPRETATION OF THE RESULTS:
"Negative" IgM: simply indicates that no antibodies were found & is considered normal i.e. you've not contracted the infection.
"Positive" IgM: mostly the positive result is associated with having an early or new infection. However, people having recurrent herpes infection also tend to show positive IgM results.